1994 HONDA INTEGRA engine

ldle Gontrol System
System Troubleshooting Guide
NOTE:
a Acrosa each row in the chan, the sub-systems that could be sources of a symptom are ranked in the order they should
be inspected, starting with O. Find the symptom in the left column, read across to the most likely source, then reler
to the page listsd at ths top ot that column. It inspection showa the system is OK, try the next system @, etc.
a lf the idle speed is out of sp€cification and th€ Malfunction Indicator Lamp {MlL) does not blink Diagnostic Trouble
Code (DTC) 14, 9o to inspection describ€d on pags 1 1-81.
PAGE
SYMPTOM
IDTIOJUSTIiSCREW
IDLE AIRc0NTROt-
AIRcoN0fTtoNtitcSIGNAL
ALTER.NAION FNSIGNAL
AUTOMATICIRAI{SA(LEGtARP0sm0 stGIAt
ERAK€swrTcHSIGNAL
STARTERswtTcHSIGNAT
POWERSTEERII'IGPffESSUREswncHSIGNAL
FAST IOLETHERMO
HOSESANOCONNEC.TIONS
11-9511-4211-841 1-8611-8811-9011-92I 1-9311-94
DIFFICULT TO STARTENGINE WHEN COLD@o
WHEN COLD FAST IDLE OUT OFSPEC l1,0OO- 2,0OO rpm|o@o
ROUGH IDLEo
WHEN WARM RPM TOO HIGHooo
WHEN
TOO LOW
ldl6 3p6od b b€lowspecitisd rpm (no loadl@o
ldla 5p66d doos nolincraas€ alter initialo
On mod6l3 with auto-matic transmBsion, thsidlo sp€ed drops in 963ro
ldl6 sp€eds drops when8ir condilioner in ONoo
ldls spo6d drops when6ts6iing wh66l i6 turninC@o
ldla spoed lluctust63with alactrical loado
FREOUENTSTALLING
WHILE WARMING UP@o
AFTER WARMING UPo@
FAILS EMISSION TESTo
11-78
.,Hilffirl|,

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
Alternator (ALTI FR Signal
This signals the ECM when the Alternator (ALT) as charging.
D9 l+)
Inspection ot ALT FR Sign.l.
Connect the tost harness betweenthe ECM and connectors. Discon-nect "D" connector from themain wire harnoss only, not theECM lsee page 11-37).
Turn the ignition switch ON.
Measure voltage between D9 (+ )terminal and A26 {-}terminal.
Sub{inno s known-good ECMand redrack. It pro.ctibod volt gola now availablg, ropllco tha orlg-inal ECM.
ls there approx. 5 V?
Turn the ignition switch OFF.
Reconnect "D" connector to themain wire harness,
Start tho engino. Hold the engine
!L3,099 rpm with no load (A/T in
LN] or El position, M/T in neutral)until the radiator tan comes on,rhen let it idle.
Measuro voltage between Dg (fl
terminal and 426 (- I terminal.
Does the voltage decreasewhen headlights and .eardelogger are turned on?Turn ths ignition switch OFF.
ALT FR rignal is OK.
o oo oo o ooooo
ooooooooooo
Voh.go?
ooooooooooo
ooooooooooo
1 1-86
(To page 1 1-87)
=-

ldle Gontrol System
Startel Switch Signal
This signals the ECM when the engine is cranking.
BATTERYVOLTAGE?
NOTE:a M/T: Clutch pedal must beoeprgsseo.a A/T: Trsnsmission in lll or LIJ position.
11-92
ooooooooooooo
oooooooooooo
A26 {-}Connect the lest harness botweenthe ECM and connector (see page
11,37).
Measure voltage between 89 (+)
terminal and 426 (-) terminalwith the ignition switch in thestart position.
Inspect No. 18 STARTER SIGNAL{7.5 A) fuse in the under-dashfuse/relav box.ls there batterv voltage?
- Roplac. No. 18STARTER SIG AL(7.5 A) lurc,- Rrpsir lhort In BLU/WHT wir. batwccnECM (89) .nd No.18 STARTER SIG.t{AL {7.5 Al 1u..,PiGM-Fl fi.ln rol.y.
R.palr opon in BLU/WHT wir6 b6-tw€.n ECM lB9l and t{o, 18STARTER SIGNAL 17.5 Al lu.o.
Startor .witch .ign.l is OK.

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 Speed Setting
Inspoction/Adiustment
NOTE:
a When the idle speed set, check the following items:
- The MIL has not been reported on.- lgnition timing- Spark plugs- Air cleaner- PCV svstem
a (Canada) Pullthe parking brake lever up. Stan the en-
gine, then check that the headlights are off.
1 Start the engine. Hold the engine at 3,000 rpm with
no load (A/T in S or @ position, M/T in neutral)
until the radiator tan comes on, then let it idle.
2. Connect a tachometer.
3. Disconnect the 2P connectot trom the ldle Air Con-
trol {lAC) valve.
Start the engine with the sccelerator pedal slightly
depressed. Stabilize the rpm at 1 ,OOO, then slowly
release the pedal until the engine idles.
Check idling in no-load conditions: headlights, blower
fan, rear defogger, radiator fan, and ai. conditioner
are not operatrng.
ldl€ spood should bo;
81881 ongino:
MlT48O ! 50 rym
An48O I 50 rpm
lin@or@oosition)
818C7 engine:48O ! 50 rym
Adjust the idle speed, if necessary, by turnmg the
idle adiusting screw.
NOTE: After adiust the idle speed in this step, check
the ignition timing (see section 231.
lf it is out ot spec. go back to step 4.
4.
e
Turn the ignition switch OFF.
Reconnect the 2P connector on the IAC valve, then
remove the BACK UP (7.5 A) fuse in the under-hood
tuse/relav box for 1O seconds to reset the ECM.
Restart 8nd idle the engine with no-load conditions
for one minute, then check the idle speed.
NOTE: (Canada) Pull the parking brake lever up.
Start the engine, then check that the headlights ate
off.
ldlo speed should be;
81881 ongino:
MTf75O ! 50 rpm
AIT75O t 50 rpm
(in[]or@positionl
818C1 engine: 750 1 50 rpm
(cont'd)
11-95