1999 HONDA CIVIC idle valve

ldle Control System
ldle Air Control (lAC) Valve ('96 - 98 A/T and Dl6Y7 enginel
The (Rotary) IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from theECM/PCM in order to maintain the proper idle speed,
BIMETAL
VALVESTOPPER
1P1509 Thescantool indicates Diagnostic Trouble Code (DTC) P1509: A problem in the idle Air Control (tAC)valve circuit.
ECM/PCM CONNECTOR A I32PIPGl IBLKI
IAC VALVE 3P CONNECIOR
IACV NIACV P
IGP
Terminal side of maleterminals
*: IACV N line
1 1-198
The MIL has b€€n roported on.DTC P1509 is stored.
Problem verification:1. Do the ECM/PCM Reset Proce-oure.2. Turn the ignition switch ON (ll).
Intermittent failura, systom ia OKat this time. Check tor poo. con-noctions or loose wires at C109llAC valve) and ECM/PCM.
ls DTC P1509 indicated?
Check for an opon in the wirer{PG lines):Measure voltage between bodvground and ECM/PCII connectorterminals A10 and A23 individu
Repair op€n in the wires betwoenECM/PCM and G101 llocated attho thermostat housing).
ls there more than 1.0 V?
Chock th€ ECM/PCM inpui volt-agel1. Turn the ignition switch OFF.2. Disconnect ECM/PCM connec-tor A (32P)from the ECM/PCM.3. Turn the ignition switch ON (ll).4. Measu re voltage betweenbody ground and ECM/PCMconnector terminals A14 andA13* individually.
Ch6ck th6 IAC valve:1. Turn the ignition switch OFF.2. Disconnect the IAC valve 3Pconnector,3, Measure resistance betweenIAC valve 3P connector termi-nal No.2 and terminals No. 1and 3 individually.
ls there 16 - 28 g?
Substitute a known-good ECM/PCM and recheck. lf symptom/indication goos away, replaceth€ origin.l ECM/PCM.
SHAFT
rAcv N loRNl*
(To page 11-199)
Wire side of lemale terminals
123a56El011
121314r5161718t9202:22321
272AA30
IACV P {BLK/BLUI

ldle Gontrol System
The (Rotary) IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from the
ECM/PCM in order to maintain the proper idle speed.BIMETALHOLDER
BIMETAL
SHAFTVALVESTOPPER
ECM/PCM CONNECTOR B {25P}
(To page 11-201)
IAC VALVE 3P CONNECTOR
IACV NIACV P
ldle Air Control {lACl Valve ('99 - 00 A/T and Dl6Y7 enginel
YES
1P1509 lThescantool indicates Diagnostic Trouble Code (DTC) P1509:A problem inthe idleAirControl (lAC)valve circuit.
IGP
Terminal side of maleterminals
Sub3titute e known-good ECM/PCM .nd recheck. lf 3vmptom/indicalion goos away, replac6thc original ECM/PCM.
*: IACV N line
11-200
Tho MIL has b€en reported on.OTC P1509 is sto.ed.
Problem verilicationr1. Do the ECM/PCM Reset Proce-dure.2. Turn the ignition switch ON (ll).
Intermittont tailure, sy3tem i3 OKat thb time. Check for poor con'noctions or loose wiros at C109(lAC velvel and ECM/PCM.
ls DTC P1509 indicated?
Check for an oDen in the wilosIPG linesl:Measure voltage between bodyground and ECM/PCM connectorterminals 82 and 810 individually.
Ropail open in the wires be'tw€enECM/PCM .nd G101 llocated .tthe the.mostat housingl.ls there more than 1.0 V?
Check tho ECM/PCM input volt-age:1. Turn the ignition switch OFF.2. Disconnect ECM/PCM connec-tor A (32P)trom the ECM/PCM.3. Turn the ignition switch ON (ll).
4, Measure voltage betweenbody ground and ECM/PCMconnector terminals 86 and815* individually.
Chock the IAC v.lve:1. Turn the ignition sw;tch OFF.2. Disconnect the IAC valve 3Pconnoctor.3. Measure resistance betweenIAC valve 3P connector termi'nal No. 2 and terminals No. 1and 3 individually.
ls there 16 - 28 O?
Wire side of female terminals

ldle Control System
ldle Speed Setting
Inspection/Adiustmenl
'96, '97 Dl6Y5. '96 - 00 Dl5Y8 sngine with M/T
NOTE:
. Before setting the idle speed, check the following
items:- The MIL has not been reported on.- lgnition timing- Spark plugs- Air cleaner- PCV system
o (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 withno load (taansmission in neutral) until the radiatorfan comes on, then let it idle.
2. Connect a tachometer.
3. Disconnect the IAC valve connector.
4.lf the engine stalls, restart the engine with the accel-
erator pedal slightly depressed. Stabilize the rpm at1,000, then slowly release the pedal until the engineidles.
Check idling in no-load conditionsr headlights. blowerfan. rear defogger, radiator fan, and air conditioner
are not operating.
ldle spsed should be:
450 1 50 rpm
11-220
Adjust the idle speed, if necessary, by removing thecap and turning the idle adjusting screw.
NOTE; After adjusting the idle speed in this step,recheck the ignition timing (see section 23).
lf it is out of spec, go back to step 4.
IDLE
6. Turn the ignition switch OFF.
7. Reconnect the 2P connector on the IAC valve, then
do the ECM reset procedure.
8. Restart and idle the engine with no-load conditionsfor one minute, then check the idle speed.
NOTE: (Canada) Pull the parking brake lever up.Start the engine, then check that the headlights areoff.
ldle sp€sd should b€:
670 i 50 rpm IUSA)750 t 50 rpm {Canada}
9. ldle the engine tor one minute with headlights {Low)ON. and check the idle speed.
ldle speed should be:
750 :r 50 rpm
10. Turn the headlights off. ldle the engine for oneminute with heater fan switch at Hl and air conditioneron, then check the idle speed.
ldle speed should be:
810150 rpm
NOTE: lf the idle speed is not within specification,see Symptom Chan on page 11-84.

t
t
I
'96.'97 D16Y5 engine with CVT,'96 - 00 D16Y8 ongins
with A/T and'96 - 00 Dl6Y7 €ngine
Adiust the idle speed using a Honda PGM Tester if pos-
sible. lf not, use the following procedure:
NOTEI
. Leave the IAC valve connected
. Betore setting the idle speed. check the following
items:- The MIL has not been reported on'
- lgnition timing
- Spark Plugs- Air cleaner- PCV system
1. Connect a tachometer.
2. Start the engine. Hold the engine at 3,000 rpm wirh
no load (in Park or neutral) until the radiator fan
comes on, then let it idle.
3. Check the idle speed with no-load conditions: head-
iights, blower fan, rear defogger, radiator fan, and
air conditioner are not operatlng
ldl€ spoed should be:
USA:
D16Y5 engine with CVT, D16Y7 engine with A/T'
Dl6YB engine with A/T:
700 :r 50 rpm (in E or El Positionl
D16Y7 engine with M/T:
670 i 50 rpm
Canada:
Dl6Y8 sngin€, Dl6Y7 engins:
M/T750 t 50 rpm
NT750 1 50 rpm (in E or El Position)
Adjust the idle speed, if necessary, by removing the
cap and turning the idle adiusting screw 1/2-turn
clockwise or counterclockwise
D16Y5, D16Y8 engine:
IDLEADJUSTING
Dl6f, ongine:
NOTE: When you remove the ACL housing, do not
disconnect the IAT sensor connector
After turning the idle adjusting scrow 1/2-turn'
check the idle speed again. lf it is out of spec, turn
the idle adjusting screw 1/2-turn agaan'
NOTE: Do not turn the idle adjusting screw more
than 1/2-turn without checking the idle speed'
ldle the engine for one minute with heater fan
switch at Hl and air conditioner on, then check the
idle speed.
ldle speed should be:
M/T810150 rpm
A/T. CvT810 t 50 rpm (in El or E Position)
NOTE:
. Do not turn the idle adjusting screw when the air
conditioner is on.
. lf the idle speed is not within specification. see
Symptom Chart on page 11-84 (cont'd)
11-221

ldle Control System
ldle Speed Setting (cont'dl
Inspeqtion/Adiustment
38 D16Y5 engine whh M/T,'99 - 00 81642 engine
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 withno load (transmission in neutral) until the radiatorfan comes on, then let it idle.
Connect a tachometer.
Disconnect the IAC valve 2P connector and the EVAPpurge controlsolenoid valve 2P connector.
EVAP PURGECONTROLSOLENOID VALVE
lf the engine stalls, restart the engine with the accel-erator pedal slightly depressed. Stabilize the rpm at1.000, then slowly release the pedal until the engineidles.
Check idling in no-load conditions: headlights, blowerfan, rear defogger, radiator fan, and air conditionerare not operating.
ldl€ speed should be:
450 i 50 rpm
11-222
lf necessary, adjust the idle speed, by removrng lnecap and turning the idle adjusting screw.After adjusting the idle speed recheck the ignitlontiming (see section 23). lf it is out of spec, go backto step 4. |DLE
6. Turn the ignition switch OFF.
7. Reconnect the 2P connectors to the IAC valve andthe EVAP purge control solenoid valve, then do theECM reset procedure.
8. Restart and idle the engine with no-load conditionsfor one minute, then check the idle sDeed.ldle speed should bo:
USA:
D16Y5 engine: 670 i 50 rpm
81642 engine: 700 i 50 rpm
Canada:
81642 engine: 750 t 50 rpm
NOTE: lf the idle speed increases to 8lO t 50 rpm,this means the EVAP system is purging the canister.To stop the purging temporarily, raise the enginespeed above 1,000 rpm with the accelerator pedal,
then slowly release the pedal.
9. ldle the engine for one minute with headlights(Low) ON. and check the idle speed.
ldle speed should be:
750 i 50 rpm
10. Turn the headlights off. ldle the engine for oneminute with heater fan switch at Hl and air condi-tioner on, then check the idle soeed.ldls speed should be:
810 t 50 rpm
lf the idle speed is not within specification, seeSymptom Chart on page 11-84.

\
I
'98 - 0O D16Y5 ongine with CvT
Adjust the idle speed using a Honda PGM Tester if pos-
sible. lf not, use the following procedure:
NOTE:
. Leave the IAC valve connected.
. Before s€tting the idle speed, check the following
rtems:- The MIL has not been reported on.
- lgnition timing
- Spark Plugs- Air clean€r
- PCV svstem
'1. Connect a tachometer.
2. Stan the engine. Hold the engine at 3,000 rpm w'th
no load (transmission in E or E] position) until the
radiator Jan comes on, then let it idle.
3. Check the idle speed under no-load conditions:
head lights, blower fan, rear defogger, radiator fan,
and air conditioner are not operatlng.
ldlo spaod ehould bo: 700 t 50 rpm
. lf the idle speed is within the specification, the
procedure is comPlete.
. lf the idle sDeed is out of specitication, 9o to step 4'
4. tf the idle speed is 810 1 50 rpm, this means the
EVAP system is purging the canister. To stop the
purging temporarily, raise the engine speed above
l,OO0 rgm with the accelsrator pedal. Slowly release
the pedal. and rscheck the idl€ speed.
. tf the idle speed is within the specificstion, the
Drocedure is comPlete.
. lf the idle sp€ed is out of spocification, go to step 5.
5. Disconnect th€ EVAP purgs control solenoid valve
2P connector.
EVAP PURGECONTROL
6. Remove the cap and turn the idle adiusting screw
1/2-turn clockwise or counterclockwlse
IDLE
7.After turning the idle adjusting screw 1/2-turn, check
the idl€ speed again. lf it is out of spec, turn the idle
adjusting screw 1/2-turn again.
NOTE: Do not turn the idle adjusting screw more
than 1/2-turn without checking the idle speed.
Turn the ignition switch OFF. Reconnect the EVAP
purge control solenoid valve 2P connector' then do
the ECM reset Procedure.
Start the engine. ldle the engine for one minute with
heater fan switch at Hl and air conditioner on, then
check the idle speed.
ldle spaed should be:
810 t 50 rpm (in El or E Posiiion)
lf the idle speed is not within specification, see
Svmptom Chart on Page 11-84.
9.
SOLENOID VALVE
11-223

\J
816A2 engine:
DEFLECTION10-12mmBla- 112inl
CABLE ADJUSTINGBRACKET NUT
t
lf deflection is not within specs' loosen the locknut'
turn the adjusting nut untilthe deflection is as speci-
fied, then retighten the locknut.
With the cable properly adiusted, check the thronle
valve to be sure it opens fully when you push the
accelerator pedal to the floor. Also check the throt-
tle valve to be sure it returns to the idle position
whenever you release the accelerator pedal'
LOCKNUT
lnstallation
Dl6Y5, Dr6Y8, D16Y, €ngine:
1. Open the throttle valve fully, then install the throttle
cable in the throttle linkage, and install the cable
housing in the cable bracket.
D16Y5, D16Y8 engins:
LOCKNUT
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.
Hold the cable sheath. removing all slack from the
caDle (cont'dl
11-245

Intake Air System
Throttle Cable (cont'dl
4. Set the locknut on the cable bracket. Adjust theadjusting nut so that its free play is O mm.
5. Bemove the cable sheath from the throttle bracket,reset the adjusting nut and tighten the locknut.
O16Y5, D16Y8 engino:
ADJUSTING NUT
9.8 N.m{1.0 kgl.m,1.2 tbt.ttl
DtGYT 6ngine:
11-246
816A2 engine:
1. Open the throttle valve fully, then install the throttlecable in the throttle linkage. and install the cablehousing in the cable bracket,
THROTTLE LINK
LOCKNUTADJUSTINGNUT
Start the engine. Hold the engine at 3.000 rpm withno load (in Park or neutral) until the radiator fancomes on, then let it idle.
Hold the throttle link to the throttle lever; thereshould be no clearance.
Hold the cable sheath, removing all slack from thecable.
Turn the adjusting nut untit it is 3 mm {1/8 in.) awayfrom the cable bracket,
LOCKNUT9.8 N.m(1.0 kgt m,7.2 tM.ttl
ADJUSTING NUT
Tighten the locknut. The cable deflection shouldnow be 10 - 12 mm l3/B - 1/2 in.). lf nor. seeInspection/Adjustment.
3 mm 11/8 in.)