High, hanging idle issue

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May 23, 2010 | 08:13 PM

98noscamaross

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From: Durant, Ok.

High, hanging idle issue

I have an 01 SS w/ a truck manifold kit. My specs are a mpt76 q-trim, stock 6.0l w/ turbo cam. I went to the track yesterday and on the way back I noticed at the red lights my car was idleing about 200 rpm higher then normal, after making it back it started to let the rpms hang when I let off to shift. Now, with the car sitting at idle the slightest touch of the throttle causes it to raise the rpms over 1500rpm more, and when it does this it hangs there for several seconds the returns to idle. Other than this problem the car runs fine and doesn't miss. I tried changing out the TPS and the IAC but no go. I also pulled the intake off to check there but it still does it. By the way my car is speed density tuned. I would really appreciate some ideas or help trying to track down the cause of this problem. Thanks in advance.

May 23, 2010 | 09:22 PM

black98ws6ta

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From: louisville,ky

Check good for vaccum leaks?

May 23, 2010 | 09:26 PM

Bird-Of-Prey

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From: Lebanon, OH

What TB are you running? If it's a FAST 90mm older version, it's a known problem.

May 24, 2010 | 05:25 AM

98noscamaross

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From: Durant, Ok.

Yes, I have checked for vacuum leaks, but I have yet to find any. I even went crazy with carb cleaner, and I still didn't find anything. However, I can hear a faint high-pitch whistle that I can't seem to find.

I am using a BBK 80mm tb.

May 24, 2010 | 05:49 PM

code4

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mine does this because of the way i ran my pcv system. it gets extra air by bypassing the iac. i haven't bothered trying to tune it out yet. i'm auto so it doesn't bother me much.

May 24, 2010 | 06:06 PM

RyeLou

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Quote:

Originally Posted by code4

mine does this because of the way i ran my pcv system. it gets extra air by bypassing the iac. i haven't bothered trying to tune it out yet. i'm auto so it doesn't bother me much.

I have a similar issue, but mine is enough to actually push the front tires if you're on anything other than solid ground. Mine will fix itself by turning the car off and back on though. I'll work on actually correcting the issue later, ha.

May 24, 2010 | 10:02 PM

pontiac455cars

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From: millbrook,al

my car was doing the same,I routed pcv system to a catch can.Also put a return spring on the throttle body.I dont know which fixed it but i drove it all day sunday without any symptoms.