idle speed HONDA CR-V 1999 RD1-RD3 / 1.G User Guide

Troubleshooting
Troubleshooting Procedures (cont'dl
Symptom Chart
Listed below are symptoms and probable causes for problems that DO NOT cause the Malfunction Indicator Lamp (MlL) tocome on. lf the MIL was reported on, go to page 11-60.Troubleshoot each probable cause in the order listed (from left to right) until the symptom is eliminated,The probable cause and troubleshooting page reference can be found below.
Other Probable Causes for an engine that will not start:- Compression- Intake air leakage- Engine locked up- Timing belt- Starting system- Overheating- Battery
SYMPTOMPROBABLE CAUSE
Engine will not sta rt4, 2,3,5,20, 't5, 1
Hard starting2, 4, 12,17, 14, 't9
Cold fast idle too low7, a,9, 6, 17
Cold fast idle too high7,8,9,11,10
ldle speed fluctuates9,7,8, 't1, 10
Misfire or rough runningTroubleshoot for misfire on pages '11-126, 1|21LOl/\/ power2, 10,11, 13, '17, 18,20
Engine stalls2, 4, 12,1,20,9,5, 't6
Probable Cause List (For the DTC Ch8rt, see page ll-75.)
Probable CausePageSystem
Engine controt ruoaute (ecvtffi'I11-42
I 1-178Fuel oressure
PGM-Fl main relav
lgnition system
Crankshatt Position/Top Dead Center/Cylinder position sensor circuit
Intake Air Temperature (lAT) sensor ctrculr
ldle Air Control (lAC) Vatve
Fast idle thermo valve
ldle speed adjustment
Throttle body
Throftle cable
Manifold Absolute P."""rr"ffi
Throftle Position (TP) sensor
Barometric pressur" (gnno-
Ay'T gear position signal
Brake switch signal
Air Cleaner
Three Way Catalytic Converter (TWC)
Evaporative emission (EVAP) control
Contaminated fuel
1 1- 187
Section 4
5't1-'t31,146
6I 't-95
711-152
81'l-168
1 1- 169
1011-196'1111-'194
12'1 'l -90
1 1- 103
1411-137
15Section 14
161 1- 166
17r 1-194
181 1,199'1911-203
20
11-64
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ECM/PCM Data
By connecting the OBD ll scan tool or the Honda PGM Tester to the 16P data link connector (OLC), various data can be
retrieved from the ECM/PCM. The items listed in the table below conform to the SAE recommended practice
The Honda PGM Tester also reads data beyond that recommended by SAE.
understanding this data will help to find the causes of intermittent failures or engine problems.
NOTE:
The ',operating values" given below are approximate values and may be different depending on the environment and
the individual vehicle.
Unless noted otherwise. "at idle speed" means idling with the engine completely warmed up, transmission in position
Park or neutral and the A,./C and all accessories turned otf.
DataDesc.iptionOp€rating ValuoFreeze Data
Diagnostic
Trouble Code
(DTC)
lf the ECM/PCM detects a problem, it will store it as a
code consisting of one letter and tour numbers
Depending on the problem, an SAE-defined code (Poxxx)
or a Honda-defined code (P'lxxx) will be output to the
tester.
lf no problem is detected,
there is no output.
YES
Engine SpeedThe ECN4/PCN4 computes engine speed from the signals
sent from the Crankshaft Position sensor.
This data is used for determining the time and amount of
fuel iniection.
Nearly the same as
tachometer indication
At idle speed:'97 - 98 models:
750 t 50 rpm'99 - 00 models:
730 f 50 rpm
YES
Vehicle SpeedThe ECM/PCM converts pulse signals from the Vehicle
Speed Sensor (VSSI into speed data.
Nearly the same as
speedometer indicationYES
Manifold
Absolute
Pressure (MAP)
The absolute pressure caused in the intake manifold by
engine load and speed.
With engin6 stopped:
Nearly the same as atmo-
spheric pressure
At idle speed:
2a - 41 kPa {210 - 310
mmHg, 8.3 - 12.2 inHg)
YES
Engine Coolant
Temperature
{ECT)
The ECT sensor converts coolant temperature into volt-
age and signals the ECM/PCM. The sensor is a thermistor
whose internal resistance changes with coolant tempera-
ture. The ECM/PCM uses the voltage signals from the
ECT sensor to determine the amount of injected fuel
With cold engine:
Same as ambient temPer-
ature and IAT
With engine warmed uP:
approx. 163 - 2'12'F
(73 - 100"c)
YES
Heated Oxygen
Sensor (HO25)
(Primary,
Sensor 1)
(Secondary
Sensor 2)
The Heated Oxygen Sensor detects the oxygen content in
the exhaust gas and sends voltage signals to the
ECMiPCM. Based on these signals, the ECM/PCM controls
the airlfuel ratio. When the oxygen content is high (that is.
when the ratio is leaner than the stoichiometric ratio), the
voltage signal is lower.
When the orygen content is low (that is, when the ratio
is richer than the stoichiometric ratio), the voltage signal
is higher.
0.0 - 1.25 V
At idle speed:
about 0.1 - 0.9
NO
(cont'd)
1 1-65
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Troubleshooting
Troubleshooting Procedures (cont'd)
DataDescliptionOperating ValueFreezo Data
HO2S
Feedback
Loop Status
Loop status is indicated as "open" or "closed".
Closed: Based on the HO2S output, the ECM/pCM deter-mines the airlfuel ratio and controls the amount ofinjected fuel.
Open: ignoring HO2S output, the ECM/pCiM refers to sig,nals from the TP, MAP, and ECT sensors to control theamount of injected fuel.
At idle speed: closed
YES
Short Term
Fuel Trim
The airlfuel ratio correction coefficient for correcting theamount of injected fuel when HO2S feedback is in theclosed loop status. When the signal from the HO2S isweak, short term fuel trim gets higher, and the ECM/PCMincreases the amount of injected fuel. The airlfuel ratiogradually gets richer, causing a higher HO2S output.Consequently. the short term fuel trim is lowered. andthe ECM/PCM reduces the amount of injected fuel.This cycle keeps the airfuel ratio close to the stoichio-metric ratio when in closed looD status.
t:20y"
YES
Long Term
Fuel Trim
Long term fuel trim is computed from shon term fueltrim and indicates changes occuring in the fuel supplysystem over a long period.
lf long term fuel trim is higher than 1,00. the amount ofinjected fuel must be increased. lf it is lower than L00.the amount of injected fuel must be reduced.
! 20%
Intake Air
Temperature
(IAT)
The IAT sensor converts intake air temperature into volt-age and signals the ECrU/PCM. When intake air tempera-ture is low, the internal resistance of the sensorincreases, and the voltage signal is higher.
With cold engine:
Same as ambient temper-
ature and ECTYES
Throttle
Position
Based on the accelerator pedal position, the openingangle of the throttle valve is indicateo.At idle speed:
approx. 10%
lgnition
Timing
lgnition timing is the ignition advance angle set by theECM/PCM. The ECM/PCM matches ignition timing to thedriving conditions.
At idle speed: 16'1 4.
BTDC with the SCS ser-
vtce connector connected.
NO
Calculated
Load Value(cLV)
CLV is the engine load calculated from the MAp data.At idle speed:
2A - 410/o
At 2,500 rpm with no load:
13 - 260/o
YES
_
1 1_66
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PCM CONNECTOR C (31PI
ferminalnumberWirecolorTerminalnameDoscriptionSignal
'tBLUiREDCKFP (CKF SENSOR PSIDE)Detects CKF sensor.With engine running: pulses
2BLUCKPP (CKP SENSOR PSIDE)Detects CKP sensor.With engine running: pulses
3GRNTDCP (TDC SENSOR PSIDE)Detects TDC sensor.With engine running: pulses
4YELCYPP (CYP SENSOR PSIDE)Detects cYP sensor.With engine running: pulses
5BLU,frEDACS (A/C SWTTCHSIGNAL)Detects A,/C switch signal.With AJC switch ON: 0 VWith A,/C switch OFF: battery voltage
BLU/ORNSTS (STARTER SWITCHSIGNAL)
Detects starter switch signal.With starter switch ON (lll): bafteryvoltageWith staner switch OFF: 0 V
7BRNSCS (SERVICE CHECKSIGNAL)
Detects service check connectorsignal (the signal causing a DTCindication)
With the connector connected: 0 V
With the connector disconnected: about
5 V or battery voltage
8LT BLUK-LINESends and receives scan toolsrgnal.With ignition switch ON (ll): pulses
10WHT/BLUVBUUP)
(VOLTAGE BACKPower source tor the PCMcontrol circuit. Power source for
the DTC memory
Battery voltage at all times
11WHT/REDCKFM (CKF SENSOR MSIDE)Ground for CKF sensor signal.
12WHTCKPM (CKP SENSOR I\4SIDE)Ground lor CKP sensor signal.
13REDTDCM (TDC SENSOR MSIDE}Ground for TDC sensor signal.
14BLKCYPM (CKP SENSOR MSIDE}Ground for CYP sensor signal.
16GRN
PSPSW (P/S PRESSUREswtTcH)Detects PSP switch signal.At idle with steering wheel in straightahead position:0 VAt idle with steering wheel at full lock:
battery voltage
17WHT/REDALTF (ALTERNATOR FRSIGNAL)
Detects alternator FR signal.With fully warmed up engine running:
0 V-battery voltage {depending onelectrical load)
18BLUA/VHTVSS (VEHICLE SPEEDSENSOR)Detects VSS signal.Wirh ignition switch ON (ll) and frontwheels rotating: cycles 0 V - 5 V or bat-tery voltage
Wire side of femaie terminalsPCM CONNECTOR C {31PINOTE: Standard battery voltage is 12 V.
(cont'd)
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Troubleshooting
Powertrain Gontrol Module Terminal Arrangement -'97 Model (cont'd)
PCM CONNECTOR O {16PI
PCM CONNECTOR D (I6P)Wire side of f6male terminals
NOTE: Standard battery voltage is 12 V.
f.rminal
numbcrWir! colorT€rminal nam6DescriptionSignal
1RED/BLKTPS ffHROTTLE
POSITION SENSOR}
Detects TP sensor signal.With throttle fullv oDen: about 4.8 V
With throttle fullv closed: about 0.5 V
RE D,4/VHT
ECT (ENGINE COOLANT
TEMPERATURE
SENSOR
Detects ECT sensor signal.With ignition switch ON {ll): about
0.1 - 4.8 V (depending on engine
coolant temperature)
RED/GRN
MAP (MANIFOLD
ABSOLUTE PRESSURE
SENSOR)
Detects MAP sensor signal.With ignition switch ON (ll): about 3 V
At idle; about 1.0 V(depending on engine speed)
YEUREDVCCl (SENSOR
VOLTAGE)
Pow€r source for MAP sensor.With ignition switch ON (ll): about 5 V
With ignition switch OFF: 0 V
EG R N/WHT
BKSW (BRAKE
SWITCH)
Detects brake switch signal.With brake pedal released:0 V
With brake pedal depressed: battery
voltage
7WHT
PHO2S (PRIMARY
HEATED OXYGEN
SENSOR SENSOR 1)
Detects heated primary oxygen
sensor (sensor 1) signal.
With throttle fully opened from idle with
fully warmed up engine: above 0.6 V
With throttle quickly closed: below
0.4 v
8RED//E L
IAT (INTAKE AIR TEM.
PERATURE SENSOR)
Detects IAT sensor signal.With ignition switch ON lll): about
0.1 - 4.8 V (depending on intake air
temperaturel
10YEUBLUVCC2 (SENSOR VOLT-
AGEI
Provides sensor voltage.With ignition switch ON (ll): about 5 V
With ignition switch OFF: 0 V
11GRN/BLKSG2 (SENSOR
GROUND)
Sensor ground.Less than 1.0 V at all times
12GRN/WHTSGl (SENSOR
GROUND)
Ground for MAP sensor.Less than 1.0 V at all times
13RED/YE L
SHO2S SG(SECONDARY HEATED
OXYGEN SENSOR,
SENSOR 2 GROUND)
Ground for secondary heated
orygen sensor (sensor 2).
14WHT/RED
SHO2S (SECONDARY
HEATED OXYGEN
SENSOR, SENSOR 2)
Detects secondary heated
orygen sensor (sensor 2)
signal,
With throttle fully opened from idle with
fully warmed up engine; above 0.6 V
With throttle quickly closed: below
0.4 v
16*GRN/RED
EL (ELD)Detects ELD signal.With parking lights turned on at idle
about 2.5 - 3.5 V
With low beam headlights turned on
at idle: about 1.5 - 2.5V
1-70
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Engine/Powertrain Control Module Terminal Arrangement - 38 - 00 Models
ECM/PCM CONNECTOR A (32P}
,/./5aIsca
,/ l,/t5ItsTs
n2ls!uCI
Wire side ot female terminalsECM/FCM CONNECTOR A {32P)NOTE: Standard baftery voltage is '12 V.
D93criptionSignal
3BLU2WBS {EVAP BYPASSSOLENOID VALVE)Drives EVAP bvoass solonoid valve.With ignirion switch ON {ll)r battery voltage
LT GRNMHTVSV {EVAP CONTROL CANISTEB VENT SHUT VALVE)D.ives EVAP controlcanisler vent shutWith ig^ition switch ON (ll): battery voltage
5',BLUCRS (CRUISE CONTROL SIG'NAL)Shift Oown signalinputfrcm cruise conWhen cruise control is used: pulses
6RED/YEL
PCS (EVAP PURGE CONTROLSOLENOID VALVE)Drives EVAP purge controlsolonoid valve.With engins running, engine coolant, below 154'F(68'C)r battery voltageWith engine running, engine coolant, above 154"F{6a'C}r duty conl.olled
8ELIOWHTSO2SHTC (SECONDARVHEATED OXYGEN SENSORHEATER CONTROL)
Drives sacondary heated oxygen sensorWith ignition switch ON (ll): banery voltageWith fully warmed up engine running: duty
10BRNSCS (SERVICE CHECX SIGNAL)Detects seNics check conneclor signal(he signalcausing a DTC indicatjon)with rhe lerminal connected:0 vWith the rerminaldisconnectedrabout 5 v or
l4'rGRN/8LKD4IND (D4INDICATOR)+3DIND (D INDICATORTIDrives D4*3. Dr'indicaior light.W,rh 04' , O" indrcator light turned O batter,
With D4*3, D*. indicator light turned OFFr0 V
16GRNI/ELFLR (FUEL PUMP RELAY)Drivss fusl pump relay.0 V for iwo seconds after ru'nin9 ign'lion swilchON lll), then banery voltage
17AL|(/REDACC (I/C CLUTCH RELAY}Drives l,/C clurch rclay.With compressor ONr0 VWith compressor OFF: battery voltage
18GRN/ORNMIL (MALFUNCTION INDICA.TOR LIGHT)Driv€s MlL.With MlLturned ON:0 VWith MIL turned OFF: battery voltage
19BLUNEP (ENGINE SPEED PULSE)Outputs engine spsed pulse.With sngine runnin9: pulses
20GRNFANC {RADIATOR FAN CONTROL)Drives r6diator fan rslay.With radaator fan running:0 VWith radaatorfan stopped: battery vollage
218LU/t/ELK-LINESends and receiv€s scan toolsignal.With ignition switch ON (ll): p'rlses
23WHT/REDSHO2S (SECONDARY HEATEDOXYGEN SENSOR. SENSOR 2iDetects secondary h€at€d oxygen sensorWith throttle fully opened from idle wilh fullywalmed up engine: above 0.6 Vwith rhrottle quickly closed: below 0-4 V
21BLU/WHTSTS (STARTER SWITCH SIG,NAL}Dotocts srarter switch signal.Whh staner switch ON (lll): batlery voltageWith srarter switch OFF: 0 V
26GBNPSPSW {P/S PsESSUFESWITCH SIGNAL)Detecrs PSP switch signal.At idle with steeing wh€el in stBighl ahead position: 0 VAt idls with nee ng wheel al full lockr banory voltage
2fBLU/BEOACS (Ir'C SWTCH SIGNAL}D€tects ly'C switch signal.With Ay'C switch ON:0 VWith l/C swil€h OFF: about 5 V
2A'\WHT/NEDSLU {INTERLOCK CONTROLUNIT)Orives interlock control unil.With ignilion switch ON (ll)and brake pedaldepressed: battery vohage
29LT GRNPTANK (FUEL TANK PRES'SURE SENSOR)Detocts fueltank pressure sensor signal.With agnition switch ON (ll) and fuel fill capopensd; about 2.5 v
GBN/FEDEL (ELD}Detects ELD signal.Wirh paaing rightstumed on at idle:about 2.5 - 3.5 VWith low beam headlights tumed on at idle:about 1.5-2.5V
GRN/WHTBKSW (BRAKE SWTTCH)Dst€cts brake switch signal.Wirh brake pedal released:0 VWith brake pedal depressed: battery vollage
13: '98 modsl
15: USA(cont'd)
11-71
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ECM/PCM CONNECTOF C (31PI
Wire side o{ female terminal€ECM/PCM CONNECTOR C (31P)NOTE: Standard battery voltage is 12 V.
TermidalD.3criptionSignal
8LI(WHTPOzSHTC {PRIII4ABY HEATEDOXYGEN SENSOR HEATERCONTROL)
Drivss prim6ry h$ted oxygsn sensorWilh ignition switch ON (ll): baneryvoltsgeWith ftrllywarmsd up €ngine runnang: duty
2"WHT/GBNALTC (ALTERNATOR CON,TROL)Sonds alternalor control signsl.With fully wafmod up €ngine rnningr ban€ryvoltagoDu ng driving with small elsctrical lo6d: 0 v
3'1FED/8LUKS (KNOCK SENSOR)Dstects KS signal.With engine knockang: pulses
5WHT/REDALTF (ALTERNATOR FR SIG-NAL}Detects alternator FR signal.Wth fullywarmed up €ngine running:0 V-batteryvoltag€ {d€pending on slsctrical load)
1GRN,4trHTSG1 (SENSOR 680UND}Ground for l/tAP sensor.L€ss than 1.0 v 6t all times
8BLUCKPP (CKP SENSOF P SIDE)Dat€cls CKP s6nsor.With €ngin€ runningr puls€s
9CKPI.,I| {CKP SENSOF M SIDE)Ground for CKP s€nsor.
15PHO2S {PRIMARY HEATEDOXYGEN SENSOR, SENSOR 1)Detocts pfimary he6t6d oxygen ssnsor
{sonsor 1)signal.with ihfottls fully opened from idle with fully,
walm6d up engins: above 0.6 VWith throttlo quickly clossd: below 0.4 v
17RED/GRNMAP (MANIFOLD ABSOLUTEPRESSURE SENSOR)
D6tects MAP s€nsor sign6l.With ignition switch ON (ll):about 3 VAt idls: aboul 1.0 V {dspsnding on engine speed)
18GRN/BLKSG2 (SENSOB GNOUNDiLsss than 1.0 V at all tim€s
19YEUBEDVCCl {SENSOR VOLTAGE)Power soufce to MAP s€nsor.With ignition switch ON (ll): about 5 VWith ignition switch OFF:0 V
20GRNTDCP {TDC SENSOR P SIDE)Derecis TDC sensor.With engine funning: Pulses
2lREDTDCM ITDC SENSOR M SID€)Ground for TDC sensor.
22BLU/REDCKFP (CKF SENSOR PSIDE)Dstscts CKF s€nsor.With sngins running: pulsss
23BLU/WHTVSS (VEHICLE SPEED SEN-soR)Dstscrs vss signal.With ignition switch ON (ll)and front wheelsrotaringrcyclss 0 v- 6bout 5 V or ban€ry voltage
25RED//ELIAT (INTAKE AIR TEMPERA'TURE SENSOB)Detacts IAT sensor signal.With igniiion switch ON (ll): about 0.1 - 4.8 V(d€p€nding on iniate air t€mp€raturc)
26REO/WHTECT {ENCINE COOLANTTEMPERATURE SENSOR)oetscts ECT sensor signal.With ignition switch ON (ll): about 0.1 4.8 V
{doponding on 6ngin€ coolanl lemper6tu16)
27RED/BLKTPS (THROTTLE POSITIONSENSOR)Dotects TP sensor signrl.with rhrottls fully op€n: aboui 4.8 vwith throtrl6 fullyclosed: about 0.5 v
2AYEUBLUVCC2lSENSOR VOLTAG€}Provid€s s€nsor voltage.With ignilion switch ON (ll): about 5 VWhh ignition switch OFF: 0 V
29YELCYPP ICYP SENSO8 P SIDE)Dsrscts CYP sensor.With €ngins runningr pulsss
30BLKCYPM (CYP SENSOR M SIDE)Ground for CYP sansor.
31WHT/REDCKFM {CKF SENSOR M SIDE)6.ound lof CKF ssnsor signal.
11. AfT 13. '94 model'2:M/T 14:'99- 0o modsls.5: USA
(cont'd)
11-73
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DTC(MlL indicationlDotection ltomProbable CausePage
P0500 t17)*,
Vehicle SpeedSensor CircuitMalfunction
Vehicle Speed SensorVehicle Speed Sensor circu itECtVI1 1-135
P0501 l17J*1
Vehicle SpeedSensor CircuitMalfunction
Vehicle Speed SensorVehicle Speed Sensor circuitPCM11-135
P0505 (14)ldle ControlSystemMalfunction
IAC valveThrottle BodyFast idle thermo valve*11 ']- 150
P0700P0715PO720P0730P0740P0753P0758
AutomaticTransaxle
Section l4
P1106 (13)BarometricPressure CircuitRange/Performance Problem
ECM/PCM (Baro sensor)
11-137
P1107 (13)BarometricPressure CircuitLow InPut
. ECM/PCM {Baro sensor)11-137
P1108 (13)BarometricPressure CircuitHigh Inpur
ECM/PCM {Baro sensor)11,137
P1121 (7)Throttle PositionLower ThanExpected
. TP sensor11-109
P1122 (7)Throttle PositionHigher ThanExpected
' TP sensor1 1-'109
P112a (5)Manifold AbsolutePressure Lower ThanExpected
. MAP sensor11-94
P1129 (5)Manifold AbsolutePressure HiqherThanExpected
' MAP sensor1l-94
P1297 (20)Electrical LoadDetector CircuitLow Input
Electrical Load DetectorElectrical Load Detector circuitECM/PCM1 1- 138
P1298 (20)Electrical LoadDetector CircuitHigh Input
Electrical Load DetectorElectrical Load Detector circuitECM/PCM11-140
P1300'3
P0301P0302P0303P0304
7l721314
Random lvlisfirelgnition systemFuel supply systemMAP sensorIAC valveContaminated fuelLack offuel
11-126
*: These DTCS will be indicated by the blinking of the Malfunction Indicator Lamp {MlL} with the SCS service connector
connected.**:The E (E])+s indicator light and the Malfunction Indicator Lamp (MlL) may come on simultaneously.*1:A,./T "3: '97 model +5: '99 - 00 models*2: M/T *4:'98 model
{cont'd)
11-77
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PGM-FI System
System Description
INPUTS
CKP/TDC/CYP Sensor
CKF Sensor
MAP Sensor
ECT Sensor
IAT Sensor
TP Sensor
Primary HO2S
Secondary H02S
vss
KS*5
BARO Sensor
ELD*6
Starter Signal
ALT FR Signal
Air Conditioning Signal
Ay'T Gear Position Signal*1
Baftery Voltage (lGN.1)
Brake Switch Signal
PSP Switch Signal
Fuel Tank Pressuae Sensor*4. *5
Countershaft Speed Sensor*1
Mainshaft Speed Sensor*r
OVER-DRIVE Switch Signal*s
ENGINE CONTROL MODULE (ECM)/
POWERTRAIN CONTROL MODULE (PCM) OUTPUTS
|iuel 1"j""- Th,rhg ""d Drrafr";-l
Et*-.nt"tdt"cont.orl
to,r*,c;;trffi;]
l.----.---:. .Lrgnrnon |lmrng Lonrror I
Ecir/PcM B*k',p Fr""il]
m;"t-ll-r*'io*l
Fuel Injectors
PGM-Fl Main Relay (Fuel Pump)
MIL
IAC Valve
Ay'C Compressor Clutch Relay
Radiator Fan Relay
Condenser Fan Relay
ALT
tcM
EVAP Purge Control Solenoid
Valve
Primary HO2S Heater
Secondary H02S HeaterEVAP Bypass Solenoid Valve*a *5
EVAP Control Canister Vent Shut
DLC
Lock-up Control Solenoid Valve*l
Shift Control Solenoid Valve*1
Ay'T Clutch Pressure Control
Solenoid Valve*1
D4 Indicator Light'1 *3, *a
D Indicator Light,l *5
OVER-DRIVE OFF Indicator
Lighl*t *:
*1: A/T {3:'97 model'2: M/f +4:'98 model*5: '99 - 00 models"6: USA
PGM-Fl System
The PGM-Fl system on this model is a sequential multiport fuel injection system.
Fuel iniecior Timing and Duration
The ECM/PCM contains memories for the basic discharge durations at various engine speeds and manifold pressure. The
basic discharge duration, after being read out from the memory, is further modified by signals sent from various sensors
to obtain the final discharge duration.
ldle Air Control
ldle Air Control Valve (lAC Valve)
When the engine is cold, the Ay'C compressor is on, the transmission is in gear, the brake pedal is depressed, the P/S load
is high, or the alternator is charging, the ECM/PCM controls current to the IAC Valve to maintain the correct idle speed.
lgnition Timing Control
o The ECM/PCM contains memories for basic ionition timing at various engine speeds and manifold air flow rates.
lgnition timing is also adjusted for engine coolant temperature.
. A knock control system was adopted which sets the ideal ig nition timing for the octane rating of the gasoline used.*s
Other Control Funstions
1. Starting Control
When the engine is started. the ECM/PCM provides a rich mixture by increasing fuel injector duration.
2. Fuel Pump Control
. When the ignition switch is initially turned on (ll). the ECMiPCM suppli€s ground to the PGM-FI main relay that
supplies current to the fuel pump for two seconds to pressurize the fuel system.
. When the engine is running, the ECM/PCM supplies ground to the PGM-FI main relay that supplies current to the
fuel oumo.
. When the engine is not running and the ignition is on, the ECM/PCM cuts ground to the PGM-FI main relay which
cuts current to the fuel pump.
1 1-80
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Fuel Cut-off Control
. During deceleration with the throttle valve closed, current to the fuel injectors iscutoffto improvefuel economyat
speeds over 970 rpm ('97 - 98 models), 920 rpm ('99 - 00 modelsl.
. Fuel cut-off action also takes place when engine speed exceeds 6,500 rpm ('97 - 98 models), 6900 rpm ('99 - 00
models), regardless of the position of the throttle valve, to protect the engine from over-rewing.
With Ay'T model. the PCM cuts the fuel at engine speeds over 5,000 rpm when the vehicle is not moving.*'
4,./C Comoressor Clutch Relav
When the ECM/PCM receives a demand for cooling from the air conditioning system, it delays the compressor from
being energized, and enriches the mixture to assure a smooth transition to the Ay'C mode.
Evaporative Emission (EVAP) Purge Control Solenoid Valve
When the engine coolant temperature is above 154"F (68'C), the ECM/PCM controls the EVAP purge control solenoid
valve which controls vacuum to the EVAP purge control canister,
Alternator Control
The system controls the voltage generated at the alternator in accordance with the electrical load and driving mode.
which reduces the engine load to improve the fuel economy.
PCM Fail-saf e/Back-up Functions
1. Fail-safe Function
When an abnormality occurs in a signal from a sensor, the ECM/PCM ignores that signal and assumes a pre-pre
grammed value for that sensor that allows the engine to continue to run.
2. Back-up Function
When an abnormality occurs in the ECM/PCM itself, the fuel injectors are controlled by a back-up circuit independent
of the system in order to permit minimal driving.
3. Self-diagnosis Function IMalfunction Indicator Lamp (MlL)l
When an abnormality occurs in a signal from a sensor, the ECM/PCM supplies ground for the MIL and stores the DTC
in erasable memory. When the ignition is initially turned on {ll), the ECM/PCM supplies ground for the MIL for two
seconds to check the MIL bulb condition.
4. Two Trio Detection Method
To prevent false indications, the Two Trip Detection Method is used for the HO2S*1, fuel metering-related. idle control
system, ECT sensor and EVAP control system self-diagnostic functions. When an abnormality occurs, the ECM/PCM
stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFF and ON (ll) again,
the ECM/PCM informs the driver by lighting the MlL. However, to ease troubleshooting, this function is cancelled
when you jump the service check connector, The MIL will then blink immediately when an abnormality occurs.
5. Two (or Three) Driving Cycle Detection Method {'97 model)
A "Driving Cycle" consists of starting the engine, beginning closed loop operation, and stopping the engine. lf misfir-
ing that increases emissions or EVAP control system malfunction is detected during two consecutive driving cycles.
or TWC deterioration is detected during three consecutive driving cycles, the ECM/PCM turns the MIL on. However, to
ease troubleshooting, this function is cancelled when you jump the service check connector. The MIL will then blink
immediately when an abnormality occurs.
*1: '97 - 98 models*2: '99 - 00 models
5.
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