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Wandering Idle / Excessive Smoke on Cold Start

openwater
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openwater Member

openwater

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'99 base - 71k miles. Two weeks ago the idle would not settle in at the usual 780 after a cold start. Wandered between 800 and 1000 in a random manor. Realized I had not been on the freeway in some time (I live a mile from work) and rarely got up to temperature for prolonged periods this winter. Went on a 40 mile loop at 80 mph or so but idle did not even out. It wandered less, but started to get rough when approaching the typical 780 rpm. Ran a tank with Techron injector cleaner with no change. No pending OBD codes. No loss of power. Noticed excessive white smoke on cold start Saturday. Monday - even more smoke then the idle started going crazy. Pulsing between 850 and 1200 over and over at about a second and a half interval.

Spark plugs changed 8k miles ago. New MAF - 5k miles. New 2nd air system plumbing 2k miles. New oil 2k miles.

Thanks in advance!

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Tool Pants Member

Tool Pants

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On the idle issue my guess is the idle stabilizer valve. On a non-egas there is a valve that moves to stablilize the idle. Over time carbon gets in this valve and it does not move freely. The valve is attached to the throttle body. You remove it and clean it with carb cleaner.

This is it on a non-egas 996.

post-4-1173891704_thumb.jpg

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openwater Member

openwater

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Has the oil seperator ever been replaced? The part has been updated a few times and can cause both problems.

I suspected the oil separator based on previous posts... didn't know it could have this effect on the idle. TP - Is there a gasket required for the re-install of the valve? Difficult to see from the photo. Thanks

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