Idle surges when engine is warm, low engine temp or IAC or FITV

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Mar 23, 2018

Wilco

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Idle surges when engine is warm, low engine temp or IAC or FITV

I have a 1995 1.5L Civic Dx 4 door. The car starts up fine, but when the engine warms up the idle surges and drops repeatedly. I read on some threads that it could be the IACV, or the FITV, or leaky vacuum hoses, or air bubble in coolant. I checked the first three, and did not find any problems; I cleaned out the IACV, but the idle surging/dropping continues. I have noticed that the engine temperature is lower than normal, about 1/3 of the way on the gauge, or just below the 1/2-way mark. I wonder if this is causig the idle? How can I check the coolant temperature sensor with a volt meter? Also, there are no check engine lights. Unfortunately, I do not have a shop manual, so I am getting all my repair information from online. Thanks.

Last edited by Wilco; Mar 23, 2018 at 12:57 PM. Reason: add

Mar 23, 2018

ezone

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Re: Idle surges when engine is warm, low engine temp or IAC or FITV

Quote:

How can I check the coolant temperature sensor with a volt meter?

Make sure your radiator fan works first.....

Let it sit and run until the radiator fan comes on....Coolant temp should be about 195-200F or so when the fan kicks on.

See where your gauge is at and see if the idle is stable at that time.