1994 Acura Integra wildly fluctuating idle in cool and cold

BARRYSHATZ

MEMBER
1994 ACURA INTEGRA
4 CYL
FWD
AUTOMATIC
191,000 MILES

Started over a year ago. When the weather cools the idle rises and falls wildly. At traffic lights I have to put it in neutral to be able to stop safely.
First I removed the idle control and cleaned it thoroughly thru the screen. When that didn't work I replaced it with a used idle control. When that didn't work I removed the large hose going back from the air filter and thoroughly cleaned the butterfly. Still no change. When I start the car in the morning the idle screams so high you would think the car is about to explode.
What do I do?

2 Replies

KHLOW2008

MECHANIC
41,815 POSTS

Hi barryshatz,

At the bottom of the throttle body there is a Fast Idle Thermal valve. Remove the cap and check if the valve has worked itself off. The valve should be fully closed when the engine is at operating temperature.

To test the problem, remove the air intake hose and with engine running, close the lower port inside the throttle body and if the idling speed drops to normal, the FITV is faulty.

Check for clogged coolant hoses to the IAC and FITV.

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Sunday, January 10th, 2010 AT 8:11 AM

BARRYSHATZ

MEMBER
3 POSTS

Boy, you guys are good! I got suggestions from other sites such as RepairPal to replace the coolant temperature sensor, replace the idle air control, monitor the coolant level, etc. I did what I could to control cost. Nothing worked. I couldn't find the fast idle thermal valve and eventually had to take the car to the dealer.
The repair wasn't cheap, but was necessary. They showed me a totally clogged fast idle thermal valve and now the car runs normally. Too bad I couldn't have found the valve myself but still I appreciate your expertise and excellent answer.

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Thursday, January 27th, 2011 AT 9:06 PM