high idle

[camaro_fred]

I've got a problem that came slowly on my car (99 V6) : when the car is cold, after accelerating, each time I release the throttle, engine RPM goes down to 1200 RPM, holds it 4-5 seconds then goes back to 700-800 RPM
If I don't accelerate at all after start, the car will heat slowly and RPM will never go over 800 RPM.
Before that, my idle was always 700-800 RPM even when engine was cold. It happens only in winter, and it doesn't make it when engine is hot.
I've checked my PCV valve and it's like new.
Seems there's no IAC valve because I have electronic throttle. SES light off. No leaks from air filter to throttle body.
When car is outside for several hours and it's cold, I've noticed a weird sound under the hood, like air being sucked or metal shaft spinning without oil (whistle). Could that be a leak from the intake manifold?

My car has 20 000 miles on the clock, Dynomax super turbo and free ram air mod.

Any help appreciated,

Thanks,

Fred

[camaro_fred]

Anyone ?

Fred

[Turbo V6 Camaro]

what oil you using? i always used 5w30 in the winter cuase its thiner and don't sludge as bad

im not sure why the car idle high like that, you could have a leak the car will always idle a bit higher till it warms up

[Little G]

mine does it too. It's in the code and goes back to normal when the coolant is about 170

[KBeezy]

Its to compensate for the colder denser air if I remember correctly. Thats why you **NEED** to let your car warm up in the winter before you drive it!

[00firebird]

that sounds logical to me, where is the problem?

[camaro_fred]

Thanks for the answers.

viper04af : my oil is 5W40 Shell helix ultra (synthetic)

kbeezy : I thought the PCM was smart enough to keep a low idle with a cold engine (that's one advantage against carburettors)? And it does that only 4-5 seconds after releasing the throttle; if it was to compensate for cold air, idle would be always 1200 RPM until the engine has warmed up?

00firebird : the car didn't do that when I got it first (bought it new in 2000); it was more 800-900 RPM at full cold than 1200 RPM. The problem is, at 1200 RPM it "pushes" the car when releasing the throttle, not great on snow ! (I've got an A4 trans)

I've had another idea : could the electronic throttle have problems returning in the "close" position after an acceleration? I've never cleaned the throttle body til now, is it hard to do?

Fred

[1DangerousV6]

Originally posted by KBeezy:
Its to compensate for the colder denser air if I remember correctly. Thats why you **NEED** to let your car warm up in the winter before you drive it!

yup..i always do this..and if its cold enough it will sit there and idle slighty higher (with the exhaust being louder) until it warms up