Manual transmission on my car so it's easy to notice a slightly higher Idle. Maybe 100-200 Rpm increase.

The last few days I notice that sometimes at a Stop sign the idle is slightly higher then it should be. If I wait, it sometimes will creap down to where it belongs, sometimes not.

The other evening, I switched out the Idle Control Valve for another one that is functioning. I gave the Throttle body a quick cleaning..it was clean anyway but I took some Carb cleaner on a Rag and ran it around the 'seating' area of the inner butterfly. Didn't help.

I ran the car..it was still idling high, I checked and the linkage if fine, very free moving and it moves to a fully rest position. So the linkage isn't the issue.

Can a lazy O2 sensor cause the engine to idle slightly higher then normal? The fact that this Idle problem comes and goes withion the same drive leads me away from a Vacuum leak.
I haven't thrown a meter on the sensor, and I haven't sprayed around some Vacuum drawing areas yet . Just thought I'd ask about the O2 sensor.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

is it only when it is cold? When you tap the gas does it go back down to normal?

Welcome to te Brickboard



It does it warm or cold.


No it doesn't 'kickdown' like a Carburated car.

I t was a small crack in a vacuum hose that overlooked when I gave it a quick look during the week.


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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

Vacuum leak? Seems more likely.

Tiny Crack in the Small hose on the Intake leading to the Heater/defroster stuff. I looked at it in the dark garage the other night and didn't see it.

Of course I was under a Time limit... Wanted to do the idle Control valve/ flame trap/check Throttle body... but the wife stuck her head in the garage and said "20 minutes 'til dinner" so I wasn't looking carefully.

Gave it a basic tuneup this morning and saw the vacuum issue. Idles back down where it belongs

Thanks
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

My bet would be on a vacuum leak or an idle position switch on the TB that needs adjusted. A slow O2 sensor typically affects gas mileage and overall driveablity.

jorrell
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92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!

That was my thought on the O2 sensor. They usually cause a rich condition but no necesarraly a higher idle. that's why I was asking. Oh, I did check the Positioning switch, it's set OK. The neighbor gets a kick out of me using a stethescope on a car engine.

Actually, the switch is just just set for the slightest movement of the accelerator.. maybe, for giggles, I'll move it a bit.

Thanks Jorrell
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm