Running Fault

[mrpat]

Hi, I've got a strange running issue with a 3B engine. It will starts and run good, idles good, and drives good. The problem arises if it's left to idle for more than about 20 seconds.

The exhaust note changes, and if you touch the throttle very lightly the revs surge up and down, and engine note changes as if it's under load. Turn of and restart and it's back to normal again until it idles for more than about 20 seconds

Fault codes stored is 00533 idle speed adaption limit exceed.

So far I've pressure tested from the maf to just over 1 bar, and gone over everything with soapy water in a spray. Replaced the hose to the throttle body, injector seat and seals and reposition a few hose clips. Pressure tested again with soapy water. No more leaks.

TPS is adjusted correctly all the PCV system is new, hoses, valves etc. Idle valve seems to function correctly.

Any help would be appreciated, I know diagnosis is difficult over a form

Thanks
Martin

[UrS4boy]

N71 ISV info and Vacuum Line Info

Fault codes stored is 00533 idle speed adaption limit exceed.... Idle valve seems to function correctly. Any help would be appreciated, I know diagnosis is difficult over a forUm. Thanks. Martin

You might still have a vacuum leak. This link is too AAN info but it will be similar for your 3B (note the hyperlinks inside the link):

http://forums.quattroworld.com/s4s6/msgs/139863.phtml

I'd also check the and really confirm that the N71 ISV is working properly and isn't gummed up and sticky:

http://forums.quattroworld.com/s4s6/msgs/21853.phtml

[mrpat]

I've gone over several times checked all hoses pressurised to over a bar, no leaks

I've noticed I have a ADU airmass meter will this cause any running faults as my 3B is standard.

Thanks

[twoqu]

If you have disturbed the PCV plumbing see post 10 down:

http://www.s2forum.com/forum/showthread.php?t=61946&highlight=00533