idle air control valve HONDA CR-V 1997 RD1-RD3 / 1.G User Guide

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
www.emanualpro.com

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.
www.emanualpro.com

ldle Control System
System Description
The idle speed of the engjne is controlled by the ldle Air Control (lAC) Valve'
The valve changes the amount of air bypassing into the intake manifold in response to electric current controlled by the
ECM/PCM. When the lAc valve is activated, the valve opens to maintain the proper idle speed.
YEL/ From PGM'FI
BLK TMAIN RELAY
VARIOUSSENSORS
4.
IAC VALVE
INTAKE MANIFOLD
After the engine starts, the IAC valve opens for a certain time. The amount of air is increased to raise the idle speed
about 150 - 300 rpm.
when the cootant temperature ts row, the lAc valve is opened to obtain the proper fast idle speed The amount o{
bvoassed air is thus controlled in relation to the engine coolant temperature
When the idle speed is out o{ specification and the scan tool does not indicate Diagnostic Trouble Code (DTC) P0505
or P1508, check the following items:
. Adjust the idle speed (see page 11-169, 170)
. Air conditioning signal (seepagell-1551
. ALT FR signal (see page 1l-159)
. Starter switch signal (see page 11-16'1)
. A,/T gear position signal (see section 14)
. PSP switch signal (seepagell-162)
. Brake switch signal (see page 11-165)
. Fast idlethermovalve (see page'11 168)
. Hoses and connecttons. IAC valve and its mounting O-rings
lf the above items are normat, suDslitute a known-good IAC valve and readjust the idle speed {see page 11-169, 170)
lf the idle speed still cannot be adjusted to specification (and the scan tool does not indicate DTC P0505 or Pl508)
after IAC valve reolacement, substitute a known-good ECM/PCM and recheck lf symptom goes away' replace the
original ECM/PCM.
11-149
www.emanualpro.com

ldle Control System
ldle Control System
I P0505 | The scan tool indicates Diagnostic T.ouble Code (DTCI PO5O5: ldlecontrol svstem mattunction.
NOTE: lf DTC P1508 is stored at the same time as DTC P0505, troubleshoot DTC P1508 first. then troubleshoot DTC p0505.
Possibls Cause
. IAC valve mechanical malfunction. Throttle body clogged port, improper adlustment. Intake manifold gasket leakaging. Intake air hose loose leakaging. Vacuum hose leakaging
a ECT sensor incorrect output. Throttle Position sensor incorrect output
Troubleshooting Flowchart
The MIL has been reDorted on.DTC P0505 is sto.ed.
Problem verificationi1. Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator Ian comes on, thenlet it idle.2. With the scan tool, check thelollowing items.- Throttle position should beapprox. 10% with the throt-tle {ully closed.- Engine coolant temperature shorJld be 194 - 205'F(90 - 96"C).lf they are not within thespec., repair the faulty sen-sor circuit.3 Check the engine speed atidle with no-load conditions:headlights, blower fan. reardefogger, radiator lan, and airconditioner are not operaling,
Inte.mittent failure. syltem is OKat this time.ls it 750 {730)* i 50 rpm?
ls il 700 (680)' rpm or less?
{To page 11-151)(To page 1'l-151)
l:'99 - 00 models
www.emanualpro.com

ldle Control System
ldle Air Control llAC) Valve
The scan tool indicates Diagnostic Trouble Code (DTC) Pl508: A probtem in the ldle Air Controt flAC) varvecircuit.
The IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from the ECM/PCM inorder to maintain the proper idle speed.
37 model;
IAC VALVE 2P CONNECTOR {C132}
,f rcp'# IYEL/BI.(II2f-1-d)
Y
Wir€ side of female terminals
PCM CONNECTOR A I32PI
tacvIBLK/BLU)
From AIR To INTAKECLEANER MANIFOLD
Wire side of female terminals
The MIL has beon .eport€d on.OIC Pl508 is sto.ed.
Problem veiification:1. Do the PCM Reset Procedure.2. Start the engine, and warm itup to normal operating tem-perature.
Inte.mittent failure, systcm b OKat thi3 time. Check tor poo. con-nections or loose wircs at C132(lAC v.lvel and at the PCM.
ls DTC Pl508 indicated?
Check lor an open in the wir6{lGPl lins}:1. Turn the ignition switch OFF.2. Disconnect the IAC valve 2Pconnector.3. Turn the ignition switch ON {ll).4. Measure voltage between bodyground and the IAC valve 2Pconnector term inal No.2.
Repair open in the wire trctwoontha IAC v!lv6 and the PGM-Flmain relly.
Chock for an opan o. short in thowi.e (lACv linel:1. Turn the ignition switch OFFand reconnect the IAC valve2P connector.2. Disconnect the PCM conneclorA (32P).
3. Turn the ignition switch ON {ll).4, Measure voltage betweenbody ground and PCM con-nector terminal A12.
{To page 1l-153)
www.emanualpro.com

ldle Control System
Fast ldle Thermo Valve lA/T)
Description
To prevent erratic running when the engine is warming
up, it is necessary to raise the idle speed. The fast idle
thermo valve is controlled by a thermowax plunger.
When the engine is cold, the engine coolant surround-
ing the thermowax contracts the plunger, allowing addi-
tional air to be bvDassed into the intake manifold so that
the engine idles faster. When the engine reaches operat-
ing temperature. the valve closes, reducing the amount
of air bypassing into the intake manifold.
IDLEADJUSTING
IDLETHERMOVALVE
AIR BYPASS VALVE
11-168
Inspgction
NOTE: The fast idle thermo valve is factory adjusted; it
should not be disassembled.
1. Remove the intake air duct from the throttle body.
2. Start the engine,
3. Put your finger over the lower port in throttle body,
and make sure that there is air flow with the engine
cold (engine coolant temperature below 86"F, 30'C).
lf there is no air flow, replace the fast idle thermo
valve and retest,
O-RINGSReplace.
11.0 kgfl.m, 7.2 lbl.ftl
Start the engine. Hold the engine at 3,000 rpm with no
load (in Park or neutral) until the radiator fan comes
on, then let it idle.
Check that the valve is completely closed. lf the valve
is leaking, the idle speed will drop when you cover the
lower pon. Check the engine coolant level and for air
in the engine cooling system {see section 10). lf the
cooling system is OK, replace the fast idle thermo
valve and recheck.
www.emanualpro.com

ldle Control System
ldle Speed Setting (cont'd)
38 - 0O mod6l3:
NOTE: Before setting the idle speed, check the follow-
ing items:- The MIL has not been reported on.- lgnition timing- Spark plugs
- Air cleaner- PCV system
1. Start the engine. Hold the engine at 3.000 rpm with
no load (in Park or neutral) until the radiator fan
comes on, then let it idle.
Connect a tachometer.
Disconnect the IAC valve 2P connector and the EVAP
purge control solenoid valve 2P connector.
CONTROLSOLENOID VALVE
SOLENOID VALVE
lf the engine stalls, restart the engine with the accel-
erato. pedal slightly depressed. Stabilize the rpm at
1,000, then slowly release the pedal until the engine
idles.
Che€k the idle in no-load conditions: headlights, blow-
er fan, rear defogger, radiator fan, and air conditioner
are not operating,
ldle speed should bo:
480 t 50 rpm {in PErk or noutrall
11-170
lf necessary, adjust the idle speed, by turning the
idle adjusting screw.
After adjusting the idle speed, recheck the ignition
timing (see section 4). lf it is out of spec, go back to
steo 4.tDt.E
6. Turn the ignition switch OFF.
7. Reconnect the 2P connectors to the IAC valve and
the EVAP purge control solenoid valve, then do the
ECM/PCM reset procedure.
8. Restart and idle the engine with no-load conditions
for one minute, then check the idle speed.
ldle speod should be:,98 model:
750 t 50 rpm tin Park or neutral)'9!l - 00 modsls:
730 i 50 lpm lin Psrk or neutral)
NOTE: lf the idle speed increases to 780 t 50 rpm(770 1 50 rpml*, this means the EVAP system is
purging the canister. To stop the purging temporari-
ly, raise the engine speed above 1,000 rpm with the
accelerator pedal, then slowly release the pedal.*: '99 - 00 models
9. Let the engine idle for one minute with the head-
lights (Low) ON, and check the idle speed.
ldle speed should be:
38 mod6l:
750 f 50 rpm (in Palk or neutrall'99 - 00 modols:
730 t 50 rpm (in Palk or neutral)
10. Turn the headlights off. Let the engine idle for one
minute with the heater fan switch at Hl and air con-
ditioner on, then check the idle speed.
ldls spqed should be:'98 model:
780 t 50 rpm (in Park or neutrall'99 - 00 mod€ls:
7701 50 rpm lin Park or neutral)
lf the idle speed is not within specification. see the
Symptom Chart on page 11-64.
ADJUSTING
www.emanualpro.com

Intake Air System
System Description
The system supplies air for all engine needs. lt consists of the intake air pipe, Air Cleaner, intake air duct, Throttle Body
(TB), ldle Air Control (lAC) Valve, fast idle thermo valve, and intake manifold. A resonator in the intake air pipe provides
additional silencing as air is drawn into the system.
INTAKE MANIFOLD
YEL| - - Fiom PGM'FI
BLK T MAIN RELAY
IDLETHERMO
lJ- _iuo'u'j"'
INTAKEAIR DUCT
vaRtousSENSORS
FESONATON
THROTTLEBODY (TB)
1 1-193
www.emanualpro.com

Troubleshooting
General Troubleshootin g
Check the following before you begin:
. Has the suspension been modified in a way that would affect steering?
. Are tire sizes, tire variety and air pressure correct?
. ls the steering wheel original equipment or equivalent?
. ls the power steering pump belt properly adjusted?
. ls steering fluid reservoir filled to proper level?
. ls the engine idle speed correct and steady?
Hard Steering (Check the power assist, see page 17-12. lf the force is over 29 N (3.0 kgl 6.6 lbfl, proceed with this troubleshooting.i
Abnormalthiidpressure (Iluidpressure is toohigh)
Relief pressuretoo low
Faulty valve body unit
Abnormal
Check the teed and return circuit lines and hosebetween the gearbox and pump for clogging anddeformation.
Normal line and hose
Check the pump fluid pressure(see page 17-16 or 17-17).Measure steady state lluid pres-
sure at idle with the pressure con-trol valve and the shut-off valve (it
so equipped) fully open.The fluid pressure should be 1,500kPa (15 kgf/cm,,213 psi)or less.
Normal
Check the flow control valve (see page 17 26).. Check the valv€ lor smooth movement in the hous-ing.. Check the relief valve for leaks.
Check the pump fluid pressure(see page 17-16 or l7-17).Measure pump relief pressure atidle with the pressure controlvalve and the shut'off valve lil soequipped) fully closed.The fluid pressure should be 6,9007,800 kPa (70 - 80 kgflcm,, 1,000- 1,140 psi).
Normal relief pressure
17-4
Go to page 17 5Faulty pump assemblyFaulty flow control valve
www.emanualpro.com

Uneven or rough steering.Ad,ust the rack gu ide (see page 17- 15).
ll the problem is not corrected byadjusting the rack guide, replacethe gearbox.
Adjust the belttension. Replace thebelt, if necessary (see page 17-14).Belt slipping on pulley.
lf the engine stalls when thewheel is turned while the vehicleis stopped or moving at lowspeed, adjust the idle speed (seesection 111.
ldle speed low or erratic.
Check power steering lluid level. lfthe level is excessively low checkfor leaks in the system. Add fluidto the specified level.
Air in reservoir, or check powersteering tluid level.
lf fluid level is OK, check O-ringsand seals on both ends of thepump inlet hose, and the P/Spump housing mating surlacesand drive shaft oil seal for suction leaks. Check the reservoir forcracks, Replace parts as neces-
Pump belt slipping on pulley(pump stops momentarily).Adjust the belt tension (see page17-14) or replace belt.
Check if pump pressure is normaland the gauge needle travel is 500kPa (5 kgl/cm,, 71 psi) or less.Check the flow control valve if theneedle travel exceeds 500 kPa (5kgflcm', 71 psi). lI the flow controlvalve is normal, replace the pumpas an assembly,
Install the power steering pres-sure gauge, Close the pressurecontrol valve and shut off valve (if
so equipped) fully and measurethe pump pressure (see page 17-16ot 17 17).
Steering wheel kicks backduring wide turns.
7-7
www.emanualpro.com