Prin

Ok, I recently did more work to my ride. I did the whole forged rotating assembly as well as added a FAST 92/92 combo. Well, now, the car will not hold a cold idle. I replaced the IAC motor and still nothing. It will go dead if you let off the pedal. Once it warms up, I can hear a huge vacuum take over and the car then idles on its own. What do you guys think?

teke184

iTrader: (5)

the vacuum sound is likely just the added noise from the FAST intake.

i noticed it as soon as i put mine on....sounds like a vac leak...but it doesn't appear to have one.

Prin

Yeah, I think that is what it is. But, what about the cold idle?

youguessit

check to make sure the map sensor on the back of the manifold is not leaking vacuum. This could give it a hard to start till it warms up.

ramair21

iTrader: (2)

I just replaced my TB with a S3 polished TB. After i installed it i could hear my intake suck so much air, i thought it was also a vacuum leak. I had to use HPtuners to tune the Idle Airflow and IAC steps for start up since i was sucking so much air. I also installed the LS6 intake after the TB. You might be in the same boat i was in

kinglt-1

iTrader: (26)

Has it been tuned?

Prin

Yes, it has been tuned...

teke184

iTrader: (5)

was the cold start tuned?

or just WOT and/or driveability.

mine has been tuned twice, and even with a part throttle tune, it surges all over the place at cold start. soon as it hits closed loop it smoothes out in seconds and holds steady at ~900rpm

Prin

The cold start has been tuned. That is what puzzles me.