Participant’s Handout

SVEL29B 10/01V 1.0

Aftersales Training

Petrol EngineManagementPart 2

Topic Page

Table of Contents

OBD Update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

On Board Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

OBD systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Telltale lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Trouble codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Cyclic test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Misfire detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

E - Gas throttle body system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Catalytic convertor with twin O2 sensors . . . . . . . . . . . . . . . . . . . . . . 24

Short term/long term fuel trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Management system overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Engine / engine-management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Ignition systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Exhaust gas re-circulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

4

OBD Update

Introduction

With the introduction of the MiniPeople Carrier Agila for MY 2000 ½,Opel was obliged to implement theOn Board Diagnosis system into theengine management system. Theapplication of the On BoardDiagnosis system is mandatory fornewly type-approved passengercars (with a petrol engine) up to aweight of 2500 kg’s as of 01-01-2000, and of newly sold cars as of01-01-2001.This means that for the Model Year2001 Opel must incorporate OBDinto all of its (petrol) enginemanagement systems.

All Powertrain Control Modules usedin these Opel vehicles are Flashprogrammable.

This chapter serves as an updateand review of the handout. As ofMY 2001 all newly sold Opelvehicles are equipped with enginemanagement systems that complywith the OBD regulations. whereengine management systems usedifferent strategies for instance forfuel injection and ignition, the OBD-strategies of the used enginemanagement systems are alsodifferent.

The following is an overview of Opel/Vauxhall vehicles equipped withOBD.

Model Year 2000 Agila Z 10 XE Motronic ME 1.5.5Agila Z 12 XE Motronic ME 1.5.5

Model Year 2001 Corsa-C Z 10 XE Motronic ME 1.5.5Corsa-C Z 12 XE Motronic ME 1.5.5Corsa-C Z 14 XE HSFI 2.1

Astra-G Z 12 XE Motronic ME 1.5.5Astra-G Z 14 XE HSFI 2.1Astra-G Z 16 SE HSFI 2.1Astra-G Z 16 XE HSFI 2.1Astra-G Z 18 XE Simtec MS 71Astra-G Z 20 LET Motronic ME 1.5.5Astra-G Z 22 SE GMPT E-15

Vectra-B Z 16 XE HSFI 2.1Vectra-B Z 18 XE Simtec MS 71Vectra-B Z 22 SE GMPT E 15Vectra-B Y 26 XE Motronic M 3.1.1

Zafira Z 16 XE HSFI 2.1Zafira Z 18 XE Simtec MS 71Zafira Z 22 SE GMPT E 15

Omega-B Z 22 XE Simtec MS 71Omega-B Y 26 XE Motronic M 3.1.1Omega-B Y 32 XE Motronic M 3.1.1Omega-B Y 57 XE PCM 32 UVX 220 Z 22 SE GMPT E-15

5

History of On Board Diagnosis(OBD)

On Board Diagnosis was introducedin the early 80’s using flash codes.In 1988, California State (USA)required all manufacturers to providea system, that could identify a faultin an Electronic Control Unit (ECU),or the components connected tothis ECU. This was the introductionof the OBD l.

For Opel, OBD was introduced in1985 on the C13LZ in the Corsa A.This system stores a DTC if anelectrical defect is detected on acomponent or a reducedfunctionality of this component hasbeen recognised. The system iscapable of recognising DTC’s,storing DTC’s as well as displayingthe DTC and its status.

In Model Year 1996, OBDstandardisation was introduced forall cars in regards to the indicationof DTC’s on certain components.Furthermore the communicationprotocol between diagnostic testerand ECU was standardised as wellas a 16-pin diagnostic link.

At the same time these standardswere set for OBD ll and in 1996 allcar manufacturers were required tomeet these standards.

In MY 2001, the term ECU has nowbeen superceeded by theabbreviation PCM = PowertrainControl Module.

On Board Diagnosis

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OBD ll is required to monitor andperform diagnostic tests on vehicleemission systems.If the emissions were to rise above1-1 ½ times the FTP (Federal TestProcedure) standards, then amalfunction indicator lamp (MIL)must be illuminated. The DTC’swere also standardised as of ModelYear 1996.

The next step was to create asystem that not only reduces theemissions, but also checks emissionrelevant components, for a givenperiod. The OBD provides an in-service conformity so the cars canbe monitored for a period of 5 yearsor 80000 km. As of Jan. 2005 even100.000 km.How this in-field conformity is goingto take place is, has not beendecided yet.

OBD systems

HC CO NO x HC+NO x

EWG 1992 2,72 0,97EG 1996 2,2 0,5EURO III 2000 0,2 2,3 0,15EURO IV 2005 0,1 1,0 0,08

Emission output in g/km

7

Engine Telltales

It is vital that the after-salesorganisation stress the importanceof the engine telltales to thecustomer. Correct operation of theemission control system must beguaranteed for 5 years/80000 km(Euro3) and in the future, 5 years/100000km (Euro IV). Futurelegislation may mean that thevehicle manufacturer could be heldresponsible for certain failures withinthese periods.

Malfunction Indicator Light(MIL)

When deviations are recognised,compared to the fixed values, acorresponding DTC will be stored inthe PCM memory.• When an emission related DTC

is recognised once, twice orthree times, the MalfunctionIndicator Lamp will be activated.(MIL Steady ON or flashing)

• The Malfunction Indicator Lampinforms the driver aboutemission relevant failures,exceeding of emission standardsor possible catalyst damage.

When fault exists the MIL operatesin two modes:

Mode 1

When the ignition is switched ONand during cranking the MILilluminates as a function control.Once the engine is running (at idle)the MIL extinguishes, assuming noMIL request is sent from the PCM.When an emission related failurehas been detected for the first,second or third time, the MIL will beilluminated and a DTC stored in thePCM.

Mode 2

When a DTC type A misfire isdetected the MIL blinks as long asthe fault exists. Reducing the engineload will stop the MIL flashing but itwill remain ON.

In both cases the driver is advisedto visit an Opel/Vauxhall servicecentre.

In normal operation the MIL controlindicator lights up when the ignitionis switched on and remainsilluminated during starting. It thengoes out when the engine hasstarted.

Depending on the system, the MILwill be switched off if the fault doesnot re-appear within a certainnumber of warm-up or drive cycles.

Engine Electronics Telltale (EET).

The EET illuminates when a systemor component failure is recognisedby the PCM. The EET has fivefunctions:• Non-emission related engine

electronics failure.• Immobiliser fault warning.• Pre-warning of DTC's without

MIL illumination.• Low grade MTA fault• CAN Auto-trans fault

Non-emission related engineelectronics failure.

Continuous illumination of the EETinforms the driver of an enginemanagement failure and theemergency program takes over.This program allows the vehicle tobe driven but at reducedperformance and with higher fuelconsumption. Although switchingthe engine OFF and ON again mayre-set the telltale, repeatedillumination indicates that the drivershould seek assistance from anOpel/Vauxhall service centre.

Immobiliser fault warning.

When the ignition is switched ON, aflashing Engine Electronics Lampindicates that an immobiliser fault ispresent.

Telltale lamp

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Pre-warning of DTC's withoutMIL illumination

Where a system requires a fault tobe registered more than oncebefore the MIL is illuminated, it ispossible for DTC's to be presentwithout MIL illumination. In thesecases the EET can highlight pendingfault conditions.When DTC's are pending the EETwill remain illuminated as long as theignition is switched ON and theengine is not running. This allows aquick decision to be made on theneed to carry out further checks forDTC's. The MIL will still extinguishafter 4 seconds.

Note: It is not normally possible forthe MIL and EET to be illuminatedat the same time.

Low grade MTA Fault

Usually related to a poor selectionproblem i.e. clutch temperature toohigh.

CAN Auto-Transmission Fault

Now used as the sole telltale for allauto-transmissions which have acontrolled area-network busmessaging system in use.

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Consequences for the Aftersalesorganisation

The sophisticated nature of thePCM's fitted to the latest generationof Opel/Vauxhall vehicles has anumber of implications for the ownerand aftersales organisation. It ispossible that unnecessary problemsmay occur if certain procedures arenot followed.

The PCM's all incorporate a learningprocessor. Where the power supplyhas been disconnected from thePCM the following proceduresshould be adhered to when re-connecting the supply to allow thelearning process to be initialised:

••••• Motronic ME 1.5.5.

After the power is re-connected,switch the ignition ON and wait for20 seconds before attempting tostart the engine. Failure to followthis procedure will result in theengine failing to start (cranks OK). Insome cases the engine will start butthe idle speed may fluctuate wildly.

••••• GMPT E - 15

After the power is re-connected,switch the ignition ON and OFF threetimes before attempting to start theengine. Failure to follow thisprocedure will result in the enginefailing to start even though it cranksOK.

••••• HSFI 2.1

No special procedures but the ignitionmust be OFF when disconnectingand re-connecting the power supply.

EOBD terms

••••• European On Board Diagnosissystem (EOBD)

A diagnostic system built into theengine management PCM that isable to detect and store emissionrelated failures. The system must becapable of indicating the probablecause of the fault.

••••• Malfunction Indicator Lamp(MIL) Emissions Telltale

Check light in instrument panel thatindicates the presence of systemfaults.

••••• Engine Electronics Lamp(EET)

Check light in instrument panel thatindicates faults in the engineelectronics or immobiliser systemsnot normally associated withemission sensitive faults.

••••• Diagnostic Trouble Code(DTC)

Alpha-numerical codes indicatingfault area. Normally only visible using(TECH 2).

••••• Warm-up cycle.

Period of operation between enginestart and when the coolanttemperature reaches 71oC, duringwhich the temperature hasincreased by at least 2OoC.

••••• Driving cycle.

A vehicle operation phase thatincludes engine start, acceleration(driving), deceleration and engineshut-off.

••••• System readiness code.

Indicates that a complete on boarddiagnostic test has been carried outsince erasing the DTC's.

••••• Freeze frame.

Historical record of conditions at thetime a DTC was recorded. Therecord is stored for the highestpriority DTC and the data can beviewed using TECH 2.

••••• Diagnostic error.

Error which can be detected by alldiagnostic routines which have tobe executed at least once peremission test cycle.

••••• Comprehensive componenterror.

General errors that can be detectedfor all sensors, actuators andcomponents not covered by otherdiagnostic functions.

••••• CAN communication error.

Errors detected in CANcommunication systems.

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The Malfunction Indicator Lamp(MIL) control confirms to legislativerequirements.

The MIL will be illuminated if:

• The level of misfire is sufficient toresult in catalytic converterdamage under the currentoperating conditions.

Note: in this case the MIL will flashonly as long as the fault is present.More information about the MILoperation is covered later.

• The self-test of the PCM hasfailed.

• Ignition is switched on( position“lll”) with the engine not running(lamp check)

• An emission related fault occursin two or three consecutivetrips.

MIL (Malfunction Indicator Lamp)

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EOBD uses an additional telltale fornon emission-related defects, calledthe Engine Electronics Telltale(formerly known as the ServiceVehicle Soon SVS lamp)

This telltale illuminates when adefect arises which is notnotnotnotnot emissionsrelated.

Engine Electronic Teltale

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The chart below is an example ofhow the internal logic determines ifa readiness code is set.

Diagnostic Trouble Code Types

When a Service Readiness Test isnot passed a matching DTC isstored. All DTC‘s are related to acertain diagnostic test. The PCMdetermines the DTC to be storedbased on the failure of a diagnostictest. Diagnostic tests must fail inone, two or three consecutive tripsbefore the MIL illuminates! Thisdepends on the system and theimportance of the sub system thatis diagnosed.

• Freeze-Frame.The Diagnostic memory in thePCM records certain vehicleoperating conditions when anemission related DiagnosticTrouble Code (DTC) is stored asa history DTC. The PCM onlystores one Freeze Framerecord. Freeze Frame data isstored for the first failed test thatsets the DTC and may alsoilluminate the MIL.

• Failure Record.Where DTC is stored the PCMstores a DTC Failure Recordtoo. This is an extensive data-listthat consists of a large amountof parameters (appr.12) that arederived from the availableparameters from the PCM datalist. The Failure record is extrainformation that is used in caseof a problem.

Trouble codes

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There are five main types of troublecode types:

1. Type A - has the potential todamage the catalyst if the PCMdoes not intervene.

2. Type B and E - result inincreased emissions likely toexceed required standards.

3. Type C - related to the engineelectronic system only.

4. Type D (or Cnl) - related to theengine electronic system only, nowarning lamp.

Note : None of the above applies toAgila with Motronic ME 1.5.5.

The characteristics of each DTCtype are slightly different in themanner that data is stored and howwarnings are given:

Type A• Emission related.• First failure trip illuminates MIL.• Stores a Failure record that is

updated each drive cycle the testfails.

• Stores a DTC on the first trip witha failed test.

• Stores a Freeze frame on the firsttrip with a failed test.

Type B• Emission related.• Second consecutive failure trip

illuminates the MIL.• Stores a Failure record that is

updated each drive cycle the testfails.

• Stores a DTC on the secondconsecutive trip with a failed test.

• Stores a Freeze frame on thesecond consecutive trip with afailed test.

Type C• Not emission related.• First failure trip illuminates EET/

SVS lamp.• Stores a Failure record that is

updated each drive cycle the testfails.

• Stores a DTC on the first trip witha failed test.

• No Freeze frame.

Type D (or Cnl)• Same as Type C, but no warning

lamp illumination.

Type E• Emission related.• Third consecutive failure trip

illuminates the MIL.• Stores a Failure record that is

updated each drive cycle the testfails.

• Stores a DTC on the first trip witha failed test.

• Stores a Freeze frame on the firsttrip with a failed test.

DTC type DTC type DTC type DTC type DTC type DefinitionDefinitionDefinitionDefinitionDefinition A MIL ON and DTC stored at first fail report B MIL ON at second consecutive trip, DTC stored at the

first trip C Engine Electronics ON and DTC stored at the first fail E MIL ON at third consecutive trip, DTC stored at the first

trip D(Cnl) Engine Electronics DTC stored ( No lamp ON)

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Test cycle for EUR0 III

European Type approval

Engine Type approval testing iscarried out on a dynamometer. Thetest consists of selected drive cycleswhilst the exhaust gas is beinganalysed. The manufacturer has toprove that this test can be runthrough twice without the vehicleexceeding the prescribed emissions.The test consist of the followingsteps;

Step 1 (urban cycle, to be run 4xin a row)

• Effective running time: 195seconds

• Distance travelled: 1.013km• Average speed: 19 km/h

Step 2 (sub urban cycle, to be run1x)

• Effective running time: 400seconds

• Distance travelled: 6.955km• Maximum speed: 120 km/h• Average speed: 62.6 km/h

The graph below shows typical Eurodrive cycle test (urban).

The Euro 4 test begins to measureemissions as soon as the enginestarts.Note: The Euro 3 method starts tomeasure emissions 40-secondsafter the engine starts running.

Cyclic test

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OBD

For OBD, some systems andcomponents will be checked onceevery drive-cycle. Others arechecked permanently.

Continuous check.

The systems that are checkedcontinuously, are temperaturedependent and will be checkedimmediately after a 200 C start. If adefect on one of these systemsoccurs the emission telltale will beilluminated.

The following systems are checkedcontinuously.

• Misfire detection.• Injection time.• Exhaust emission relevant

components.

Cyclic test

Those systems that are checkedupon once a drive cycle, will onlyregister the defect if certain speed,load, temperature conditions havebeen achieved. It is not possible tocheck the system, by simplystarting the engine and switching itoff again.

The following systems are checkedonce a drive cycle:

• Working of the oxygen sensors• Working of the catalytic

converterNote: Under some drivingconditions not all required conditionsare achieved and therefore not allchecks will be carried out.

Warm-up cycle

Warm-up cycle conditions arefulfilled if the engine temperaturereads a certain temperature. (710C,with a minimum temperatureincrease of 200C ).If the sensor is damaged thetemperature will be calculated usingback-up values.

Driving cycle

A driving cycle consists of startingthe engine, exceeding the idlespeed (driving), decelerating andswitching OFF the engine.

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Misfire

Misfire is when an ignition(combustion) in a certain cylinderdoes not take place, caused byeither a fuel, ignition or compressionproblem. This lack of combustionresults in unburned mixture enteringthe catalytic converter. This mixturecan potentially destroy the catalyst,and is also harmful to theenvironment. This incident isdetected by the system to preventeven higher exhaust emissions.

This graph above is an exampleof how the post catalystemissions of HC, CO and Noxare effected as a result of acombustion miss.

Misfire monitoring is based on theprinciple that the crankshaftrotational velocity fluctuates as eachcylinder contributes power input.When the engine misfires, thecrankshaft slows downmomentarily. The PCM monitorscrankshaft rotational velocity usingthe crankshaft sensor.

To provide a reliable crankshaftangle measurement, an accuratereference period has to bemeasured. The crankshaft sensordisc and crankshaft sensors aresubject to production tolerances.This can result in inaccuratemeasurements. The tolerances foreach disc vary and therefore haveto be learned by the PCM whichpre-determined a calculated error.The calculated error allows theengine control unit to accuratelycompensate for reference periodvariations. These system variationvalues are stored in the non-volatilememory after the learning has beenperformed. This procedure is calledCCCCCrank AAAAAngle SeSeSeSeSensing (CASECASECASECASECASE, CASElearning). The following PCM’sperform this CASE learning, underthe described circumstances.

• HSFI 2.1; CASE learning isperformed under drivingconditions and during a fuel cut-off period (DFCO).

• GMPT E15; CASE learning isperformed using TECH 2,additional functions.

• The PCM GMPT E15 requiresCASE learning if the followingcircumstances have takenplace:-

• New PCM has been fitted.• DTC.P1336 present (malfunction

crank angle sensing).• PCM has been exchanged• CPS renewal• New crankshaft

When the coolant temperaturereaches 800 C, the engine speedsup from Idle to 4000 rpm. When theengine speed reaches 4000 rpm theDeceleration Fuel Cut Off (DFCO) isinitiated and the measurement ofthe disc reference period takesplace.

The camshaft sensor is used forcylinder identification during thisprocedure.

OBD requirements concerningmisfire detection.

The ECU is capable of recognisingthe severity of misfire. EOBDrequires a system that detectsmisfire, which may result inexceeding of the exhaust emissionlimits. The interest for carmanufacturers is that the catalyst isnot damaged. The conditions underwhich the exhaust emission limitsare exceeded are registered. Whenmisfire occurs to such a level thatthe exhaust emission limits areexceeded, the affected cylinder isidentified and a fault is reported. Ifthe misfire occurs again (one orthree times depending on theengine management system used)under the same conditions the MILilluminates and the Freeze Frame isstored.

Misfire detection

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The method used for determiningthe severity of misfire is variableamong the engine managementsystems used for the Opel/Vauxhallengines.

Two misfire characteristics areidentified by the PCM:

1. Catalytic converter damaging:

A level of misfire sufficient toresult in a catalytic converterdamage under the currentconditions.

2. Emission threatening:

A level of misfire resulting inexceeding exhaust emissionlimits.

Another approach is to make acomprehensive map. The map ismade using several engineparameters such as engine speed,coolant temperature, engine loadand the decisive one, the calculatedtemperature of the TWC. The mapis obtained by applying errors (I.E.an interrupted injector) in the enginemanagement system and bymeasuring the temperatures in thecatalyst under these circumstances.There is no common method todetermine the severity of the misfireor what type of misfire is present.

Every manufacturer of any enginemanagement system interpretsmisfiring in its own way.The following table shows thedifferences.

Note:

In the following circumstancesMisfire detection is not executed(depending on calibration):• If the engine speed exceeds

6000 RPM.• If the tank contains less than

20% of its total capacity (Onlythe Z22SE GMPT E 15).

• In the first 5 seconds after thestart.

• If the battery voltage dropsbelow 5 Volts.

• Driving on very bad roads*.

*The crankshaft sensor recognisesrough road conditions via internalevaluation logic.

Thresholds to determine the type of misfire for the different enginemanagement systems

Misfire Motronic monitoring ME 1.5.5 HSFI 2.1 GMPT E 15 Type A >9% >5% map Type B map Type D 5-9% Type E 4%

Misfire Monitoring Motronic Simtec DTC Type B/D/E ME 1.5.5 HSFI 2.1 MS 71 GMPT E-15 Driving cycles before MIL ON 3 3 3 2

Driving cycles before MIL ON. Misfire monitoring

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Electronic accelerator pedal

E-gas was first introduced on theY16XE and Y22XE engines. Thissystem is designed to assist theseengines in passing the new emissionregulations. The Y16XE and theY22XE are D4 emission regulationcompliant. The Z16XE and Z22SEare Euro IV compliant.Using the E-gas system allowsbetter control of the mixture, abetter control of the mixture meansa better control of the emissions.

The main components of the E-gassystem are:

• Accelerator module• Throttle body

With the introduction of the E-gassystem the mechanical connectionbetween the Accelerator andThrottle body disappeared. Thissystem is a so-called "Drive by wire"system. The throttle valve is nowopened and closed by the throttlepositioner.

The signals and components the E-gas system functions on, are:

• Pedal position potentiometer 1Pedal position potentiometer 2

• Throttle potentiometer 1• Throttle potentiometer 2• Throttle positioner

The next signals are indirectly usedon the E-gas system, these signalsare used in the case of acomponent/signal breakdown.

• Mass Air Flow sensor• Brake light switch• Vehicle speed sensor

E - Gas throttle body system

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Pedal position sensor

The Pedal position sensor consiststwo potentiometers. These twopotentiometers both require aseparate power supply and ground,this is to decrease the chance ofcomponent failure in the event of anelectrical fault.

The pedal position sensor isconnected to the wiring harness byone connector.

The voltage of both potentiometersincreases with operation. The pedalposition potentiometer 1 operatesbetween 0 - 5 Volts. The pedalpotentiometer 2 (this potentiometerchecks potentiometer 1) operatesbetween 0 - 2,5 Volts. The systemis designed so that when itsoperating properly the voltage ofbothpotentiometers is never equal. Thevoltage of potentiometer 1 mustalways be greater than the voltageof potentiometer 2.

2 0

Throttle body

The throttle body contains twopotentiometers and the throttlepositioner. The potentiometersoperate differently to the pedalposition potentiometers.

Two throttle valve potentiometersare fastened to the throttle bodyand are seated on one shafttogether with the throttle valve.Voltage is supplied to bothpotentiometers via one commonpositive and negative connection.

The voltage of throttle potentiometer1 increases as the throttle opens,the voltage range of thepotentiometer is 0 - 5 Volts. Wereas, throttle potentiometer 2 shows adecrease in voltage when thethrottle opens. The voltage range ofthis potentiometer is 5 - 0 Volts.

As we can see there is one point onthe graph where the voltage of bothpotentiometers is equal. At this pointthe ECU reads the MAP sensor forthe required information on theY16XE, or the mass air flow meter iffitted.

2 1

PWM signals

Idle speed

Throttle position at idle speed

This graph shows the PWM signalfrom the PCM to the throttlepositioner at idle speed. This signalmakes sure that the throttle valve isclosed a little until the programmedidle speed is reached.

When the pedal position sensor isoperated, the PCM receives a signalfrom the pedal position sensorpotentiometers. The PCMcalculates the required output signalfor the throttle positioner. Themovement of the throttle valve ismonitored by the

throttle body potentiometers. In theevent of a fault arising it is possiblefor the throttle positioner to beswitched off

When the throttle positioner isswitched off, the valve rests at apreset position. The throttle valve isforced into this preset position by aspring. In this preset position thethrottle valve is partially open,allowing an engine speed of 1500RPM. This is to drive the vehicle andensure a good engine breaking onoverrun.

The signal which the throttlepositioner receives from the ECU isa PWM (Pulse Width Modulation)signal. As mentioned before thethrottle valve is forced into a presetposition when it is switched off ordisconnected (1500 RPM). At thisposition the valve opening is greaterthan the opening at idle speed (800RPM). For the engine run at idlespeed the valve must be closed alittle. On acceleration the valve mustfirst go back to the preset position inwhich the spring forces it. After thisposition the valve must be openedto reach the speed the driverdemands.

So first, the valve must be closed alittle, and when accelerating, thevalve must be opened.

The opening and closing of thethrottle valve is carried out by thethrottle positioner that works in twodirections.

Drawing of throttle valve in threepositions with descriptions

2 2

1400 -1500 RPM

Throttle position between1400 - 1500 RPM

On light acceleration the throttlevalve is approaching the presetposition. The force required tomaintain the throttle valve in thisposition is low (low spring pressure).For this reason the pulses widthsare reduced in comparison to at idlespeed.

On further acceleration the throttlevalve reaches the preset position.The spring pressure becomesneutral. For the throttle valve toopen further, the throttle positionermust force the spring in theopposite direction.

For this to happen the throttlepositioner needs to work in theother direction. This is achieved bychanging the PWM signal frompositive to negative.

1500 - 1600 RPM

Throttle position between1500 - 1600 RPM

This graph shows the PWM signalafter the valve has opened a littlefurther than the preset position. Thethrottle positioner works in the otherdirection and the signal changedfrom positive to negative.

1600 - RPM

On increased acceleration, thethrottle valve opens further until theengine reaches the demandedRPM. The throttle positionermaintains the throttle valve in thisposition (cruise position).

Throttle position above 1600 RPM

This PWM signal maintains thethrottle positioned in this position.This signal is consistent for allthrottle valve positions above thepreset position, as the spring is aconstant rate type.

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Emergency operation modes

In the event of malfunction with theE-gas system, one of the fouremergency operation modes will beactivated.

1. Emergency operation

Opening the throttle valve is limitedto approx. 50% by the enginecontrol unit.

2. Emergency air

In emergency air operation, thethrottle valve servo motor isswitched on and off with withoutelectricity, thus severely restrictingthe operating capacity of thevehicle. The throttle valve is openedapprox. 33% by spring force. Theaccelerator pedal module controlsthe engine speed (max. 3000rpm)by adjusting the fuel injectionquantity.

3. Increased Idle Speed

If the idle speed is increased, theengine idle speed is maintained at aconstant level (approx. 1500rpm) bythe control unit, irrespective of load.the accelerator pedal module hasno control over the engine speed.

4. Engine off

The ignition and fuel injection areswitched off in the 'Engine off'emergency operation mode. It is notpossible to continue driving.

Possible faults and their impact are listed in the following tablePossible defect Emergency Emergency Increased Engine

operation air idle speed offPedal sensor 1(driver requirementspotentiometer) XPedal sensor 2(monitoring potentiometer) XThrottle valve potentiometer 1 or 2 X5 V voltage supply to pedal sensor 2 or throttlevalve potentiometer 1 XThrottle valve potentiometer 1 or 2 XInterruption/short-circuit in throttle in throttlevalve motor XInternal fault in engine control unit, throttle valveactuation XDeviation of throttle valve position from actualpedal sensor value XIntake pipe pressure sensor XPedal sensors 1 and 2 X5 V voltage supply to pedal sensor 1, throttlevalve potentiometer 2 or intake pipepressure sensor XInternal faults in the engine control unit,central processing unit XCrankshaft sensor XMultiple fault X

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Starting catalytic converter,Y22XE

The Y22XE engine in the Omega-Bis equipped with an additionalcatalytic converter (starting catalyticconverter) which is installed near tothe engine. Compared to the maincatalytic converter(2), the startingcatalytic converter (1) is of asignificantly smaller construction.Due to the close proximity to theengine and the smaller construction,the starting catalytic converterachieves its operating temperaturesignificantly faster and is thus morequickly functional than the maincatalytic converter. This modificationcontributes significantly to thereduction of exhaust gas emissions.

Catalytic convertor with twin O2 sensors

2 5

Oxygen sensors, Y22XE

The Y22XE engine is equipped withtwo heated oxygen sensors.The first oxygen sensor (1) isinstalled directly in front of thestarting catalytic converter anddetermines the remaining oxygencontent of the non-purified exhaustgases.The second oxygen sensor (2) isinstalled behind the main catalyticconverter and determines theremaining oxygen content of thepurified exhaust gases. The secondoxygen sensor thus monitors thefunction of the exhaust gas controlsystem.

2 6

Short Term and long Term Fuel Trimdata is read with a scan tool andcan be useful information whendiagnosing engine performanceconditions. Short Term/long TermFuel Trim data is a reflection of thePCM changing the pulse width ofthe fuel injectors to keep the air/fuelratio of the engine as close to theoptimal 14.7:1 as possible. Theimportant difference between themis that the Short Term Fuel Trimindicates current changes of short-term duration, while long Term FuelTrim indicates learned changes overa long-term period.

Short Term Fuel Trim

Short Term Fuel Trim is part of asystem that helps to make minor,temporary corrections to the air/fuelmixture when the system is inclosed loop.

The Short Term Fuel Trimcontinuously monitors the outputvoltage from the oxygen sensor. Ituses 0.45 volts (450mV) as areference point. In Closed loopoperation, 02S signal voltage shouldvary constantly, from a high ofapproximately 0.9 volts (900 mV) toa low of approximately 0.1 volts (100mV). When the PCM reads outputvoltage constantly crossing backand forth across the 0.45 voltreference mark, it can continuouslyadjust fuel delivery to keep the air/fuel mixture as close as possible tothe ideal 14.7: 1 ratio.

Short Term Fuel Trim numbers arebased on a percentage value. Thescale ranges between -100% and+100%, with 0% as the baseline.There is an operating tolerance of-/+10%.

If the Short Term value climbsabove the +10% tolerance, thePCM is adjusting for a leancondition, so more fuel is beingadded to the engine. If the ShortTerm values fall below the -10%tolerance, the PCM is adjusting for arich condition, so less fuel is beingadded.

The Short Term Fuel Trim number isan indication that the PCM iscompensating for changing fueldemands.

If the PCM see's the Short TermFuel Trim reading are continuouslyindicating a maximum high or lowpercentage value, then the PCM willask the Long Term Fuel Trim toapply its 'learned' fuel correction.This may mean that the Short TermFuel Trim goes back to its baselinesettings, but will continue to updatethe Long Term Fuel Trim.

Short term/long term fuel trim

2 7

Long Term numbers are also basedon percentage value, with 0% asthe baseline and the operatingtolerance between -15% and+15%. A block of cells containsinformation arranged incombinations of engine rpm andengine load for the full range ofvehicle operating conditions. Asconditions change, the PCMchecks the appropriate block fordata to use in calculating correctinjector pulse width. Ideally, eachblock value would be 0%. If theShort Term Fuel Trim is far enoughfrom 0%, the Long Term Fuel Trimchanges its value and resets theShort Term to 0%.

Long Term Fuel Trim

Long Term Fuel Trim shows thePCM "learned" fuel correction. Thelong Term Fuel Trim reading showshow much the PCM hascompensated. Even though theShort Term Fuel Trim can make awide range of fuel correctionsfrequently, long Term Fuel Trim canIndicate a trend In the lean or richdirection the Short Term is taking.Long Term Fuel Trim can make asignificant fuel delivery change inthat direction after a longer period oftime.

Long term fuel trim example

Long term fuel trimNo correction

Long term fuel trimcorrecting for a slightly lean

exhaust

Long term fuel trimcorrecting for a slightly rich

exhaust

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2 8

Short Term and Long Term FuelTrim values can help the technicianidentify actual rich and leanconditions caused by problemsexternal to the fuel injection systemand related sensors.

Lean

• High NOx• Stumble and stalls• Surges• Poor performance

Rich

• High HC, CO• Black smoke• Catalytic converter odour• Fouled plugs• Sooty exhaust

Oxygen Sensor

Lean (low 02 Volts) Rich (High 02 Volts)

Short or Long term fuel trim is high Short or Long term fuel trim is low(above 128) Possible code set (below 128) Possible code set

Oxygen sensor verifying lean condition Oxygen sensor being 'Tricked' richCause: Fuel system not controlling Cause: not enough air in the exhaustCheck for: Check for:• Low fuel pressure • Too much EGR• Vacuum leak, intake manifold leak • Oxygen sensor ground loose or dirty• Lean injectors (restricted) no star washer• MAF/MAP Fault • Oxygen sensor poisoned

Oxygen sensor being 'Tricked' lean Oxygen sensor verifying rich conditionCause: Too much air in the exhaust Cause: Fuel system not controllingCheck for: Check for• Secondary air injection • High fuel pressure• Cracked or leaking exhaust manifold • Restricted fuel return line• Cylinders not firing, sending unburned • Leaking injector

Air/fuel into the exhaust • Canister purge continuously purging• Restricted air cleaner• Oxygen sensor contaminated• Fuel contaminated oil• MAF/MAP fault

2 9

Fuel trim conversions

Fuel trim diagnostics - EOBD

To meet EOBD requirements, fueltrim information in the Data List willbe displayed using percentages.This differs from the way fuel trimhas been traditionally displayed onthe scan tool. Refer to the figurebelow for a cross- reference of fueltrim numbers and percentages(figure 4-32). Short-term and long-term fuel trim function the same asin the past, only their measurementunits will differ. Fuel trim values thatare +10% or -10% are an indicationthat the PCM is maintaining properfuel control.

Positive percentage conversion:

128 + (1.28 percentage)Example: to convert +20% tocounts the formula would be 128 +(1.28 x 20) = 154

Negative percentageconversion:

128 - (1.28 percentage)Example: to convert +20% tocounts the formula would be 128 -(1.28 x 20) = 102

Conversion of fuel trim from percentage to counts

Fuel trim count to percentage conversion chart

3 0

OBD tests

Even though the OBD strategiesare different in several enginemanagement systems, all have tomeet prescribed tests.The following exhaust emissionrelated tests are compulsory forOBD:

• Catalytic converter efficiency• Misfire• Fuel system• Oxygen sensors operation• Secondary air operation• Evaporation system• EGR system• Powertrain control module

(PCM)

Catalytic converter efficiencymonitoring

According to the OBD regulations,the catalytic converter’s efficiencymust be monitored once per drivecycle. The catalyst oxidises CO andHC and reduces NOx. Theconverter also has the ability tostore excess oxygen and to releasethe stored oxygen in order toimprove the oxidation and reductionperformance.

The Oxygen Storage Capacity(OSC) is a reference for thecatalyst’s efficiency to controlemissions. The PCM monitors thisprocess by using a heated oxygensensor (HO2S2) that is fitted afterthe three-way converter (TWC). Thissensor is called a Monitor Sensor.

Catalyst monitoring; cruising.

To determine the Oxygen StorageCapacity (OSC) of the Three-WayCatalytic Converter (TWC), allcomponents involved must be atoperating temperature and thevehicle must cruise long enough

to record multiple oxygen samples.During these tests the PCMchanges the Air/Fuel ratio viainjection pulse width variation. As aresult of this the monitor sensor(HO2S2) output varies too. The timeis measured between theadaptation of the Air/Fuel ratio andthe output change of the monitorsensor (HO2S2). This value iscompared to the calibrated values inthe Powertrain control module(PCM). It is evident that this timedepends on the Oxygen StorageCapacity (OSC) of the TWC and is ameasure for the effectiveness of theTWC. If the time measured is tooshort the PCM sets a DTC.

3 1

Z 18 XE DOHC I Petrol Engine

The Z 18 XE DOHC I petrol enginefeatured in the Astra-G, Zafira andVectra-B is a further advancementof the Opel/Vauxhall ECOTECengine generation and is based onthe X 18 XE1 DOHC petrol engine.The most significant new features inthe Z 18 XE petrol engine are thecomponents which have beenmodified to satisfy the requirementsof the Euro 4 exhaust emissionsstandard.

The main differences between the Z18 XE and the X 18 XE1 are listed inthe table below.

Management system overview

Base engine: X 18 XE1 Z 18 XE

Crankshaft without increment disc Increment disc on crankshaftweb 8

Vibration damper with increment disc without increment disc

Exhaust manifold conventional exhaust manifold with weldedcatalytic converter

Engine management Simtec 70 Simtec 71system

Throttle body conventional designed for electronicaccelerator pedal

EGR valve available not used

Injectors with air containment with air containment, butnot used

Exhaust emissions 94/12/EU, EU 96 98/96EU, Euro 4 Level Bstandard

3 2

Engine Management System,Simtec 71, Z 18 XE

The Z18XE engine is equipped withengine management system Simtec71. The basis for this enginemanagement system is alreadyused in the Vectra-B X 18 XE1.

The new features of the Simtec 71are listed below:

• New accelerator pedal module(electronic accelerator pedal)

• Throttle valve module (electronicaccelerator pedal)

• New crankshaft pulse pick-up• 2nd Oxygen sensor for monitoring

exhaust emission control• Catalytic converter closer to the

engine• Fuel system without return

Z 16 SE OHC 1 Petrol engine

The Z16SE OHC 1 petrol enginethat is featured in the Astra-G is afurther advancement based on theX16SZR OHC 1 petrol engine. Thecylinder block is adopted from theZ14XE/Z16XE. The most significantnew features in the Z16SE engineare the components, which havebeen modified to satisfy therequirements of the Euro 4 exhaustemission standards.

The most important modifications ata glance are:

• Modified cylinder head, based onC14SE/C16SE

• Optimised cylinder head gasket• Vibration damper without

increment disc• Modified piston to reduce weight• New intake manifold, intake

manifold injection, satisfies theEuro 4 exhaust emissionstandards

• Exhaust manifold with weldedcatalytic converter

• PCM, composite construction• Camshaft sensor• Wiring harness, engine control

unit - composite construction• Intake pipe pressure sensor• Injection valves with conical jet

twist protector• DIS ignition module• EOBD - functionality in the PCM

3 3

Injectors, Z 14 XE, Z 16 XE

The Z 14 XE- and Z 16 XE enginesare equipped with advanced versionof the injectors (2). The injectors ofthe Multec S (F) 2nd generationhave a modified fuel injectionpattern, resulting in improvedemission and consumption values.Furthermore, the new fuel injectornozzles are equipped with a twistprotector (3). This prevents the fuelinjector nozzle from turning in thefuel distributor pipe (1). The injectornozzles in the Z 14 XE and Z 16 XEno longer have air containment.

Engine Control Unit, Z14XE,Z16XE, Z18XE

The Engine Control Unit Multec-S(F) in the Z 14 XE, Z 16 XE and Z 18XE is a composite design, as in theX 16 XEL engine of the Astra-G andZafira, and is fastened to thecylinder head with a bracket. ThePCM has 2 separate plugconnections for each compact plug.

With the Z 18 XE, the engine controlunit is fastened to the intakemanifold and is equipped with anenlarged flash memory.The principal features of thecomposite-design control units are:

• Installation in enginecompartment possible

• Compact design• Separate wiring harness plugs for

instrument panel and enginewiring harness connectionsmarked K and M (K = karosserieor body harness and M = motoror engine harness).

Composite PCM's have a compactdesign which is insensitive tovibrations, impacts andtemperature. For these reasons it ispossible to use the PCM in theengine compartment. The wiringharnesses can be designed to beshorter.

This design with separate wiringharness plugs enables the bodywiring harness to be disconnectedwithout any problem from theengine control unit when removingand installing the engine.

3 4

Engine Management System,Multec-S (F), Z 14 XE, Z 16 XE

The Z 14 XE- and Z 16 XE enginesare equipped with the advancedversion of the Multec-S (F) enginemanagement system. The basis forthis engine management system isalready used in the Vectra-B MY2000.

The new features of the Multec-S(F) are summarised below andexplained in the subsequentsections.

• New intake pipe pressure sensor• New accelerator pedal module

(electronic accelerator pedal)• Throttle valve module (electronic

accelerator pedal)• Modified fuel injector nozzles• Modified linear exhaust gas

recirculation valve• New crankshaft pulse pick-up• Modified camshaft sensor• 2nd Oxygen sensor for monitoring

exhaust emission control• Catalytic converter closer to the

engine• Fuel system without return

Y 26 SE DOHC II Petrol Engine

The Y 26 SE DOHC II petrol enginethat is featured in the Vectra andOmega is a further advancement ofthe Opel ECOTEC enginegeneration and is based on the X 25XE.

The most important modifications ata glance are:

• Electronic accelerator pedal• OBD -Functionality in the engine

control unit• 2 starting and 2 main catalytic

converters with 4 oxygen sensors• PCM of compositedesign ME 3.1.1• Injectors• Throttle body• Spark plug change interval every

120,000 km• Ignition module• Fuel system without return• Cylinder head gasket• Pistons

3 5

Powertrain Control Module ME3.1.1, Y 26 SE

The PCM for ME 3.1.1 has acomposite design. It has 2 separateplug connections for each 64-pincompact plug. A newmicroprocessor is featured.

The principal features of thecomposite-design PCM are:

• Installation in enginecompartment possible

• Compact design• Separate wiring harness plugs for

instrument panel and enginewiring harness connections

• The use of ceramic substratesmakes it particularly compact andreliable

The PCM have separate wiringharness plugs for the instrumentpanel and engine wiring harnesses.This design with separate wiringharness plugs enables the bodywiring harness to be disconnectedmore easily problem from the enginecontrol unit when removing andinstalling then engine.

Injectors (EV 6 C), Y 26 SE

The injectors EV 6 C are of acompletely new design. They setnew standards with regard tofunction, quality and installationflexibility due to new functionalfeatures and manufacturingmethods. They are characterised byvery good hot-start processes andcorrosion-resistance.

In addition, they have aircontainment. The air containment isan auxiliary function to furtherimprove the jet atomisation of theinjector. The necessary air isbranched off upstream of thethrottle valve and supplied to theinjectors. The low pressure in theintake manifold is utilised as thedrive for the air containment. The airis supplied to the outlet area of thenozzle hole disc via a aircontainment attachment. The airmoves at very high speed due tothe narrow gap at the air outlet, andthe fuel is finely atomised as the airis mixed in. The air/fuel mixture flowsto the intake manifold at highspeed.

The injectors are provided withconical jet nozzles. Individual fueljets pass through the openings ofthe nozzle hole disc. The fuel jetstogether form a conical jet. Theangle containing the fuel quantity isdefined as a the Jet Angle.

Ignition Module, Y26SE

The ignition modules in the Y 26 SEare arranged directly above thespark plugs and contain thefollowing components:

• Wiring harness plug from theengine control unit

• One single ignition coil for eachcylinder

• Integrated spark plug connector

••••• Service

Observe the safety regulationswhen working on high voltagecomponents.

3 6

Z 20 LET DOHC II Turbo Engine

The Z 20 LET DOHC II turbo enginethat is featured in the Astra-G is afurther advancement of the Opel/Vauxhall ECOTEC enginegeneration and is based on the Y 22XE and the X 20 XEV. The essentialmodifications serve to satisfy theEuro 4 exhaust emission standard.

The Z 20 LET DOHC-II turbo enginewith balancer shafts in the AstraCoupe simultaneously fulfils therequirements of sporty performanceand high comfort. Compared to thenaturally aspirated engine with thesame capacity, the maximumtorque has been increased by 30 %and the power by 40 %. Themaximum torque of 250 Nm isavailable in the entire speed rangebetween 1950 and 5300 rpm. Themaximum power is 140 kW and isreached at a nominal speed of 5400rpm. A very good response can beachieved even at low speeds due toselection of a suitable turbocharger.The vehicle offers a high degree offun while driving due to the excellentflexibility.

The most important componentsthat have been adopted andmodified are listed in the list below:

• Engine block, flywheel,crankshaft with a stoke of 86 mmand a ring gear for balancershafts adopted from the X 20 XEV

• Cylinder head and ignitioncassette, adopted from Y 22 XE

• Con-rod, adopted from C 20 LETwith floating piston pin

• Temperature controller, heatexchanger, intake manifold,ambient pressure sensor,camshaft gear and camshaftsensor, adopted from the X 22 XE

• PCM, adopted from the Z12 XE, composite design with

electronic accelerator pedal• Mass air flow meter, adopted

from the X 20 DTL• Exhaust valves, adopted from the

X 30 XE (sodium cooled)• Balancer shaft unit, like X20XEV• Electronic accelerator pedal• EOBD - Functionality in the

engine control unit• Electronic throttle body (ETC)• Turbocharger, integrated in the

exhaust manifold• Intercooler• Piston with recess, CR 8.8 : 1

Air Cleaner

3 7

Engine Management System ME1.5.5, Z 20 LET

This engine management systemincludes an electronic throttle valvecontrol based on a torque-orientedfunction structure. The setting of theengine torque is determined thedriver demand and is achieved by acorresponding selection of variables(throttle valve angle, injection time,ignition angle, and waste gateposition of the exhaustturbocharger). The direct ignition iscomposed of four individual ignitioncoils positioned directly on the sparkplugs in the form of a compactmodule strip attached to thecylinder head .

The fuel system is operated at a fuelpressure of 3.3 bar relative to theintake manifold. Injection isperformed sequentially. The mixtureis controlled by an oxygen sensorthat is fitted in the exhaust manifoldbefore the pre-catalytic converter. Asecond oxygen sensor is fittedbehind the main catalytic converter.This second sensor is used as aguide for diagnostic purposes(EOBD).

The knock control system affectsthe ignition, injection, chargepressure and throttle valve position.It operates adaptively andspecifically for each cylinder.

A combined pressure andtemperature sensor at the output ofthe intercooler is used for chargepressure and mass control. Thesignal of the hot film mass air flowmeter fitted behind the air cleanerassists the charge pressure controland is used for diagnostic purposes,such as detecting leaks. Damage tothe turbocharger from running toofast due to leaks can be preventedusing the charge pressure controlsystem.

Z 22 XE DOHC II Petrol Engine

The X22XE DOHC II petrol engine isa new development within the Opel/Vauxhall ECOTEC enginegeneration, and is based on theY22XE. The most significant newfeatures in the Z22XE are thecomponents, that have beenmodified to satisfy the requirementsof the Euro 4 exhaust emissionsstandard.

Caution:

Vehicles with manual transmissionsare classified according to the Euro4 exhaust emission standard andvehicles with automatictransmissions are classifiedaccording to the Euro 3 exhaustemission standard.

The most important modifications ata glance are:

• EOBD -Functionality in the enginecontrol unit

• Electronic accelerator pedal• Catalytic converter coating• Intake manifold, internal diameter

has been enlarged from 34mm to35 mm

3 8

Power train control module

e.g.

The X 18 XE1 and X20 XEV enginesare equipped with the new Simtec70 engine management systembased on the familiar Simtec 56.5.

The differences between Simtec56.5 and the Simtec 70 in the X 18XE1 and the X 20 XEV at a glance:

Simtec 56.5 Simtec 70 Simtec 70X 18 XE1 X 20 XEV

Ignition coil DIS Ignition coil (4 DIS(dual spark ignition individual ignition coils (dual spark ignitioncoil) with integrated spark coil)

plug connectors)

Fuel pressure Pressure regulator Pressure regulator Pressure regulatorregulator attached to fuel intergrated into fuel attached to fuel

distributor pipe tank module distributor pipe

Coolant Engine control Engine control Engine controltemperature unit unit, engine cooling unit, engine coolingsensor module control unit, module control unit,

Sensor signalfor: Temperature gauge Temperature gauge

Engine control Conventional Hybrid Hybridunit

Camshaft Inductive sensor Hall sensor Hall sensorsensor

Crankshaft Hall sensor Inductive sensor Inductive sensorpulsepick-up

Throttle body Throttle valve Throttle valve adjuster Throttle valvewith: potentiometer and potentiometer and

idle air controller idle air controllerwith bypass duct without bypass duct with bypass duct

Hot film mass External intake air Internal intake air Internal intake airair flow meter temperature sensor temperature sensor temperature sensor

3 9

Camshaft sensor,

1 Camshaft sensor X 18 XE12 Camshaft sensor X 20 XEV

The camshaft sensor (Hall sensor) isused to detect the camshaftposition and provides the cylinderrecognition required for sequentialinjection.

The exhaust camshaft pulley hastwo offset segments built in to itsrim.

The camshaft sensor consists oftwo Hall elements, with oneelement allocated to each segment.

The camshaft sensor is capable ofrecognising the camshaft position assoon as the ignition is "ON", i.e.before the engine is started. Thisallows a 'quick start system' to beused.

The quick start system determinesthe exact fuel quantity to beallocated to each cylinder right fromthe first engine revolution. If thecrankshaft pulse pick-upmalfunctions, a camshaftemergency program is availableallowing the engine to continuerunning.

The segments are located on thefront of the exhaust camshaft pulleyin the X 18 XE1 (illustration G 5083)and on the rear in the X 20 XEVexhaust camshaft pulley.

4 0

Camshaft pulleys

A new camshaft sensor has led tonew camshaft pulleys being installedin the X 20 XEV.

The exhaust camshaft pulley ismarked, as can be seen in theillustration. The rear side of theexhaust camshaft pulley has two180° segments (panels) used by thecamshaft sensor to detect thecamshaft position.

• Service

The familiar Special Service ToolKM-853 can still be used to fix thecamshaft pulleys (camshafts) inposition for maintenance.

1 Intake camshaft2 Exhaust camshaft3 Camshaft sensor4 Exhaust camshaft pulley (rear

side)

4 1

Signal allocation from crankshaftpulse pick-up and camshaftsensor

The crankshaft pulse pick-up disc(increment disc) is a gear wheel witha total of 58 teeth. The gapbetween the teeth is the samewidth as two teeth. The signal fromthe first tooth profile that occurs (1)on the pulse pick-up disc after thetooth gap is 114 ° CA 1) before TDC2) for the 1st/4th cylinder (2)

The signal pattern generated by thecamshaft pulley with the segmentsoffset by 180° means that TDC forthe 1st cylinder occurs 78° CA afterthe rising profile (4) and TDC for the4th cylinder occurs 78° CA after thefalling profile (3).

Ignition sequence: 1-3-4-2I Signal from crankshaft pulse

pick-upII Signal from camshaft sensor

1) CA: Crankshaft angle2) TDC: Top Dead Centre

4 2

Hot Film Mass Air Flow Meter,

Precise measurement of the airmass is essential for exact meteringof the fuel quantity. In order toensure that this requirement issatisfied, the signal from the hot filmmass air flow meter is corrected bythe electronics.

The integration of the intake airtemperature sensor into the hot filmmass air flow meter has led to asimplified wiring harness and areduction in the number ofcomponents. The sensor installedis a precise NTC sensor (heatconductor).

A:Range of air flow mass:

Min. air flow mass 5 Kg/hMax. air flow mass 470 Kg/h

B46 Circuit symbol for hot film massair flow meter.

B:Range of output signal

Min. output signal 0 VMax. output signal 5V

The hot film mass air flow meterused in the X 18 XE1 and X 20 XEVengines is the most importantcomponent for calculation of theload signal. It is known as a"thermal load sensor".

The hot film mass air flow meteruses a dual sensor element. Thefirst sensor (RT) measures the inputtemperature and the second sensor(Rs) measures the air flow mass.

The interplay between the twosensors is regulated by a jumpercircuit (R1 and R2) which can de-couple the measurement of theinput temperature from themeasurement of the airflow mass.

A uniform flow of air to the sensorsis achieved by a honeycombelement (1) and a grid (2) at theintake of the mass air flow meter.

4 3

Crankshaft pulse pick-up

The crankshaft pulse pick-up isresponsible for detecting thecrankshaft speed. The crankshaftpulse pick-up functions on theinductive measuring principle. Thevoltage induced is therefore directlyproportional to the speed of theincrement disc.

In the X 18 XE1, the crankshaftpulse pick-up is attached to a lugon the oil pump and uses thetorsional vibration damper(increment disc) to detect therotational speed.

In the X 20 XEV, the crankshaftpulse pick-up is attached to thecylinder block and uses a pulsepick-up (increment disc) bolted ontothe crankshaft to detect therotational speed.

The crankshaft pulse pick-uptransmits a signal to the enginecontrol unit, which uses it tocalculate the crankshaft speed.

1 Crankshaft pulse pick-upX18 XE1

2 Crankshaft pulse pick-upX 20 XEV

4 4

For the X 20 XEV the bypass idlespeed control known from theSimtec 56.5 is used. The X 18 XE1features an electronic throttle valvepositioner with integrated throttlevalve potentiometer. (see illustration)

The features of the Simtec 70

Both the X 18 XE1 and theX 20 XEV use the Simtec 70 enginemanagement system. Both alsofeature a hybrid Powertrain Module.

The differences between the twoversions used are:

X 18 XE1:

• PCM mounted at the manifold• 4 ignition output stages

X 20 XEV:

• PCM mounted near the battery• 2 ignition output stages (DIS)

The crankshaft sensors areinductive sensors, the camshaftsensors are Hall-sensors.

Engine / engine-management

4 5

GMPT E-15 Ignition system

Description

Compression Sense Ignition is aDirect Ignition System (DIS) with anelectronic detection feature thatuses the different breakdownvoltages between the exhaust andcompression stroke to identifycylinders for sequential fuel control.It has no moving parts and does notrequire timing adjustments.

A typical package includes one two-tower inductive coil for each cylinderpair. an ignition module, and acrankshaft sensor. Compressionsense replaces the camshaft sensorby controlling fuel with a signal thatis devised from the differentbreakdown voltages in thesimultaneously firing cylinder pairs ina DIS system. With a DIS one coilfires two cylinders at the same timethat are 360 degrees apart, one ofthe cylinders is on the compressionstroke the other is on the exhauststroke.

1 DIS ignition module2 Control unit3 Knock sensor4 Crankshaft sensor5 Pulse pick

The breakdown voltages for the twocylinders are different due to thepressure inside the cylinder. Thecompression cylinder's breakdownvoltage occurs about 10-25 KV. Theexhaust cylinder's breakdownvoltage occurs about 5 KV and alittle before the compressioncylinder's breakdown voltage, Thecompression sense circuitrycompares the two and can tellwhich one is on compression. Thisinformation can be used to send apulse that would normally be sentby the cam sensor. It allows for theremoval of a separate cam sensor,and reluctor wheel, This system isused mainly on a DIS but canpossibly be adapted to a coil percylinder system.

Ignition systems

Features Benefits

• Early and precise electronic • Increased fuel economyspark timing

• Elimination of cam sensor • Lower system costand reluctor wheel

• Reduced RFI • Less radio interference

4 6

Ignition module, (exampleZ 18 XE)

The ignition module is a compactcomponent and is located betweenthe two camshafts on the cylinderhead cover, directly above thespark plugs, and contains thefollowing components

1 Wiring harness plug from enginecontrol unit

2 One individual ignition coil foreach cylinder

3 Integrated spark plug connector

••••• Service

The ignition module must only beremoved with the dedicated SpecialService Tool KM-6009, or there is arisk that the module will bedamaged.

Observe all safety measures whenworking with high voltage-bearingcomponents.

4 7

Throttle Body, X 18 XE1

The X 18 XE1 is equipped with anew throttle body with an integratedfully electronic throttle valve adjusterand an integrated throttle valvepotentiometer.

Idle air control in the X 18 XE1depends on the position of thethrottle valve in the full intake airflow and is regulated by the throttlevalve adjuster.

When the accelerator pedal isactuated, the throttle valve ismechanically adjusted via theaccelerator Bowden cable.

••••• Service

The throttle body, throttle valveadjuster and throttle valvepotentiometer can only be replacedas a assembly.

Following replacement of thethrottle body or the PCM theadaptation values for the throttlevalve in the EEPROM of the enginecontrol unit must be deleted usingTECH 2 -see the correspondingChecking Procedures.

1 Wiring harness plug2 Throttle valve housing3 Throttle valve adjuster (B45)4 Throttle valve potentiometer

4 8

Crankshaft pulse pickup,Z 14 XE, Z 16 XE and Z 18 XE

The crankshaft pulse pickup (1) isattached to the cylinder block upperpart in the engines. It is sealed tothe outside with the aid of an O-ring(2) and picks up the speed directlyat the integrated increment disc onthe 8th crankshaft web.

The function of the pulse pick-updoes not differ from that ofpreviously used pulse pick-ups. It isresponsible for sensing the speed ofthe crankshaft. The measurementfor the crankshaft pulse pick-up isbased on inductive principles. Thecrankshaft pulse pick-up transmits asignal to the engine control unitwhich calculates the crankshaftspeed.

4 9

Crankshaft pulse pickup outputvoltage varies with engine speed.Typical values range fromapproximately 500 millivolts atcranking speeds to 100 volts at highrpm, depending on the application.When measuring the output from amagnetic crank sensor, thevoltmeter should be set on anappropriate AC scale.

4 Cyl. Engine

The output from a crankshaft pulsepickup in a given engine will varybased upon the following:

• Cranking speed• Air gap of sensor to reluctor• Resistance of sensor windings• Temperature of sensor• Strength of magnet

The engine management systemsuse a crankshaft pulse pickup and areluctor that is part of thecrankshaft. The design of thecrankshaft reluctor is an importantconsideration when diagnosingthese systems. The crankshaftreluctors have seven notches thatgenerate the voltage signals sent tothe ignition module for everyrevolution of the crankshaft. Six ofthe notches are equally spaced at60-degree intervals around thecrankshaft. The seventh notch ispositioned 10 degrees from the sixthnotch. The signal from the seventh,or "SYNC," notch synchronises thecoil firing sequence with crankshaftposition

Crank shaft sensor signalIn the four cylinder engines theignition module is programmed torecognise the sync notch, countnotch number 1 and accept notch2 as the basis for the signal to firethe 2-3 cylinder pair. Next, themodule counts notches 3 and 4,then accepts the number 5 notchsignal as the basis for the signal tofire the 1 - 4 cylinder pair. Thenumber 6 and 7 notches are thencounted and the process beginsagain. Note that the coil pack forthe second cylinder in the firingorder always fires first during start-up.

5 0

Knock Sensor

The increases in pressure andtemperature caused by the pistoncan induce spontaneous ignition ofthe non-combusted fuel/air mixture.This sudden combustion can lead inturn to an extreme pressureincrease. This undesired combustionis termed "knocking".

The knock control system inconjunction with the fully electronicignition and fuel injection can bemanipulated by the engine controlunit to maintain the engine in aknock-free condition.

Principle:

The knock sensor is a piezo-electronic "microphone".

A piezo ring (3) is situated betweenan acceleration mass (1) and thesensor body (2).

When knocking occurs, the sonicpressure affects the accelerationmass.

This produces a voltage, which canbe measured by the sensorelectrodes (4) and further processedby the engine control unit.

30 Circuit symbol, knock sensor.

5 1

Injectors, Z 18 XE

The injection valves are fitted with 4-hole nozzles for the Z 18 XE, twojets for each intake valve. The four-jet valve with multi-hole metering isprovided with a nozzle hole disc (2calibrated bores). The holes arealigned in such a manner that thisproduces four injection jets.

Injection nozzles continue to beused with Z 18 XE that are stillprovided with an air containmentbut this is not used.

1 Current coil2 Needle3 Nozzle hole disc

4 Taper sleeve5 Valve seat6 Air duct intake manifold

5 2

Exhaust gas recirculation

This electronically controlledcomponent enables precise controlof the exhaust gas recirculation,which reduces emission of nitrogenoxides. The solenoid valve pintleposition is not dependent on thevacuum and can therefore can beopened or closed in all loadconditions. The quantity of exhaustgas is checked by the control unit.The control unit measures engineparameters such as speed, loadcondition and temperature via thesensor input signals and calculatesthe required exhaust gas quantity.

The exhaust gas recirculation valveconsists of the followingcomponents:

Solenoid valve:

The valve opening is dependent onthe coil current and is controlled bya pulse-width modulated (PWM)signal from the control unit. Theinternal coil spring forces the pintlein the default (closed) position.

Pintle position sensor:

This sensor provides feedback onthe actual pintle position. The pintleposition sensor is required for theexact position assessment of thesolenoid valve.

Exhaust gas re-circulation

L3312

Copyright by Adam Opel AG, Rüsselsheim,Germany.Reproduction or translation, in whole or inparts, is not permitted without the writtenauthorization of Adam Opel AG. All rightsunder the law of copyright are reserved byAdam Opel AG.

All data published in this brochurecorrespond to the indicated status and aresubject to change by Adam Opel AG.

For internal use only.

October 2001

Raytheon Training/Hughes International GmbHCityforum im EichsfeldFerdinand-Stuttmann-Strasse 15D-65428 Rüsselsheim, Germany