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21.1O4 EMISSION ONTROL YSTEMSYMPTOMDIAGNOSIS HARTS

2 Cranksnormally,but will not start (no combustion)Descrip-tion Cranks ormally,utnocombustionBatterys OKThroftle alve losedwhile rankinoOroubleshootingint)No uel njectiono enginebecauseof fuelshortage r no ignitionn all cylinders.o Nospark @ Low uel inepressure. lgnition ontrolmaltunction @ Lowengine ompressionressure. Malfunction f gnition ystemcomponent@ No uel iniection. Malfunction f fuelpump. Malfunction f iniectorStep Check Remedy1 Checkstrongbluesparkat eachsparkplugcorddisconnected. Yes Go to step5.No Go to nextstep.Check hat malfunctionndicator ight silluminated hile gnition witch s ON. Yes Malfunctionndicatoright s lluminated.Check or causes. Refer o TroubleshootingwithOBDII DiagnosticTtoubleMes.

3 Check gnition ystem.Check esistancef DLIcoils.Primary: pprox. .70OSecondary: 2- 13s}CheckwiringhamessbetweenECMand DLIcoil.

Yes Go 10nextstep.No Replacegnitionoilsor repairwiring amess.

4 Checkhigh ension ords.Resistance: 6k(YmCheck or damageo high ensionwire.Yes Go 1onextstep.No Replace igh ensionwire.

Connect hedala inkconneclorerminals UEL-PUMPandB+witha iumperwireand checkoperational oundof fuelpump.Yes Check hatengine tartson his condition:- Check uelpump elayor wiringhamess fengine tarts.

- Go o step7 if enginedoesnotslarl.No Go to nelitsteo.6 Check hatbattery oltage s appliedon c^/ wireof fuelpumpconnector hen gnition witch soN.Yes Checkcontinuityf tuelpump between/Yand B).No Check uelpump elay.Crankengine ndcheckoperational oundofiniector Yes Go to step10.No Go to nextsteo.I Check hatbattery oftage s appliedon injectorconnectorwhen gnition witch s ON. Go to nextsteo.No Checkwirebetweenmain elayand niector.9 Check hat he resistance f injectors 12Q. Yes Go to nextstep.No Replacenjector.

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EMISSION ONTROL YSTEM 21Step Check Remedy1 0 Connect he data inkconnectorerminalsFUELPUMPand B+ witha jumperwire and check uellinepressurewhile gnition witch s ON.Fuel ine pressure:4G41 psi (28+295kPa)

Yes Go o next tep.NO Whenpressure s low:Plug uelretumhoseand check uel inepressue.- Check uelpressureegulatorf pressincreasesbruptly.- Check logging etweenuelpumpanfuelpressureegulatorl pressureincreases lowly.- Checkmaximum ressure f fuelpumnotclogged.

Whenpressure s high:Check logging f fuel retumhose.- ll normal: eplaceuel pressureegula- lf notnormal: epairor replace.11 Checkenginecompressionressure.Enginecompressionpressure:163psi-270rPm

Yes Go o nextstep.No Check ngine ondition:- Wear f piston, iston ingandcylinde- Defect f cylinder eadgasket- Deformationf rylinderhead- lmproper alveclearance- Valve tuck o guide1 2 Checkcondition f all sparkplugs.. Sparkpluggap:0.032anchO.8mm). Excessive arbondeoosit. Contactwith high ension ord

Yes Go o nexlstep.No Cleanor replace.

1 3 Checkcrankshaft osition ensor. Yes Go o nextstep.No Check rankshattosition ensor ndrelatedwirehamess.1 4 ReplaceECM and check or properoperation.

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21-106 EMISSION ONTROL YSTEM3 Cranksnormally,qt won't start (partialcombustionlWhenengine is coldDescrip-tion Cranks ormally,utpartial, otcontinuous,ombustionccursBatterysOKFueloresentn ank

Oroubleshootingint)O Overrich irlfuel atio. Cloggedair cleaner lement. Matfunctionf massair lowsensor@ Overlean irfiuel atio. lncorrect uel njection ontrolcorrectionorenginecoolantemperature). Low uel linepressure. Air eakageat intake ystem

O Lowengine ompressionressure

Step Check Remedy'I Check hatmalfunctionndicatorioht silluminated. Yes Malfunctionndicatoright s illuminated.Check or causes.Refer to TroubEshootingwith OBD4 DiagnosticTroubleCodes.No Go o next teo.Disconnect parkplug.Crankengineand check park. Yes Go o next tep.No Replacegnition oil or repairwiring amess.

J Connect hedata inkconnectorerminals UELPUMPand B+ witha jumperwireandcheck uellinepressurewhile gnition witch sON.Fuel line pressure:40-41psi (285-295Pa)Yes Go to nelt step.No When pressure s low:Plug uel etumhoseand check uel inepressure.- Check uelpressure egulatorf pressureincreasesbruptly- Check logging etween uel pumpandfuelpressureegulatorf pressureincreases lowly- Checkmaximum ressure f fuelpump lnot clogged

Whenpressure s high:Checkcloggingl fuel retumhose.- It normal: eplaceuel pressure egulator- It notnormal: epairor replaceDoes njector peratewhilecranking ngine? Yes Go to nextstep.

No Check hat battery oltage s applied niniector onnector ndcheckwirebetweenrnain elayand njector.Check resistancef injector.Resistance:12Q Yes Go onext teo.NO Replaceniector.Checkcondition f IACvalve.

Open circuitbetweenACvalveandECMBattery vottage s applied o B/W wireof IACvaveIAC valvehoseconnection

Yes Go o nextstep.No Opencircuit r incorrect ollage:- RepairwiringhamessIncorrectACvalve esistance:- ReolaceACvalve7 Check erminal oltage f massair lowsensor,throttleposition ensor,gnition oils,enginecoolant emoeratureensor.Yes Go to nextstep.No Check or causes.

I Check contamination{sensorelementnsidemass air flowsensor- Yes ReolaceMAFsensor.No Go to nextstep.

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EMISSIONCONTROLSYSTEM 21Step Check Femedy9 Check hatengine tartswhenenginecoolanllemperatureensor onnectors disconnected. Yes Checkengine oolant emperalureens- lf normal: heckwiringhamess etwengine oolant emperatureensor nECM- It notnormal: eplace ngine oolantemDeralureensor.

No Go to nextstep.1 0 Check ir leakage t intake ystemcomponents. Yes Repairor replace.No Go o next tep.1 1 Checkenginecompressionressure.Enginecompressionptessure:163psi-270 pm

Yes Go to nextstep.No Checkengine ondition.- Wearofpiston,piston ingand cylinde- Delectof cylinder eadgasket- Deformation t cylinder head- lmproper alveclearance- Valve tuck o guideCheck ondilion l sparkplug.. Sparkpluggap:0.8 mm. Excessive arbon eoosit. Contactwith high ensionwire

Yes Go to nelitstep.No Cleanor reolace.

1 3 ReplaceECMandcheck orproperoperation.

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21-108 EMISSION ONTROL YSTEM4 Cranks, normally,but won't sl rt (partiatcombustion)- Afterengine s warmedupDescriF

IDN. Aflerengines etthotafterunning, rankingpeed. BatterysOK. Engine tarts ormally hen ngines cold

is OK

Oroubleshootingint)O Overrich irfiuel atio. Correctionor coolantemperalure. Fuel eakage t injectorVaoor ockoccurs. Fuelpressures notkeptwhenengine tops

(d

Step Check Remedy1 Warmup engine o normaloperatingemperatureand stop engine. onnect hedata ink connectorlerminalsFUELPUMPand B+ wilha iumperwiretor 3 minuteswhile gnition witchs ON. Thencheck hat enginestarts.

Yes Reolaceuelwithanother rand.

No Go o step3.Remove acuumhose rompressureegulatorand check hal engine tarts. Yes Check uelpressureegulalor.No Go o nextstep.3 Connecthe data inkconnectorerminalsFUELPUMPand B+ witha iumperwireand check uellinepressurewhile gnition witch s ON.Fuel ine pressule:40-41 psi (285-.295Pa)Yes Go o next teo.No When pressure s low:

Plug uel retumhoseandcheck uel ineDressure-- Checkuelpressureegulalorfpressureincreasesabruptly.- Checkclogging etweenuel pump ndfuel pressureegulator f pressureincreasesslowlv.- Check naximumressure f fuelpumpfnot clogged.When pressure s high:Checkclogging f fuel etumhose.- lf normal: eplaceuelpressure egulalor.- lf notnonnal: epair r replace.

Check hat uelpressures keptwhile gnitionswltch s OFF on the samecondition s step 2.Fuel ine pressure:19 psi min. or 5 minutesYes Go to slep6.No Go to nextsteo.

Plug uel pressureegulator utletandcheck hatfuelpressures keplwhile gnition witch s OFFFuel ine pressure:21 psi min. or 5 minutesYes Replace uelpressureegulator.No Check uelpumppressures kept.- lf nonnal: heck uel eakage rom niector- lf notnormal: eplaceuel pump

6 Check hat enginestartswhenenginecoolanttemperatureensorconnectors disconnected. Yes Checkengine oolantemperatureensor.- lf normal: heckwiringhamess etweenenginecoolant emperatureensor ndECM- lf not normal: eplace ngine oolanltemoeratureensorNo Goto nextstep.7 Check hat malfunctionndicatorioht silluminated. Yes Mal{unctionndicatoright s illuminated.Check or causes.Refer o Troubleshootinowith OBD4 Diagnostic roubleCoctes.

NO Go to nextstep.I Check erminal ohage l massair flowsensor,throttleposition ensor,gnition oils,enginecoolantemoeratureensor.Yes Go o next tep.No Check or causes.

9 ReplaceECM andcheck or properoperation.Revision1, 8/15/99

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EMISSION ONTROL YSTEM 2.IJ Cranks normally,but hard o start - AlwaysDescrip-tion . Cranks ormally,utcrankingimeup o startings excessivelyong. Batlerys OK. lttCllg4q lgqnq!while ngines idlingRefero"Roughtdting'ifnot ngooddting ondition)[f roubleshootingint)O Overrich irlfuel atio. lncorrectuel njection ontrol correctionorengine oolanl emperature). Low uel inepressure. Air eakage t intakesystem

Overrich irlfuel atio. Clogged ir cleaner lement. Maljunction f massair lowsensorSparkplugsnot ngoodconditionStep Check Remedy

1 Checkhatmaltunctionndicatoright silluminated hile gnition witch s ON. Yes Maltunctionndicatoright s illuminatedCheck or causes.Refer o Troubleshoowith OBDJI DiagnosticTroubteCodes.No Go o nextstep.2 Checkvacuum n intakemanifoldwhileenginesidling.Vacuum:more than 17.7 n.Hg(450mmHg)

Yes Go to neldsteo.No Checkair eakage t inlake ystem.

3 Check leanness f air cleaner lement. Yes Go o neldsteo.No Checkair ealGge t intake ystem.4 Check f enginestartseasilywhen hroftle alvequarter pen. Yes Checkcarbon eposit n throttle alveango to step6.

No Go o nextstep.5 Check uel inepressurewhileengine s idling.Fuel ine pressure:40-41 psi (28$295kPa). Yes Go to neldstep.No Whenpressure s low:Plug uel retumhoseandcheck uel inepressure.- Gheck logging etweenuel pumpanfuelpressureegulatorf pressureincreaseslowly.- Checkmaximum ressure f fuelpumnotclogged.6 Check etminal oltageof massair flowsenso(throttleposition ensor, gnition oil, enginecoolantemperatute ensor.

Yes Go o nextsteo.No Check or causes.

Connectuel pumpcheckconnector y umperwirewhile gnition witch s ON and check hatengine tartswhile uelpumpoperates.Yes Check uelpump elay.- lf normal, epair r replace iringham- lf notnormal, eplace elay.No Go o nexlstep.

o Check ontaminationf sensor nsidemassairflowsensor. Yes Cleanor replace-NO Go o nextstep.a Checkenginecompressionressure.Enginecompressionpressure:163psi-270 pm

Yes Go o next tep.No Checkengine ondition.- Wearof piston,pistondngandcylinderw- Defectof cylinder eadgasket- Deformationf cylinder ead- lmproper alveclearance- Valvestuck o guide1 0 Checksparkplugcondition.Spark luggap: 032 n (0.8mm)Excessive arbondeoositContactwith high ension ord

Yes Go o next tep.No Cleanor replace.

11 ReplaceECM andcheck or orooerooeration.Revision 1,8/1

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21-1'IO EMISSION ONTROL YSTEM6 Crankgnormally,bul hard to starl - When engine s coldDescrip-tion Cranksnormally, utcrankingime up to startings excessivelyongBattery s OKRestart s normalafterenginewarmedupEngine s normalwhileengines idling Befer o "Roughldling' f not n good dlingcondition)

Oroubleshootingint)O Overrich irlfuel atio @ EGRsolenoid alve. Mattunctiont massair flowsensor . Solenoid alvestuck. Ovedean irlfuel atio @ EGRcontrolvalve. Contaminatedir cleanerelement . EGRcontrolvave stuck. Malfunction f idlesoeedcontrol@ Overlean irlfuel atio. Malfunctionf iniection ontrol Conectionorengine oolant emperature)Step Check Remedy

1 Check hat malfunctionndicatoright silluminated hile gnition witch sON. Yes Malfunctionndicatoright s illumineted.Check or causes.Reter o Troubleshootinowith OBDI\ DiagnosticTroubteCodes.No Go o next steo.

Check erminal oltageol massair low sensor,throttleposilion ensor, gnition oils,enginecoolant emoeratureensor.Yes Goto nelit steo.No Checkor causes.

Check f enginestartseasilywhen hrottle alvequaner pen. Yes Checkcarirondeposit n throttlevalveandgo to step 6.No Go o neldsteo.

4 Checkvacuumn intakemanilold hileenaine sidling.Vacuum:more than 17.7 n.Hg 450mmHg)

Yes Go o nextsteo.No Checkair leakage t intakeair system@mDonenl.Checkcleanness f air cleaner lement. Yes Go o nexl steo.No Replace ir cleaner lement.Connecthe data ink connectorerminals UELPUMPand B+ witha iumperwireand check uellinepressurewhile gnition witchs ON.Fuel anepressure:4(Hl psi (28$295kPa)

Yes Go to next steD.No Whenpressure s low:Plug uel retumhoseand check uel inepressure.- Check uelpressureegulatorl pressureincreases bruplly.- Checkclogging etween uel pumpandluel pressureegulatorf pressureincreases lowly.- Checkmaximum ressure t fuelpump fnot clogged.Whenpressure s high:Checkclogging f fuel retum hose.- It normal: eplaceuelpressure egulator.- lf nol normal: epairor replace.

HeplaceECMand check or proper peEltion. Yes ReDlacehe ECM.No BeDlaceuelwithanother rand.

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EMISSION ONTROL YSTEM 217 Cranksnormally,but hard to start - After engine s warmedupDescrip-tion . Afterengine s left hotafter unning, ranksnormally,utcrankingime up to startings excessivelyo. Battery s OK. Startsnormallywhenengine s cold. Engines normalwhileengine s idling Refer o Rough dling tnot n good dlingcondition)

Oroubleshootingint)O Overrich irlluel atio. Malfunctionf uel ignition ontrol. Fuel eakagerom n,ectorO Vaoor ock. Fuel eakagerom inieclor

Step Check Remedy1 Checkhat malfunctionndicatoright silluminated hile gnition witch s ON. Yes Malfunctionndicatoright s lluminatedCheck or causes. Refer o Troubleshoowith OBD- Diagnostic TroubleCodes.

No Go o nenstep.2 Check erminal oltageoJmassair flowsensotthrottle osition ensor, gnilion oils,enginecoolant emperature ensor.Yes Go o nextsteo.No Check or causes.

Afterenginedlingand um gnition witchOFF.CheckhatJuel inepressures kept.Fuel ine pressure:more han 22 psi for 5minutes

Yes Go o neldsteo.No Plugotjtlet of fuel pressure egulator ndtignitionwitchOFF.Thencheckhat uelpressures kept.- lf nonnal: eplace uelpressureegula- lf notnormal: heck f tuelpumppresskept.tf uelpump s nornal, check uel eakagefrom niector.

4 Warmup engine o normal peratingemperature.^.1 .t^^ aa^i^6 a^^^^^t ih6 r{6t- li^l' a^^^.+^' Yes Replaceuel with another rand.terminals UELPUMPandB+ witha iumperwirelor 3 minuteswhile gnition witch s ON.Thencheck hatenginestartseasily.No Go o nextsteo-

5 ReplaceECMand check or properoperation. Yes ReDlacehe ECM.No ReDlaceuelwith another rand.

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21.112 EMISSION ONTROL YSTEMI Rough dling / Engine stops while idling - AlwaysDescription . Engine tartsnormally, utengine topsor vibraleswhile dling.

ffroubleshootingint)O Ovenich irlfuel atio. Air eakage. Malfunctionf fuel niection ontrol. Low uel ineoressure@ Clogging r malfunctionf one or more njectorsO Malfunctionf massair low sensor

@ Maltunctionf IAC valveO Malfunctionf sparkplug@ LowenginecompressionressureO Maltunctionl throttleposition ensoror relatedwnno namessStep Check Remedy

1 Checkhalmalfunctionndicatoright silluminaled hile gnition witch s ON. Yes Maltunctionndicatoright s illuminated.Check or causes.Refer o TroubleshootingwithOBD-ll DiagnosticTroubleCodes.No Go to nextsteD.Check erminal ottage l massair flowsensor,throtlleposition ensor,gnition oils,enginecoolantemperatureensor.

Yes Go o next teo.No Check or causes.

3 Checkoperating oundof injectorwhileengineidlino- Yes Go to step5.No Go 10nextstep.4 Check haiapprox.battery ottages appliedoninjector onnector hile gnition witch s ON. Yes Go to nextstep.No Check he wiringhamess etweenECMandiniector.5 Check he resistance f iniector.Resistance:12Ct Yes Go to nextstep.No Replacenjector.Check hatvoltageof throttleposition ensorterminalY/Bwire) s 0.3{.7V anddoesnot vary. Yes Go to nextstep.No Replace hrottleposition ensoror wiringhamess.

Check f sensorelement nsidemassair flowsensors contaminated.

Yes Cleanor reolace.No Go o next teo.I Checkengine ompression ressure.

Enginecompressionpressure:163psi - 270 rpmYes Go o nexsteo.No Checkenginecondition.- Wearof piston,piston ing and cylinderwall- Defectof cylinder eadgasket- Deformationl cylinder ead- Valve tuck o guide

9 EeplqcgECMand check or properoperation.

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EMISSION ONTROL YSTEM 219 Rough dling/ Enginestgps whileengine s idling - Engine coldDescrip-taon . Engine peed sslow, ngine topsor vibrateswhilewarmingup engine.

Oroubleshootingint)O Insufficientntakeair.. Malfunction{ massair lowsensor. Clogged ir cleanerelement. Malfunctionf IACvalve@ Malfunctionf fuel niectionontrol.. Malfunctionf fuel njectionontrol evices(conectionor enginecoolantemperature)Step Check Remedy1 Checkhat mallunctionndicatoright sillum'nated hile gnition witch s ON. Yes Maltunctionndicatoright s illuminatedCheck or causes.Refer o Troubleshoowith OBD-tl DiagnosticTroubleCodes.

No Go to nextslep.Check ir eakage t ntake ystemand vacuumof dynamic hamberwhileengines idling.Vacuum:17.7 n.Hg 450mmHg)

Yes Go o next tep.No Checkair leakage t intakesystem

@mDonent.Check leanness fair cleaner lement. Yes Go to nextsteo.No Replace ir cleaner lement.4 Checkerminal ottage t massair flowsenso(throttle osition ensor,gnition oils,enginecoolantemperatureensor.Yes Go to nextslep.No Check or causes.

5 Check esistance t engine oolant emperaturesensor.. At -4"F(-20'C)resistancehouldbe 14.6 o17.8kA. At68F(20"C) esistancehouldbe2.2 to 2.7 (f). At 176"F 80"C) esistancehouldbe 0.29 o0.35kf)

Yes Go to neldstep.

No Replace he engine oolantemperaluresensor.Replace CMandcheckor properoperation. Yes Replacehe ECM.No Replace uelwithanother rand.

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21-114 EMISSION ONTROL YSTEM10 Rough idling / Enginestops while engine s idlinq - After engine s warmed upDescription . Engineoperations normalwhilewarmingup engine, ut enginestopsor vibrates tterwarming p.

Oroubleshootingint)O Malfunctionl IAC valveO Overlean ir/fuel atio. Air leakage. Low uel ineoressureO Malfunctionl ignition ystem

@ Overrichairlfuel atio. Malfunction f fuel njectionontrol(conectionor coolantemperature)Lowenginecompressionressure

Step Check Remedy'I Check hat malfunctionndicatoright silluminaledwhile onition witch s ON. Yes Matfunctionndicatoright s illuminated.Check or causes.Reter o TroubleshootingwithOBDI! DiagnosticTroubleCodes.No Go to nextsteD.2 Check erminal oltageof massair flowsensor,throttleposition ensor, gnition oils,enginecoolant emoeralure ensor.Yes Go o next leo.No Check or causes.

Checkvacuumof intakemanifold.Vacuum:more than 17.7 n,Hg 450 mmHg)

Yes Go o next tep.No Check or air leakageat intakes)6temcorDonent.

4 Checkcleanliness f air cleaner lement. Yes Go to nexlsteo.No Replace ir cleaner.c Check uel linepressurewhileengine s idling.

Fuel ine pnessure:40-41psi (2&t295 kPa)(whendisconnectingacuum ose rompressureregulator)

Yes Go to nextstep.No Whenpressure s low:Plug uel retumhoseand check uel ineoressure.- Checkuel pressureegulatorf pressureincreases bruptly.- Checkclogging etweenuel pumpandluel pressureegulatort pressureincreases lowly.- Checkmaximum ressure t fuelpump lnot clogged.

6 Disconnect nginecoolantemperalure ensorconnector nd check hat engine onditionimDroves.Yes Replace he engine oolantemperaturesensor.No Go to nextsteo.

7 Checkoperating oundol injeclorwhileengine s Yes Go o step10.rdlrng. NO Go to next steD.8 Check esistance l injectorResastance: 2fl Yes Go o nelitsteD.No Replace njector.9 Checkengine@mpression ressure.

Engine compressionpressure:163 psi - 270 rpmYes Go o nextstep.No Check he engine.

1 0 ReplaceECMandcheck orproperoperation.

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EMISSION ONTROL YSTEM 211 1 Bough idling Enginestops while engine s idling - WhenA"/Cs in operationDescrip-lion Engine topsor vibrates xcessively henA,/Cs operatingldlingcondilions normalwhenA/C s turnedOFF

[froubleshootingint)O Malfunction f IACcontrolsystem O MalfunctionfA,/C perationalwitchStep Check Remedy1 Check hat malfunctionndicatoright silluminated hile gnition witch s ON. Yes Malfunctionndicatoright s illuminated.Checkor causes.Refer o Troubleshoowith OBDI| DiagnosticTroubleCodes.

No Go o nen step.Checkair conditionerut relay s ON/OFFwhenair conditionerwitch sON/OFF. Yes Goto nextstep.No Malfunctionf air conditionerwitchor airconditionerut relay.ls therecontinuity etween in No.64 and 65olECM? Yes Repairhewiring amess.No Go o nextstep.

4 ReplaceECMand check orproperoperalion.

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EMISSION ONTROLSYSTEM 2113 High dle speedafter engine warmedupDescrip-Iron . Excessively igh dlespeedafterenginewarmedup

Oroubleshootingint)Excessiventakeair flowO Throttle alvenot closed ompletelyO Malfunction f idlespeedcontrol. IACvalvestuck

IACvalveconnector isconnecledIncorreclnpulsignal romcoolanttemDeratureensorStep Check Remedy1 Check hat hrottle alve s closed omoletelvwhenacceleratoredals released. Yes Go o nextstep.No Check orrect nstallation nd reeoperof throttle inkage. f not normal, leanoradjust inkage.

Check hat rnalfunctionndicatoright silluminated hile gnition witch s ON. Yes Maltunctionndicalor ight s illuminatedCheck or causes. Referlo TroubleshoowithOBDI| Diagnostic TroubleCodes.No Go onext tep.

Disconnectngine oolanlemperatureensorconnector ndcheck hatengine onditionrmDroves. Yes Replace nginecoolanlemperatureenNo Go o nelitstep.4 PlugPCV hoseconnectedo the ntake nanifoldand checkengine peeddecrease. Yes Checkor replace he PCVvalve.No Go o nextstep.Check hai voltage f throttle osition ensorlerminal Y/Bwire) s 0.3-0.7V nddoesnotvary. Yes Replacehrottleposition ensor r wirinhamess.

No Go o ne),tstep.6 CheckECM erminal oltage. Yes Go o nelt slep.No Check or causes.ReplaceECMandcheck orproper peration.

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21-118 EMISSION ONTROLSYSTEM1 4 Variationof idle gpeed ldle huntingDescription . Periodic nginespeed ncrease nddecreasewhileengine s idling

ffroubleshootingint)O Malfunction1 hrottleposition ensorsystem@ Air eakage@ Malfunctionf IACcontrolsvstem@G\

Fuel njections irregularMalfunctionf ignition yslemStep Check Remedy1 Check hatmalfunctionndicatoright silluminated hile gnition wilch s ON. Yes Malfunctionndicatoright s illuminated.Checkfor causes.Refer o TroubleshootinowithOBD4 DiagnosticTtoubteCodes.

No Go o next tep.Check hatvoltageof throttleposition ensorterminal Y/Bwire) s 0.3{.7V and doesnot vary. Yes Go o neritsteo.No Replace hrottleposition ensorotiiviringhamess.Checkair cleanerelement. Yes Go o next tep.

NO Replace ircleaner lement.4 Disconnect igh ensionwireand checkequalenginespeeddecrease n all rylinders. Yes Go o next tep.No Go to step7.CheckECM erminalvoltage. Yes Go to nextsteo.No Check or causes.o Checkmassair flow sensor.(Page 1-129)- Yes Go o step12 .No Replace he massair flowsensor-Checkoperating oundof injectorwhileengine sidlino. Yes Go to step9-No Go o next teo.8 Check hal approx.battery oltagesappliedoniniector onnectorwire. Yes Go o next tep.NO Check he wiringhamessbetweenECMandiniector.9 Check esistance f injector.Resistance:12C! Yes Go to nextstep.No Replace niector.1 0 Checksparkplugs or properoperation. Yes Go o next tep.No Cleanor replace.'fi Checkengine ompression ressure.Engin cornpressionpressute:16:lpsi - 270 rpm

Yes Go to nexl step.No Check orcause.

1 1 Check or fuel eakagerom niector. Yes Reolacehe niector.No Go o next tep.1 2 ReplaceECMand check or proper peration.

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EMISSION ONTROL YSTEM 211 5 EnEinestalls on decelerationDescrip-tion Engine topsunexpectedlyuringor afterdecelerationldling onditions normal

Oroubleshootingint)Engine peeddecreases bruptlywhen acceleratoredal s released, hichcan causeconneclorso come ooO Maffunctionf idleair control O Malfunction f fuelcut controlO Malfunction f throttle osition ensorsvslemStep Check Remedy1 Check hat malJunctionndicator ight silluminaled hile gnition witch s ON. Yes Malfunctionndicatorighl s illuminatedCheck or causes.Refero TroubleshowithOBD-tlDiagnosticTroubleCodes.

No Go to nelitstep-2 Check hrottle osition ensor, ACvalve erminalvoltageand relatedwiringhamess. Yes Go to nextslep.No Repair he wiringhamess r checkunitp3 CheckECM erminalottagesorC211-2, 211-29, C211-59, 211-71 ndC211-73. Page21-17\.Yes Go to neldsteo.No Check or cause and rcoair.

4 Checkcontact ondition f the followingconneclors:- Throttleposition ensor,massair low sensor,ignition oils, niector, rankshaft ositionsensor,uelpump elay,ECM.

Yes Goto nextstep.No Repairor replace.

ReplaceECMand check or properoperation.

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21-120 EMISSIONCONTROLSYSTEM16 Enginestalls suddenly(lntemittent),sudden enginestopDescrip-tion Engine topssuddenlyand ntermittenllyEngine s normaluntil engine tops

Cfroubleshootingint)O Malfunction f IACcontrolsystem@ Malfunction f throttle osition ensorsystem o Intermittentlyoosened onlactol electricalwirinoharnessStep Check Remedy

'I Check hat malfunctionndicatoright silluminaled hile gnition witch s ON. Yes Malfunctionndicatoright s illuminated.Check or causes.Reler to TtoubleshootinowithOBDI\ DiagnosticTroubteCodes.No Go to nextstep.Checkcontact ondition l the followingconnectoIs:- Throttleposition ensor,massair lowsensor,ignilion oils, niector, rankshaft ositionsensor, uelpumprelay,ECM.

Yes Repairor replace.No Go onext tep.

Measure rankshatt osition ensorand massairflowsensorsignalsand checkhat normal ignalsare detecled.

Yes Go o next tep.No Repair r replace.CheckECM erminal oltagesorC211-16, 211-41 ,C211-43, 211-59, 211-71ndC211 73 .(Page 1-17).

Yes Go o nexstep.No Check or causesand repair.

5 ReplaceECMand check orproperoperation.

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EMISSION ONTROLSYSTEM 211 7 Stumble Hesitationon accelerationDescrip-ton . Vehicle eemso stop or a time mmediatelyfterpressing cceleratorr rattlesa littleduringacceleralion

(Troubleshootingint)O Leanairlfuel ationon acceleralion. Low uel ineoressure Air leakageMalfunctionf fuel injection ontrolStep Check Remedy1 Check hat malfunctionndicatoright silluminated hile gnition witch s ON. Yes Mallunctionndicators illuminated. hefor causes.Reler to Troubleshooting itOBD-ll DiagnosticTroubleCodes.

No Go to nextstep.Checkvacuum n ntakemaniloldwhileenoineidling.Vacuum:more han 17.7 n.Hg(450mmHg)

Yes Go o nextstep.No Checkair eakage l air ntake ystem nreparr.

Checkcleanlinessf air cleanerelement. Yes Go to nextstep.No Replace ir cleaner lement.4 Checkmassair lowsensor.- Intemal esistance,ottage, ontaminationfsensorelement tc.

Yes Go to nextstep.No Reolacehe massair flow sensor-

3 Checkengine oolanlemperatureensor. Yes Go to nextstep.No Replacehe enginecoolanl emperatursensor.6 Check hrottlepositionensor.

Voltage between erminals:ldling condition: V maximumThrottle valve ull opn: about 4V

Yes Go to nextstep.No Beplache hrottleposition ensor.

Disconnectnjector@nnector ne byonewhileengine s idling, ndcheckequalengine peeddecreaseor eachcylinder.Yes Go to nextstep.No Check nlector.Reter lo Fuel Svs'tem,Section 2.

8 Checkconect nstallationnd free oDerationlthrottle inkage. Yes Go o nextstep-No Adjustor replaceoint or damagedinkaand adiusldeflection f throttle able.9 Check uel linepressure hileengine s idling. Yes Go to nelitstep.

No Whenpressure s low:Plug uel retumhoseand check uel ineDressure- Check uelpressure egulatori pressincreasesbruptly.- Check logging etweenuelpumpanfuelpressureegulatorf pressureincreaseslowly.- Checkmaximum ressure fJuelpumnotclogged.1 0 Checkair passage ndvacuumhose nstallation. Yes Go to nextstep.

No Repair.1 1 Checkexhaust ystem logging. Yes Repair r replace.

No Go to nextstep.' t2 ReplaceECMandcheckor properoperation.

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21-122 EMISSION ONTROL YSTEMt 8 Surging while cruisingDescrip-tron . Repeatedngine peedvarialion ccurs t all times

ffroubleshootingint)O Malfunction f throttle osilion ensorsystemO Misfire O L@ Looseconlactof wiringhamesseanairlfuel atioStep Check Remedy

,1 Check hatmaliunc"tionndicatoright silluminated hile gnition wilch s ON. Yes Malfunctionndicatorighl s illuminated.Check or causes.Refer o TtoubleshootinowithOBDI\ DiagnosticTroubteCodes.No Go to nextstep.Checkvacuumn intakemanifoldwhileenoineidling. Yes Go o next tep.No Checkair eakageat air intake yslemandrepair.

.t Check hrottle osition ensorVoltagebetween termanals:ldling condition: V maximumThrottlevalve ull open: approx.4VYes Go o next tep.No Rephce he throttlepositionsensor.

Disconnectrontheatedorygensensor onneclorandcheck orproperopetion. Yes Replacehe rontheatedoxygen ensor.No Go to nextsteo.5 Check hatvehicle peedsensorsignal nput oECM s normal.- ECM erminalNo.42

Yes Go o nextstep.No Repair he wiringhamessor vehicle peedsensor.o Check ECMerminal oltagesor C211-42, 211-59, C211-71ndC211-73page 1-17). Yes Go o next tep.No Check orcausesand reoair.7 Checkcorrectnstallationnd reeoDeralion fthrottle inkage. Yes Go o next teD.No Adiustor replaceointor darnagedinkageand adiusldetlection f throttlebodycable.I Checkcleanlinesst air cleanerelement. Yes Replace ir cleanerelement dry ype).No Go o nextstep.Check uel inepressurewhileengines idling.

Fuel linepressure:4041 psi (28$295kPa)Yes Go o next teo.No Whenpressure s low:Plug uel retumhoseand check uel inepressure.- Check uel pressure egulalorf pressureincreasesbruptly.- Checkclogging etween uelpumpandluelpressureegulatorf pressureincreaseslowly.- Checkmaximum ressure f uelpump fnotclogged.

1 0 Checkexhaust ystem logging. Yes Repair.No Go to nextstep.

1 1 | ReplaceECMand check or properoperation.

Revision1 8/'15/99

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20/21

EMISSIONCONTROLSYSTEM 211 9 Lack of powerDescrip-tDn . Lackof powerat ull hrottle. Lowermaximum ehicle oeed. ldlingspeed s normal

Oroubleshootingint)O Insufficientntakeair. Throttle alvedoesnot open ully. Cloggedntakeair systemO Leanairlfuel atio. Fuel inepressuredecrease-. Malfunctionf fuel niection.

@ Malfunctionf ignitionLow enginecompressionressure

Step Check RemedyCheck he tollowingtems.- Clutchslippage- Brakedragging- Lackof tire air oressure- lmproperire size

Yes Go to nextstep i normal.

No Repair.ls throftle alve open ullywhendepressingacceleratoredal ully? Yes Go o step 5.No Goto nextstep.CheckEGR control alveoperationwhile engineis dling. Yes Go to nexlstep.No Check he EGRsolenoid ave.

4 Check orrect nstallation{ hrottle able. Yes Go to nelitstep.No Repair r adjusthrottle able.Checkcorrectoperation f throttlebody. Yes Go to nelt slep.No Repairor replacehrottlebody.6 Check hat maltunclionndicatoright silluminated hile gnition witch s ON. Yes Malfunctionndicatoright s illuminatedCheck or causes.Refer o Troubleshoowith OBDI! DiagnosticTroubleCodes.No Goto nextstep.

7 Check he camshaftDositionensor. Yes Go to nextstep.No Checkcamshaft osilion ensor ndrelawire hamess.Check hrottlepositionensor.Vottagebetween terminals:ldling condition: lV maximumThrottle valve full open:approx. 4V

Yes Go o nextstep.No Replacehe hrottle osition ensor.

I Check acuum n intakemanifoldwhile enoine sidling.Vacuum:more han17.7 n.Hg 45OmmHg)

Yes Go o nextstep.No Repair ntake ystem nddynamic ham

1 0 Disconnectnlector onnector ne by one whileengine s idling,andcheckequalenginespeeddecreaseor eachcylinder. Yes Go o next tep.No Check niector.Rele( o Fuel Syitem,section 2.Check leanliness f air cleaner lement. Yes Go to nextstep.No Reolace ircleaner lement.

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21-124 EM]SSION ONTROLSYSTEMStep Check Remedy

t z Keep engine dlingand um ignition witchOFF.Check hat fuel inepressures kept.Fuel line pressure:more than 21 psi for 5minutes

Yes Go o nextstep-No Plugoutlet f pressureegulator nd urnignition witchOFF.Then check hat uel inepressures kept.- lf normal: eplace ressure egulator.- lf nol normal: heck uel pumppressure

kept.lf fuelpump s normal, heck uel eakagefrom niector.

Does uel ine oressure ncreasewhenaccelerating bruptly?Fuel line pressure:40-41 psi (285-295 Pa)Yes Go o next tep.No Checkuel ineand uel ilter cloggingndreoairf notnormal.

1 4 Checkmassair tlow sensor.- lntemal esistance,ontaminationf sensorelement,elc.- Measureoutputvoltage. 1.5Vwhen dling. 5V whenopen ully

Yes Go o nelitslep.No Reolacemassair Jlow ensor.

1 q Check gnition ystem.- Check esistance l DLI coilPrimary:Approx.0.70frSecondary: 2- 13O- Check wiring hamessbetweenDLI coil and ECM

Yes Go o nextstep.No Replacegnition ollsor repairwiringhamess.

t o Checkhigh ensionwires. Yes Go o nextstep.No Replace igh ensionwires.1 7 Checksparkplug. Yes Go o nelitstep.No Cleanor reolace.

1 8 Checkenginecompressionressure.Engine compressionpressure:153psi - 270rPm

Yes Go o nerl slep.No Check ngine ondition.- Wearol pislon,piston ing and cylinderwall- Defect t cylinder eadgasket- Deformationf cylinderhead- lmproper alveclearance- Valveguide tuck1 9 ReplaceECMand check or proper peration. Yes ReDlacehe ECM-

No ReDlaceuelwithanotherbrand