2001 S4 climbing and droping RPM when idle.

[RICO85]

2001 (B5) AUDI S4

When i turn on my car the RPM's fluctuate between 700 and 1500. And there seems to be a popping sound coming from the engine bay as well. The car is fine when I'm driving it, but when i come to a complete stop the RPM's just start to drop, and climb sporadically. There is no check engine light, and no codes. I have replaced the spark plugs and the air filter, but the car still does the same thing every time i turn it on. I have read other threads with people having the same issues with the RPM's, but no one has the popping in the engine like i do. Any help will be gratefully appreciated.

Thanks!

[BlkdoutS4]

have you pressure tested for leaks?

[RICO85]

not yet, but thinking of doing it tomorrow.

[BlkdoutS4]

not yet, but thinking of doing it tomorrow.

i would do that first, then go from there. almost sounds like you could have a big leak at the TBB

[mk2 16v turbo]

Definitely a big vacuum leak.

[RICO85]

Thanks! will definitely have to check that out. I plan on replacing the TBB with the APR Bi-
pipe i just got in the mail. And hopefully a pressure test will tell me what I have to fix.

[iBeast]

did you ever solve this my are is doing the same thing

[RICO85]

did you ever solve this my are is doing the same thing

Yes, I have not been in the B5 forums since I got a CC. There was a vacuum leak in the pcv valve. The valve had a crack in it, and caused the o-ring that held it in to the manifold to fall off. I replaces the pcv valve, and the problem has not come back. I also replaced the TBB, and both diverted valves with APR bi-pipe and 710N's. Hope that helps. This also happened to my friends S4 a couple months ago, he just put silicone on the pcv valve and called it a day. As far as I know the problem hasn't come back on his car either.

[iBeast]

thx you. Ima check for a vacation leak tomarrow

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[BlkdoutS4]

thx you. Ima check for a vacation leak tomarrow

Sent from my LG-P999 using Tapatalk 2

Vacation leak? Nice...

[iBeast]

lol my stupid phone likes to autocorrect everything