Honda Civic ECU issue - Honda-Acura.net

vindice · 02-10-05, 11:22 AM

My car has recently started to idle high to low whenever stopped. My mechanic thinks it's a computer problem and has directed me to go to the dealer.

Do I have any other options than letting a dealer assess the problem? What would one guess would be the cost for a dealer fixing this issue?

Any help/advice/info appreciated.

Thanks,
Patrick

(about 115,000 miles - 1994 Honda Civic CX)

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JimBlake · 02-10-05, 01:39 PM

This is pretty common, & it's not usually the computer.

1 - First look for vacuum leaks. Bad hoses? Disconnected?
2 - Then look for air pockets in the cooling system. (Change antifreeze lately?)
3 - If you wanna DIY, then clean out the IACV & FITV.

miahmouse · 02-11-05, 03:09 PM

Quote:

Originally Posted by JimBlake

This is pretty common, & it's not usually the computer.

1 - First look for vacuum leaks. Bad hoses? Disconnected?
2 - Then look for air pockets in the cooling system. (Change antifreeze lately?)
3 - If you wanna DIY, then clean out the IACV & FITV.

I'll throw in a vote for #'s 1 and 3 with emphasis on vacuum leaks and IACV

vindice · 02-12-05, 03:43 PM

Thanks for the tips!

Sorry, but what is IACV and FITV?

To provide more detail...the hi-lo idling started within 5 minutes after the car had to be jumpstarted. There wasn't a problem before the jumpstart.

teg92 · 02-12-05, 04:02 PM

IACV is the "Idle Air Control Valve" On the intergra's its loctated on the back of the Intake Manifold. What kind of car do you have?

vindice · 02-12-05, 05:05 PM

Thanks for the reply. It's a '94 Honda Civic CX. This only started after it the battery had run down (gf left the lights on) and was jumpstarted. It was outside in rather cold weather at the time as well (20 degrees I believe).

No idle problems while driving. It only fluctuates when it is stopped. I would say it idles from a normal level for the car to a very low level. Does not idle high.

JimBlake · 02-14-05, 12:50 PM

The IACV is #17, it's on the back of the intake manifold, against the firewall.
The FITV is #13, it's on the underside of the throttle body.

Either one or both can be dirty, sticky, whatever. I think there's coolant in both, so be prepared for that when you take them off. Hasn't happened to me, but I guess sometimes the guts of the FITV can come loose causing a surging idle.

Still, don't forget to look for vacuum leaks.

background info...
The ECU controls a steady idle by telling the IACV to open & close as you turn different loads on & off. The fast-idle thermo-vavle (FITV) is supposed to let some air past the throttle to increase idle speed when the engine's cold. The FITV is supposed to stay completely closed once it's warmed up.

02-10-05, 01:39 PM	#2
JimBlake Senior Member Join Date: Jan 2003 Posts: 1,994	This is pretty common, & it's not usually the computer. 1 - First look for vacuum leaks. Bad hoses? Disconnected? 2 - Then look for air pockets in the cooling system. (Change antifreeze lately?) 3 - If you wanna DIY, then clean out the IACV & FITV. __________________ JimBlake '03 Accord, '07 Civic '01 Saab 9³, '05 9²x

02-14-05, 12:50 PM	#7
JimBlake Senior Member Join Date: Jan 2003 Posts: 1,994	The IACV is #17, it's on the back of the intake manifold, against the firewall. The FITV is #13, it's on the underside of the throttle body. Either one or both can be dirty, sticky, whatever. I think there's coolant in both, so be prepared for that when you take them off. Hasn't happened to me, but I guess sometimes the guts of the FITV can come loose causing a surging idle. Still, don't forget to look for vacuum leaks. background info... The ECU controls a steady idle by telling the IACV to open & close as you turn different loads on & off. The fast-idle thermo-vavle (FITV) is supposed to let some air past the throttle to increase idle speed when the engine's cold. The FITV is supposed to stay completely closed once it's warmed up. __________________ JimBlake '03 Accord, '07 Civic '01 Saab 9³, '05 9²x

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02-12-05, 03:43 PM	#4
vindice Registered User Join Date: Feb 2005 Posts: 4	Thanks for the tips! Sorry, but what is IACV and FITV? To provide more detail...the hi-lo idling started within 5 minutes after the car had to be jumpstarted. There wasn't a problem before the jumpstart.

02-12-05, 04:02 PM	#5
teg92 WHAT OK YEAH! Join Date: Sep 2003 Location: overthere Posts: 5,567	IACV is the "Idle Air Control Valve" On the intergra's its loctated on the back of the Intake Manifold. What kind of car do you have?

02-12-05, 05:05 PM	#6
vindice Registered User Join Date: Feb 2005 Posts: 4	Thanks for the reply. It's a '94 Honda Civic CX. This only started after it the battery had run down (gf left the lights on) and was jumpstarted. It was outside in rather cold weather at the time as well (20 degrees I believe). No idle problems while driving. It only fluctuates when it is stopped. I would say it idles from a normal level for the car to a very low level. Does not idle high.