
PGM-FI System
Fuel Supply System
D017-il Th""""ntool indicates Diagnostic Troubte Code {DTC) p0171;Thefuet system istoo lean.
1P0172 | fne scan tool indicates Dlagnostic Trouble Code (DTC) P0172:Thefuel system istoo rich.
Description
By monitoring the Long Term Fuel Trim, long term malfunctions in the fuel system will be detected.lf a malfunction has been detected during two consecutive trips, the MIL will come on and DTC P0171 and/or P0172 will bestored.
NOTE: lf some of the DTCS listed below are stored at the same time as DTC P0171 andlot P0172, ltouhleshoot those DTCSfirst. then recheck for DTC P0l7l andlot P0172.
P0106-8, P1128*3. *5, P1129*3 *5 MAP Sensor
P0135; Primary HO2S Heater
P0137. P0138: Secondary HO2S
P0'141: Secondary HO2S Heater
P0401: EGR Flow Insufficient*1
P0441: EVAP System Insufficient Purge Flow*6
P1259: VTEC System*,
P1491:EGR Valve Lift Insufficient*r
P1498: EGR Valve Lift Sensor Hjgh Voltage*r
*r: D16Y5 engines*' : Dl6Y5, D16Y8, 81642 engine*3: '97 models*a:'96 modelsf 5: '98 - 00 models*6: '96 D16Y5 engine,'96 D16Y7 engine,'96 D16Y8 engine (sedan),'97 D16y5 engine,,97 D16y7 engine (coupe: KA, KC mo+els, sedan KA. KC, KL (DX) models. hatchback; all models),'97 D16Y8 engine (sedan: KA, KC models)
Possible Cause
DTC P0'171
loo lean
DTC P0172
too rach
Fuel Pump insuff icient f lovpressure
Fuel Feed Line clogged, leaking
Fuel Pressure Regulator stuck open
Fuel Filter clogged
Fuel Injector clogged, air inclusion
Gasoline doesn't meet Owner's Manual spec.
Primary HO2S (Sensor 1) deteriorated
MAP Sensor range/performance*.
EGR System malfunction (too much flow)*1
Valve Clearance
Exhaust leak
Fuel Pressure Regulator clogged, stuck closed
Fuel Return Pipe clogged
Fuel Injector leaking
Gasoline doesn't meet Owner's Manual spec.Primary HO2S (Sensor 1) deteriorated
MAP Sensor range/performance*a
EGR System insufficient flow*1
EVAP Purge Control Solenoid Valve leaking, stuck opened
Valve Clearance
11-164

PGM-FI System
Random Misfire
lFoioo l*u o, [FTioo l*' *' and
The scan tool indicates Diagnostic Trouble Code (DTC)
P0300*5 or P1300*3 *1 and some of P0301 - P0304:Random misfire.Description
Misfire detection is accomplished by monitoring the crankshaft speed with the crankshaft speed fluctuation (CKF) sensorwhich is attached to the crankshaft.
lf misfiring strong enough to damage the catalyst is detected. the MIL will blink during the time of its occurrence, and DTCP0300*5 or P1300*3'*' and some of DTCs P0301 through P0304 will be stored. Then, after misfire has ceased, the MIL willcome on.
lf misfiring that increases emissions is detected during two consecutive driving cycles, the MIL will come on, and DTCP0300*5 or P1300*3 *a and some of DTCS P0301 through P0304 will be stored.NOTE: lf some of the DTCS listed below are stored at the same time as a misfire DTC. troubleshoot those DTCS first, thenrecheck for the misfire DTC.
P0106*4. P0107. P0108, P1128*3 *5, Pl129*3 *5; MAP sensorP0131. P0132: HO2S
P0171, P0112i Fuel metering
P0401, P 1491, P1498: EGR svstem*1P0505: ldle Control SystemP1253: VTEC System*,P1361, P1362: TDC sensorP1381, Pl382: CYP sensorP1508: IAC valve
Possible Cause. Fuel pump insufficient fuel pressure, amount of flow. Fuel line clogging, blockage, leakage. Fuel filter clogging. Fuel pressure regulator stuck open. EGR system malfunction*1. Distributormalfunction. lgnition coil wire open. leakage *l: D16Y5 engine. lgnition control module malfunction *2: D16Y5, D16Y8, Bt6A2 engine. MAP sensor range/performance, poor response*r *3: '97 models. Valves carbon deposit *4;'96 models. Compression low *5: '98 - 00 models. IAC valve malfunctionr.. VTEC system malfunction*,. Fuel does not meet Owner's Manual spec., lackoffuel. HO2S. HO2S circuit
Troubleshooting
By test-driving, determine the conditions during which misfire occurs, Depending on these conditions, test in the orderdescribed in the table below.
Possible
- --^ ---
rage
causeEGR*1
system
Crankshaft
position (CKP)
sensor
Fuel
pressure
Distributor and
lgnition wirestcMClearance
tAc
ValveMAP
sensor
section 611-230,
231section 23section 23section 611-19411
Only low rpm and
loado@@oo
Only accelerating@o@@
Only high rpm and
toaooo@
Not specificoo@
NOTE: lf misfire doesn't recur, some possible causes are fuel that doesn't meet owne/s manualspec, lack of fuel, carbon deposits on spark plug, etc.
1 1-1 66
I
P0304

I
Misfire Detected in One Cylinder
P0301 | The scan tool indicates Diagnostic Trouble Code (DTC) P0301: Cylinder 1 misfire detected.
[F03O2l 16"""untool indicates Diagnostic Trouble code (DTc) P0302: Cylinder2 misfire detected.
[FO3Ofl 16" ".un toot indicates Diagnostic Troubte Code (DTC) P0303; Cylinder 3 misfire detected.
I P0304 I ths..rr tool indicates Diagnostic Trouble Code (DTC) PO3O4: Cylinder 4 misfire detected.
D€scription
lMisfire detection is accomplished by monitoring the crankshaft speed with the crankshaft speed fluctuation (CKF) sensor
which is attached to the crankshaft,
lf misfiring strong enough to damage the catalyst is detected, the MIL will blink during the time of its occurrence, and DTC
PO3O1, P0302, PO3O3 or P0304 will be stored. Then, after the misfire has ceased, the MIL will come on.
lf misfiring that increases emissions is detected during two consecutive driving cyclss, the MIL will come on, and DTC
P0301, P0302, P0303 or P0304 will be stored.
NOTE: lf some of the DTCS listed below are stored at the same time as a misfire DTC, troubleshoot those DTCS first, then
recheck for the misfire DTC.
PO106*1, P0107, P0108. P1128*3'*5, P1129*3'*5: MAP sensor
P0131, P0132: HO2S
P0171, P0172iFuel suppiy system
P0335, P0336: CKF sensor
P0401. P1491, P1498: EGR system
P0441: EVAP system Insufficient purge flow*6
Pl359. P1361. Pl362: TDC sensor
P1381. Pl382: CYP sensor*o: '96 models*6: '96 D16Y5 engine,'96 D16Y/ engine,'96 D16Y8 engine {sedan),'97 D16Y5 engine,'97 D16\4, engine (coupe: KA,
KC models, sedan KA. KC, KL (DX) models, hatchback:all models),'97 D16Y8 engine (sedan: KA, KC models)
Possible Cause
. Fuel injector clogging, fuel leakage, air leakage
. Fuel injector circuit open or shorted
. Spark plug carbon deposits, fouling, malfunction
. lgnition wires open. leaking
. Distributor malfunction
. ComDression low
. Valve clearance out of spec
. VTEC system malfunction (D16Y5, D16Y8. 81642 engine)
. HO2S
. HO2S circuit
(cont'd)
11-167
r'a

PGM-FI System
Misfire in Detected One Gylinder (cont'dl
Troubleshootin g Flowchart
NOTE:. lf there is no treeze data of misfiring,just clear the DTC.. It there is no freeze data of misfiring,test drives under various conditions
- The MIL has been reoorted on.- DTC P0301. P0302. P0303, orP030il is indicated.
Check the fuel iniecto. lunction:Stan the engine, and listen for aclicking sound at the fuel injectorin the problem cylinder.
Check for an open or short in theharness between ECM/PCM andthe fuel iniector.
Repair open or short in the wir€.
Replace the fuel iniector.Sub3titute a known-goodECM/PCM and recheck. Itsymptom/indication goesaway, replace the original ECM/PCM.
Problem verification:1. After checking and recordingthe freeze data, do the ECM/PCM Reset Procedure.2. Exchange the spark plug fromthe problem cylinder with onefrom another cylinder,3. Connect the SCS service con'nector,4. Test-drive the vehicle severaltimes in the range ofthe free2edata.
(To page 11-169)
1 1-1 68

I
ll
t
NOTE: lf there is no freeze data of mis_
firing, test drives under various condi
tions are necessary.
(From page 11'168)
Intermittent misfire due to sparkplug fouling, etc. (firing is OK arthis time).
ls DTC P0301, P0302, P0303,or P0304 indicated?
Does the misfire occur in theother cylinder?Replace the faulty spark plug.
Check for fuel iniector mallunc-
l|on:1. Exchange the fLrel injectorfrom the problem cylinderwith one from another cylinder.2. Let the engine idle for trrvo min-
utes.3. Test-drive the vehicle severaltimes in the range ot the freeze
data.
lntermitt€nt mistire due to badcontact in the fuel iniector con-nector (firing is OK at this time).
ls DTC P0301, P0302, P0303,or P0304 indicated?
Does the mistire occur in theother cylinder?Replace the taulty fuel injector.
Check lhe following items:. Cylinder leak-down. Compression. Crankshatt speod tluctuation
{CKF) sensoi
1 1-1 69

Elestrical Load Detector (ELD) f96 - 98 Models''99 - 00 D16Y5 engine with M/T)
ThescantoolindicatesDiagnosticTroubleCode(DTC)P1298:AhighvoltageproblemintheElectricalLoad
Detector (ELD) circuit
ELD 3P CONNECTOR {G's'I
Wire side ol female terminals
EL IGFN/REDI
Problom vcrificttion:
1. Do the EcM/PClVl Reset Pro-
cedure,2. Start the engine.
3. Turn on headlights.lntarmitt..rt l.ilur., ryttcm b OK
.t thia tim. Ch.ck lor Poo' con-
nections or looaa wir.3 at C131
lbcd.d und.r right ide ol dalhl'
Gl5a {EU)} .nd ECM/PCIYI
ls DTC P1298 indicated)
Ch.ck lor tn oPan in tho wir'
(lGl linol:1. Turn the ignition and head'
liohts OFF2. D]""onn""t the ELD 3P con_
nector-3. Turn the ignition switch ON {ll)'
4. Measure voltage between body
ground and the ELD 3P connec
tor terminal No. '1.
R.oair ogan in tha wira Mw"n
ru". rs ltTEnrlton SP SelSOn
t?.5 A, fu!. in th. undcr-dr3h
tu3e/r.l!Y box .nd ELD.
Chcck lor tn oP.h in thc wire
{GND lincl:1. Turn the ignition switch and
headlights OFF.
2. Disconnect the ELD 3P con_
nector'3. Check for continuity between
body ground and the ELD 3P
connecto. terminal No 2
Raprir opcn in the wira bstwt€n
ELD conncctor lnd G/O2.
Ch.ck lor !n oplo in tha wirc IEL
lin.l:Check for continuity between the
ELD 3P connector terminal No 3
and ECM/PCM connector termi
nal D'16.
Rapaii opcn in the wira b€tw"n
ECM/FCM (I)161 .nd th. ELD'
Ch.d( fo. r m.llunction in thc ELD:
1. Reconnect the ELD 3P con'
2. Start th€ engine and allow it
to idle.3. Wh ile measuring voltage
beNveen ECM/PCM connector
terminals D16 and A9, turn
the headlights on {low).
Does the voltage droP?
Sub3titut. . known_good ECM/
PCM .nd rcch.ct. lt sYmptom/
indication goas away/ iapllc'
thc origin.l ECM/PCM
wire side of lemale termrnals
Wire side of Iemale terminals
t'a
)
1 1-181

PGM-FI System
Elestrical Load Detector (ELDI ('99 - 00 Models except D16y5 engine with M/Tl
The scan tool indicates Diagnostic Trouble code (DTCI Pl298: A high vottage problem in the Etectrical LoadDetector (ELD) circuit.
ELD 3P CONNECTOR (65/0
EL {GRN/REOI
Wire side of fernale terminals
ELD 3P CONNECTOR (CA54I
TIr l2l3l
I crvo
(o) (BrKr
Y
Wire side of lemale terminals
ECM/PCM CONNECTORSA (32P1
Wire side of lemaleEI- IGRN/RED)terminals
ECM/PCM CONNECTORS
A {32P)
Problem ve.itication:1. Do the ECN4/PCM Reset pro
cedure.2. Start the engine.3- Turn on headiights.Inte.mittent teilu.e, svstem is OKat this lime. Chock for Door con-nections or loose wires at Ci31{located under Jight side otdaihl, C354 (ELD) and ECM/PCM.
ls DTC P1298 indicated?
Check for an open in the wire{lG1 line}:1. Turn the ignition and head-lights OFF.2. Disconnect the ELD 3P con
3. Turn the ignition switch ON (ll).4. Measure voltage between bodyground and the ELD 3P connec-torterminalNo. 1.
Repair opon in tho wiro batwe€nNo. 15 ALTERNATOR Sp SENSOR{7.5 A} fuse in th6 undor-dashIuse/reley box and ELD.
ls there battery voltage?
Check for an open in the wiro{GND linel:1. Turn the ignition switch andheadlights OFF.2. Disconnect the ELD 3P connector.3. Check for continuity betweenbody ground and the ELD 3Pconnector terminal No. 2,
Repair open in the wire bstwoenELD connsctor and Gia02.
Check ,or an open in the wire IELlinel:1. Disconnect the ECM/PCM con-nector A (32P).2. Check for continuity betweenthe ELD 3P connector terminalNo. 3 and ECM/PCM connec-tor terminal A30.
Chock fo. a malfunction in the ELD:'1. Reconnect the ELD connectorand ECM/PCM connectorA (32P).
2. Stan the engine and allow itto idle.3. While measuring voltagebetween ECM/PCM connectorterminals A30 and B2O, turnthe headlighrs on ow).
ls there continuity?
Repsir op€n in the wire betweenELD connector and ECM/PCM.
Substitute a known-good ECM/PCM and recheck. lf symptom/indication goes away. replacelh6 original ECM/PCM.
Does the vokage drop?
Wire side of f€male terminals
11-182

1.After the engine starts, the lAc valve opens for a certain time. The amount of air is increased to raise the idle speed
about 150 - 300 rpm.
When the coolant temperature is tow, the IAC valve is opened to obtain the proper fast idle speed. The amount of
bypassed air is thus controlled in relation to the engine coolant temperature'
IOLE SPEED
lrpml
176
80
ENGI ECOOLANI TEMPERATURE
t" Fl
toc)
ll
't.Whentheid|espeedisoutofspeciiicationandthescantoo|doesnotindicateDiagnosticTroub|ecode(DTc)P0505
or P1508. check the following items:
. Adiust the idle speed {see page 11-220}
. Starter switch signal (see page 11-202)
. Air conditioning signal (see page l1-204)
. ALT FR signal (see Page 11-2081
' Brake switch signal (see page 11-210)
. PSP switch signal (excapt Canada model) (see page 11-212)
. A,/T gear position signal {see section 14, Dl6Y5 engine (CVT):
page 11-216). Clutch switch signal (D16Y5 engine with M/T) (see page 11-218)
. Hoses and connections
' IAC valve and its mounting O-rings
lf the above items are normal, substitute a known-good IAC valve and readjust the idle speed (see page 11-220)
|ftheid|espeedsti||cannotbeadjustedtospecification(andthescantoo|doesnotindicateDTcP0505orP]50S)
after IAC valve replacement. substitute a known-good ECM/PCM and recheck. lf symptom goes away, replace the
original ECM/PCM.