1994 HONDA INTEGRA idle air control

Troubleshooting
Troubleshooting Guide
NOTE: Across each row in the chart. the systems that could be sources of a symptom are ranked in the order they should
be inspected staning with O. Find the symptom in the left column, read across to the most likely source. then refer
to the page listed at the top of that column. lf inspection shows the system is OK, try the next mosr likely system O, etc,
* lf codes other then those listed above are indicated, count the number of blinks again. It the MIL is in fact blinking
^ these codes, replace the ECM.
qy, lf the MIL is on while the engine is running. connect the SCS shon connector to the service check connector. It no
code is displayed {MlL stays on steady), the back-up system is in operation.
Substitute a known-good ECM and recheck. lf the indication goes away, replace the original ECM.
USA:
MALFUNCTION
INDICATOR
LAMP {MIL)
CANADA: ----l CHECK-ltGl- ENGTNE- | - LTGHT
- { -1t-
* * *: 818C1 engine
1-32
SYMPTOM
PGM.FI
ENGINECONTROLMOOULE
HEATEOOXYGENSENSOR
MANIFOLOAESOLUTEPRESSURESENSOR
TOP DEAD CINTTR/CRANKSHAFTPOSTT|ON/CYLINDERPOSITION SENSOR
ENGINECOOLANTTEMPfRA.TURTSENSOR
THROTTTEPOStTtONSENSOR
INfAKE AIRTEMP€RA.TUREsar,rs0R
BARO.METRICPRESSURESENSOR
IGNITIONOUTPUTSIGNAL
vEHtct-ESPfEDSENSOR
11.4246, 47,5011-56l1-581l-6011-6211-641t-661r-68
MALFUNCTION INOICATORLAMP (MIU" TURNS ON1 lor:t:]:lrmr:- i;:i'-tK3t-16l-16l'-\-16l/-----\
-r:+r-
-{"Pr:-o_-16l-.z-\r6t/_-\
MALFUNCTION INOICATORLAMP (MIL)'' BLINKS:O. or-8.-D:o.:@.
o, O'l3l/__-\.E-o.:O: or tr]--i !l/ -i-\| 7 t-/__-\
--l-l-l r0 I/----\| 13 |z_---\
\.--r--l
I r5 t-/.---\-t 17 t-/-]-\
ENGINE WON'T STAffTo@@
DIFFICULT TO STARTENGIN€ WHEN COLO@@(9)o
IRREGULARIDLING
WHEN COTDFAST IDLEouT 0f sPtc@@
ROUGH IDLE@o
RPM TOOHIGH@@
RPM TOOLOW@
FREOUENTSTALLING
WHILE@@
AFTER@
POOnPERFOEM.ANCE
MISFIRE ORROUGHRUNNING@@@
FAITSEMISSIONTEST@@@
Loss 0FPOWER@@@

Troubleshooting
Self-diagnostic Procedures (cont'dl
':818C1 engine
a lf codes other than those listed above are indicated, verifv the code. lf the code indicated is not listed above, replace
rhe ECM.
a The MIL may come on, indicating a system problem when, in fact, there is a poor or intermittent electricalconnection.
First, check the electrical connections, clean or repair connections it necessary.
o The MIL and @ indicator light may light simultaneously when the Diagnostic Trouble Code (DTC) 6, 7 or 17. Check
the PGM-Fl system according to the PGM-Fl system troubleshooting, then recheck the l!! indicator light. ll it lights,
see page 14-5O, 51.
a The MIL does not come on when there is a malfunction in the A/T Fl signal or Electrical Load Detector (ELDI circuits.
However, it will indicate the codes when the Service Check Connector is shorted.
DIAGNOSTIC
TROUBLE
CODE (DTCISYSTEM INDICATEDPsge
oENGINE CONTROL MODULE IECM)11-42
,lHEATED OXYGEN SENSOR IHO25)1 1-46
aMANIFOLD ABSOLUTE PRESSURE {MAP SENSOR)11-52
4CRANKSHAFT POSITION (CKP SENSOR)1 1-56
oENGINE COOLANT TEMPERATURE (ECT SENSOR)11-58
THROTTLE POSITION (TP SENSOR}11-60
ITOP DEAD CENTER POSITION (TDC SENSORI1 1-56
9No. 1 CYLINDER POSITION (CYP SENSOR)1 1-56
10INTAKE AIR TEMPERATURE (IAT SENSOR)11-62
13BAROMETRIC PRESSURE (BARO SENSOR}1|-64
14IDLE AIR CONTROL (IAC VALVE}11-42
tcIGNITION OUTPUT SIGNAL11-66
toFUEL INJECTOR1't-102
17VEHICLE SPEED SENSOR {VSSI11-68
20ELECTRICAT LOAD DETECTOR (ELD)'t 1-70
21VARIABLE VALVE TIMING & VALVE LIFT ELECTRONIC CONTROL SOLENOID
VALVE {VTEC SOLENOID VALVE)'6-36
22VARIABLE VALVE TIMING & VALVE LIFT ELECTRONIC CONTROL PRESSURE
SWITCH (VTEC PRESSURE SWITCHI-6-38
23KNOCK SENSOR {KS}-11-7 4
30A/T FI SIGNAL A11-76
3'rA/T FI SIGNAL B1 1-76
4'lHEATED OXYGEN SENSOR (HO25} HEATER11-47
43FUEL SUPPLY SYSTEM1 1-50
11-36

PGM-FI System
System Description
ENGINE CONTROL MODULE (ECMIOUTPUTS
PGM-Fl System
The PGM-Fl system on this model is a sequential multipon fuel injection system,
Fuol Iniector Timing and Duration
The ECM contains memories tor the basic discharge durations at various engine speeds and manifold pressures. Thebasic discharge duration, after being read out from the memory, is turther modilied by signals sent from vanous sensofsto obtain the final discharge duration.
ldle Air Control
ldle Air Control Valve (lAC Vatve)
When the engine is cold, the A/C compressor is on, the transmission is in gear (A/T only) the brake pedal is depressed,the P/S load is high, or the alternalor is charging, the ECM controls current to the IAC Valve to maintain correct idle soeed.
lgnition Timing Controla The ECM contains mamories for basic ignition timing at various engine speeds and manifold pressures. lgnition timingis also adjusted for engine coolant temperature.a A Knock Control System is also used. when detonation is detected by the knock sensof. the ignition timing is retarded(B18Cl engine).
Other Control Functions
1. Starting Control
When the engine is started. the ECM provides a rich mixture by increasing fuel injector duration.2. Fuel Pump Control
a When the ignition switch is initially turned on, the ECM supplies ground to the PGM-Fl main relay that suppliescurrent to the fuel pump tor two seconds to pressurize the tuel system.a When the engine is running, the ECM supplies gfound to the PGM-Fl main relay that supplies current to the fuel pump.a When the engine is not running and the ignition is on, the ECM cuts ground to the PGM-FI main relav which cutscurrent to the fuel pump.
TDC/CKP/CYP Sensor
MAP Senso.
ECT Sensor
IAT Sensor
TP Sensor
HO2S
vss
BARO Sensor
ELD
Starter Signal
ALT FR Signal
Air Conditioning Signal
A/T Gear Position Signal
Battery Voltage {lcN. 1)
Brake Switch Signal
PSP Switch Signal
Knock Sensor'
VTEC Pressure Switchr
Fuel-lnjectors
PGM-FI Main Relay (Fuel Pump)
MIL
IAC Valve
A/C Compressor Clutch Relay
Radiator Fan Relav
Condenser Fan Relav
ALT
rcM
EVAP Purge Control Solenoid
HO2S Heater
VTEC Solenoid Valve'
IAB Control Solenoid Valve*
lFuet tnjector Timing and Duration]
I Electr..l"ldle Contr;il
Fit'e' contr; Funcrfit
l6tio; Ttntrlg c..trol
tEcM aack-,rp Functiorlsl
': 818C 1 €ngine
11-40

System Description
The idle speed ot lhe engine is controlled by the ldle Air Control {lAC) Valve.
The valve changes the amount ot air bypassing into the intake manifold in response to electric current controlled by the
ECM. When the IAC Valve is activated, the valve opens to maintain the proper idle speed.
#l' ----rTo FGM-FIMAINRELAY
VARIOUSSENSORS
IAC VALVE
FASTIDLETHERMOVALVE
INTAKE MAI{IFOLD
(cont'd)
BLK
r
11-79

ldle Control System
System Description (cont'd)
1 . Atter the engine slarts. the IAC valve opens for a censin time, The amount ot air is increased to raise the idle soeedabout 15O-3OO rom.
2. When the coolant temperature is low, the IAC valve is opened to obtain the proper fast idle speed. The amount ofbypassed air is thus controlled in relation to the engine coolant temperature.
IDI-E SPEEDlrpm)
176
80
ENGINECOOLANT TEMPERATURE
t"Fl(oct
11-80

ldle Control System
ldle Air Control (lACl Valve
lt6l- -l lf l- The Maltunction Indicator Lamp (MlL) indicates Diagnostic Trouble Code {DTC} 14: A problem in
' '- the ldle Air Control llAC) Valve circuit.
The IAC Valve changes the amount of air bypasEing the throttle body in respons€ to a current signal from the ECM in
order to maintain the proper idle speed.
ffi: r;611/ | /--T-\
- The MIL h.3 been report don,- With tho SCS shon connoctolconnoctod (soo pago 'l 'l -341,
cod6 14 is indicatod.
Do the ECM Reset Procedure (seepage 11-35).
With the engine running snd theaccelerator pedal releas€d, dis-conn€ct th€ 2P connector frorttho IAC valvo.
ls the MIL on and does it indicatecode 14?
htarmitlaot frlu]., aya-t.m i. OK !t thir tlft.
ll.rl drlv. mly ba nac-aaaaryl.Chack tor Doo. conn€c-tlonr oi loora wirca atC3O5 (loc.t.d .t |.ftlhock tow.tl, C424,Cl tB (lAC v.lvol .ndECM.
Disconnect the 2P connector fromthe IAC valve.
Sub.iituto . known{ood IACvdva lnd iotolt.
{To page 11-83}
11-82

ldle Control System
Fast ldle Thermo Valve
DEscliptlon
To prevent erratic running when the engine is warming
up, it is n€cessary to raise the idle speed. The fast idle
thermo valve is controlled by a thermowax plunger, When
the engine is cold. the engine coolant su.rounding the
thermowax contracts the plunger, allowing additional air
to be bypassed into the intake manifold so that the en-
gine idlss taster. When the engine reaches operating tem-
peratur€, the valve closss, reducing the amount of air
bypassing into the manifold.
FAST IDLE THERMOVALVE
AIN EYPASS VALVE
Inspaction
NOTE: The tast idle thermo valve is factory adiustsd;
it should not be disassombl€d.
1. Remove the intake air duct from the throttlg body.
2. Stan the engine.
3. Put your finger over ths lower port in throttle body
and make sure that there is 8ir flow with tho engine
cold (engine coolant temperatute below 86oF,
300c).
a lf not,
retest.
leplace the fast idle thermo valvs and
4.
o-Rr{GsReplace
llo kgf.m, 7 lbt.trl
Start the engine. Hold the sngine at 3.0OO rpm with
no load (A/T in I or @ position, M/T in neutral]
until the radiator fan comes on, then let it idl6.
Check thst valve is completely closed. lt not, air suc-
tion can be telt at the lower Don in the throttle body,
a It any suction is felt, the valve is leaking Check
engine coolant level and for air in tho engine
coolant system (see section 1O). ll OK, rsplace
the fast idle thermo valve and rechock.
11-94

ldle Control System
ldle Speed Setting (cont'd)
10.
9. ldle the engine for one minute with headlights {Low}
ON and check the idle sDeed.
ldla sp6od should bo;
81881 engine:
M/T750 i 50 rpm
An75O t 50 rpm
{in $ or p] positionl
818C1 engine: 75O 1 50 rpm
Turn the headlights off.
ldle the engine for one minute with heater tan switch
at Hl and air conditioner on, then check the idle
speeo.
ldls spood should bo;
81881 ongino:
M/T82O 1 50 rpm
AN840 1 50 rpm(in [N] or lll position)
818C1 engino: 85O t 50 nm
NOTE: lf the idle speed is not within specitication,
see System Troubleshooting Guide on page 1 1-78.
11-96