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View Full Version : Strange Idle issue (NOT the typical hunting idle)



androo
25-08-2014, 11:18 AM
Hi guys,

I have a strange idle issue and was hoping someone here might be able to help me. Other than this idle issue, the car appears to be running perfectly fine. Engine is smooth and there are no strange noises to speak of. The car is a Honda CRX 1996 (OBD1).

This is not your typical hunting, bouncing idle issue, high idle or rough idle. The car appears to runs perfectly but the idle seems to creep slowly to around 1,000rpm and stays there after about 30-40 minutes.

A rough timeline from start up to help explain the issue:


Cold start: Steady around 1600rpm and drops slowly. I have no issues with this.

10-15 minutes: The car idles at 700-750rpm nice and steady once the engine is warm.

20 minutes: My idle has slowly risen to 850rpm

30-40 minutes: My idle sits at approximately 1000rpm (steady - it does not bounce or hunt at all).

Up to 2 hours later: Car is still idling at 1000rpm. There is no change.


There does not seem to be any negative impact other than a slightly decreased fuel economy. I haven't driven longer than 2 hours since the problem started to occur but I have no reason to believe it would climb any further.

I'm out of ideas and don't know how to proceed so if anyone has any suggestions, please let me know!

Thanks all,
Andrew

bennjamin
25-08-2014, 11:33 AM
Brake booster issue? Remember it is connected to your inlet manifold and can alter the idle. Check the one way valve on the line

ECU-MAN
25-08-2014, 01:13 PM
could also be the FICV