Rough idle on cold start - no brakes

[905084]

So I'm just starting to love my RS when it goes 5150....again. Cold start with rough idle, no power brakes. Haven't VAGed yet but I'm thinking vacuum leak. Any ideas? It's ok after 3-4 minutes of running. SAI is disconnected.

Thanks all.

[ben916]

yep, that is the route i would pursue - no vacuum

[Justin9212]

Check the line going to the booster. Only line big enough to lose power brakes.

[AUDI5000CSTQ]

Use the search. It is the vacuum connection under the intake.
Others have posted diagrams and part numbers

[Amar]

I'm sorry, but why is this thread five freaking stars? :S

[4everRS]

I'm sorry, but why is this thread five freaking stars? :S

Cause there's some mouth breather that keeps rating almost all of them.

[4everRS]

Ya, Unfortunatly my guess is under the intake. No fun, but better than an engine pull.

[905084]

Thanks, motor has to come out to do the trans at some point. Wondering why only when cold though. Every time it get something working something else breaks, arrrgghhh...

[Brav]

Yea, likely it was the Suction Jet Pump.. or if you are more lucky, vacuum hose somewhere connecting to the brake cylinder.

here is my saga with it.. see if the symptoms match yours. also half way through is my somewhat of a DIY for fixing it.. if you are so brave.

http://mobile.jvc.com/product.jsp?modelId=MODL029037&pathId=139&page=3

[NSU RS6]

I was looking at my daughter's 2002 Volvo S60 the other day.......it has a vacuum pump just like the one in our cars. Except is so unbelievably accessable, I almost took a picture of it to post here. It is right behind the radiator, up high, with plenty of room around it. 5 minute fix max. Of course, it will probably never need fixing, because it sits in a nice cool area of the engine compartment. Audi decided to put the RS6 pump in a place where it bakes, and then virtually locked the door to the oven.

[kday]

If you mean those venturi type pumps, Audi has been known to make them more accessible. It's easy to get to on the 12 valve V6 too. (Though the C4 A6 might be the roomiest Audi engine bay ever -- built to hold both a longer I5 and a wider V8, with the V6 it has room in all directions.)

[ThrillHouse]

Has anyone relocated the Suction Jet pump? Seems like it may be a good idea if for any reason the engine is out of the car and/or the intake is off

[Brav]

Has anyone relocated the Suction Jet pump? Seems like it may be a good idea if for any reason the engine is out of the car and/or the intake is off

Possible, but a bitch to re-run all of the tubing and hard lines sandwiched between the manifold and block. May create more problems than its worth.

http://i49.photobucket.com/albums/f282/ckreidel/Audi%20RS6/IMAG1359.jpg

http://i49.photobucket.com/albums/f282/ckreidel/Audi%20RS6/IMAG1357.jpg

Whomever designed this aspect of the car had a sick sense of humor. Probably so pissed off at having to figure out how to stuff a TTV8 into a 6-pot designed car..