Well here's the whole situation ^^ S5 turbo NO EMISSIONS.

I just rebuilt the turbo on my s5, did the TB Mod on the throttle body removing the butterflies and the AWS. Cleaned all greased all return springs on the TB. I replaced all vac lines too and from the UIM and reset the TPS back into range. New gasket for UIM.

When i start the car it will idle normal and very smooth at around 1,500k because of the TB MOD.
After the car warms up and i get off any boost the idle will kick all the way up to 2,000-3,500 and will surge slowly but not constantly. Its strange because when this happens i can push the throttle down and it will stay stuck in that pos sometimes. Ive checked the TB and made sure there was nothing keeping the throttle flaps from closing. They Close Fast and Smooth. I would have to tap on the throttle to get it to close the flaps in the TB sometimes. I know it might sound like a frayed throttle cable or something but the throttle cable is only a few months old. Any Ideas or suggestions would be greatly appreciated.


Around this time is usually when it will start to free-rev.. almost like im getting a massive amount of unmeasured air into the engine somewhere. This has to be a vac leak somewhere but ive looked over everything so many times i just cant figure out where it could be coming from. As for the pre boost hesitation, i think its from not having the pill for the boost sensor. Just a guess. I have a new fuel filter to put on.. which could also be the problem.


Note*
These problem only seem to occur when the car is fully warm from driving or after any boost.

 

bump

 

I remember a friend who had the same problem, he found there was a massive leak on the throttle body. no leaks coming there?(I guess doulbe check) the other thing I can think of is the BAC valve, do you still have that on the motor?