1998 ACURA INTEGRA valve

ldle Control System
System Description
The idle speed of the engine is controlled by the ldle Air Control (lAC) V8lve.
The valve changes the amount of 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.
81881 engine {B18Cl, B18C5 engines are similarl:
YELI - F.om PGM'FIBLK - MAIN RELAY
VARIOUS SENSORS
L
1 1-96

2.
1.
1.
2.
After the engine stans, the IAC valve opens for a certain time. The amount ol air is increased to raise the idle speed
about 150 - 300 rpm.
When the coolant temperature is low, 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.
IDLE SPEEDtrpm,
ENGINECOOLANT TEMPERATURE
140
50
104
40
-1 32
-20 0
176 ('F)
80 fcl
When the idle speed is out of specification and the scan tool does not indicate Diagnostic Trouble Code (DTC) P0505
or P'1508, check the following items:. Adiust the idle speed (see page '11-111)
' ALT FR signal (see page 11-101). Air conditioning signal {seepage'11-102)' Brake switch signal (seepagell-104)
. Starter switch signal (see page 11-1051. A,4 gear position signal (see page 1l 106) (A"/T)
. PSP switch signal (see page 11-108) (USA)
. Fast idle thermo valve (see page 11-110). Hoses and connections. IAC valve and its mounting O rings
ll the above items are normal, substitute a known-good IAC valve and readjust the idle speed (see page 'l I -1 1 l).
lf the idle speed still cannot be adjusted to specification (and the scan tool does not indicate DTC P0505 or P1508) after
IAC valve replacement, substitute a known-good ECM and recheck. lf symptom goes away, replace the original ECM.
11-97

ldle Control System
ldle Control System
i P0505 | fne scan tool indicates Diagnostic Trouble Code (DTC) P0505: ldle control system malfunction,
NOTE: ll DTC Pl508 is stored at the same time as DTC P0505, troubleshoor DTC P1508 first. then troubleshoot DTC P0505.
Possible Cause
. IAC valve mechanical malfunctiorr
. Fast idle thermo valve malfunction (A"/T)
. Throttle body clogged port, improper adjustment
. Intake manifold, gasket leakage
. Intake air hose loose, leakage
a Vacuum hoses leakage
. ECT sensor incorrect output
. Throttle Position sensor incorrect output
Troubleshooting Flowchart
Problem verification:1. Start the engine. Hold theengine at 3,000 rpm wath noload 1in Park or neutral) untilthe radiator fan comes on,then let it idle.2. With the scan tool, check thefollowing items.- Throttle position should beapprox. 10% with the throttle fully closed.Engine coolant tempera-ture should be 116 212F(80 - 100'c).lf they are not within thespec., repair the faulty sensor crrcuft,3 Check the engine speed atidle with no-load conditions:headlights, blower fan, reardefogger, radiator fan, and airconditioner are not operating,
- The MIL has been reported on.- DTC P0505 is stored.
ls it 750 t 50 rpm (81881,
818C1 engines), 800 I 50 rpm(818C5 engine)?
Intermittent failur6, svstsm is OKat this tim€.
ls it 550 rpm (81881,818C1
engines), 600 rpm {818C5enginelor less?
-98
(To page 11'99)(To page 11-99)

Chock th6 IAC vrlv.:Disconnect the 2P connector tromthe IAC valve.
ooes lhe engine speed droporlhe engine stall?
Adiu3t th. lb.r.l idle Bp..d lrocplgc 11-1111.lf it's impo3.iblo, clo.n tho portsin thc throftlc body.
Ch.ck th€ frtt idl. th.rmo vrlv.:1, Turn the ignition switch OFF.2. Remov€ th6 intake air ductfrom the throttle body.3. Slart the engine and let it idle.4. Put your finger on the lowerport in the thronle bodv.
Chack angina coobnt Lv.l and fo.ai. in th. cooling ry.l.m. It OK,r.place tha fatt ldla lftarmo valva.Does the engine speed drop?
Put your linger on the uppor portin the throttle body.
Chacl tor vrcuum leek3, m.lcilJa th6 throttlo valvo ir com-plotaly cloaad, rnd ropair aa nac-a3aatY,
ooes ihe engin6 speed drop?
Adiutt th€ idl. .p..d l..r p.g.11-1111. lf it'. impo3riblo, rcpl.c.thc IAC v.lvc.
{A/T model)----tLOWERPORT
L. _. _._. _. _. _.-l
IDLETHERMOVALVE
1 1-99

ldle Control System
Problem verification:'1. Do the ECM Feset Procedure.2. Sta rt the engine.
ldle Air Control (lAG) Valve
The scan tool indicates Diagnostic Trouble Code (DTC) P1508: A problem in the ldle Air Control (lAC) valve
crrcurt.
The IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from the Eclvl in
order to maintain the proper idle speed.FTom AIB To INTAKECLEANER MANIFOLD
IAC VALVE CONNECTOR IC116}
YES
WIRE SIDE OF FEMALE TERMINALS
ECM CONNECTOR A {32PI
Check for an open or short in thewire IIACV line):1. Turn the agnition switch OFFand reconnect the IAC valve
2. Disconnect the ECM connector A (32P).
3. Turn the ignition swatch ON (ll).
4. M easu re voltage betweenbody ground and ECM connector terminal A12.
IACV {8LK/BLU}
tacv{BLK/BI-UI
The MIL has been reoorted on.OTC Pl508 is stored.
lntermittent failure, svstem is OKat this time. Check for ooor con-nections or loose wires at C116{lAC valvel and ECM.
ls DTC P1508 indicated?
Check tor an open in lhe wirellGPl line):1. Turn the ignition switch OFF.2. Disconnect the IAC valve con
3. Turn the ignition switch ON (ll).
4. Measure voltage betlveen bodyground and the IACV connectorterminalNo.2.
Repair open in the wire betweenIAC valve and PGM-FI main relav-ls there battery voltage?
Repair open or shon in the wi.ebetween ECM {A12l and lAc valve.ls there battery voltage?
Check the IAC velve function:Momentarily connect ECM con-nector terminals A12 and A10with a jumper wire several times.
Does the IAC valve click?
Substitute a known-good ECMand rocheck. lf symptom/indica-tion goes away. replace the origi-nal ECM.
','*',,'Llu.9', I l112 15 16 17 1a1o20/
l--12u1 z"-if1za-2"' . '1 .
910
t-r '21
Wire side of female terminals
JUMPER WIRE
1-100

ldle Control System
Fast ldle Thermo Valve (A/T model onlylFast ldle I nermo valve (A/ | mooel
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 bvoassed into the intake manifold so that
the engine idles taster. When the engine reaches operat-
ing temperature, the valve closes. reducing the amount
of air bypassing into the manifold.
FAST IDLE THERMO
VALVE
VALVE
wAx
Inspection
NOTE: The fast idle thermo valve is factory adiusted; 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).
LOWERPORT
lf there is no air flow, replace the last idle thermo
valve and retest.
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 valve is completely closed. lf not, air suc-
tion can be felt at the lower port in the throttle body.
l{ any suction is felt, the valve is leaking. Check
engine coolant level and for air in the engine
coolant system (see section 10). It OK, replace the
fast idle thermo valve and recheck.
5.
{1.0 kg.m,7.2lbftl
l
11-110
lL.

ldle Speed Setting
IDLEADJUSTINGSCREW
7.
6.Turn the ignition switch OFF.
Reconnect the 2P connectors to the IAC valve and
the EVAP purge control solenoid valve, then do the
ECM reset procedures.
Restart and idle the engine with no-load conditions
for one minute, then check the idle speed.
NOTE: (Canada) Pullthe parking brake lever up.
Start the engine, then check that the headlights are off.
ldle speed should be;
Bl88l €ngine:
Mfi750 i 50 rpm
A/T750150 rpm (in Park or neutral)
818C1 engine:750 i 50 rpm
818C5 engine: 800 i 50 rpm
NOTE: 81881, Bl8Cl engines - It the idle speed
increases to *1rpm, this means the EVAP system ispurging the canister. To stop the purging termporarily.
raise the engine speed above 1,000 rpm with the
accelerator pedal, then slowly release the pedal.
*1: 81881 engine
M/T: 820 i 50 rpm
Ay'T: 840 t 50 rpm
818Cl engine
850 I 50 rpm
(cont'd)
Inspection/Adiustmont
NOTE:
. When setting the idle speed, checkthe following items:- The MIL has not been reported on.- lgnition timing
Spark plugs- Air cleaner- PCV system
. (Canada) Pull the parking brake lever up. Start the
engine, then check that the headlights are off.
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 2P connectors from the ldle Air
Control (lAC) valve and the EVAP purge control
solenoid valve.
2.
5.
if the engine stalls, restan the engine with the accel
erator pedal slightly depressed. Stabilize the rpm at
1,000, then slowly release the pedal until the engine
idles.
Check idling in no-load conditions: headlights, blower
fan, rear defogger, radiator fan, and air conditioner
are not ope€tlng.
ldlo speed should be;
B188l engine:
Mlf480 :l 50 rpm
A/T480 i 50 rpm (in Park or neutral)
B18C1 engine: /t80 t 50 rpm
818C5 sngine:550 t 50 rpm
lf necessary, adjust the idle speed, by turning theidle adjusting screw.
After adjusting the idle speed, recheck the ignition
timing {see section 23). lf it is out of spec, go back
to steo 4.

1r
;
J
I
Fuel Tank
Reolacement
!!@ Do not smoke while working on fuel system. Keep open flame away from your work a.ea.
1. Relieve the fuel pressure(seepagell-118).
2. Jack up the vehicle, and support it with jackstands.
3. Remove the drain bolt, and drain the fuel into an approved container.
4. Remove the rear seat (Hatchbackt Remove the spare tire lid and the protective cover), and access panels, and discon-
nect the 2P and 3P connectors.
5. Remove the EVAP two way valve cover and fuel hose protector, and disconnect the connectors.
6. Disconnect the hoses (see page 11-105). Slide back the clamps, then twist hoses as you pull, to avoid damaging them.
7. Place a tack, or other support, under the tank.
8. Remove the strap nuts, and let the straps fall free.
9. Remove the fuel tank.
lf it sticks on the undercoat applied to its mount, carefully pry it offthe mount.
10. lnstallthe drain bolt with a new washer, then coat the drain bolt with Noxrust 1248. Allow the Noxrust to dry tor 20
minutes.
11. Installthe remaining parts in the reverse order of removal.
ACCESSPANELS
CONNECTOR
2P CONNECTOR
3P CONNECTOR
2P CONNECTOR
EASE GASKETReplace.
FUEL GAUGESENDING UNIT
BASE GASKETReplace.
FUELTANK
38 N.m13.9 kgtm,28 tbf.ftl
EVAPTWO WAYVALVECOVERFUEL TANKSTNAPS
WAS}IERReplace.
9.8 N.m{1.0 kgf.m,7.2 tbt.tll
ORAIN BOLTilg N.m(5.0 k9f.m.36 rbf.ftl
FUEL HOSEPROTECTOR{
11-127