Stalling.....

[A8Mark]

Since ive had my car back from Audi stealers its been stalling when hot(sometimes).

If i sit in the car with the engine running for a while it will suddenly cut the rev's down to around 500 rpm,

then when u pull away its runs ok until you come to a junction then the engine stalls and all hell breaks loose.

I nearly ran into a parked car as i lost all power steering etc...

Any ideas where to start looking or do u think it needs a tune up or something?(runs as sweet as a nut all the rest of the time).

Any input helpful...

A8Mark....

[PaulW]

Me and my friend just fixed the same problem on his car last weekend.

Take off the beauty covers on the engine and check the fit and tightness of the clamps on the hoses from the airbox to the throttle position indicator.

His were loose, they can also fold under when you reinstall them, so make sure they are properly seated all the way around.

HTH!

Here's all the pictures and how to do it.....

[cruiser647]

Mine has done this AND is still doing it. Not all the time though.

Most of the time it is when I slow down from a cruise on the motorway, and I am coming down the slip-road.

To help cure it, I removed the air hoses TO the engine, and cleaned out the throttle housing with Surgical Spirit and kitchen towels - that helped ALOT! Also, put in some MILLERS petrol injector cleaner (Redex is POOH).

Clean out the air filter (or replace with a K&N replacement job from eBay). Clean the MAF element carefully, with the spirit. Maybe even changing the spark plugs for the Platinums in PW link OR the normal Bosch ones. (Accept no substitute plugs other than Bosch).

Hope this will help!

ALSO, if you can get a hold of a VAG-Com, and plug it in under the front ashtray, you can get the codes and see what is happening.

Good luck!

[fenn]

I had this with mine,and eventually rang Gareth at the Audi U.K.designated A8 service centre,on 0800-699888-mine had to have the e.c.u. and throttle body changed(not cheap,I admit),but I got the distinct impression that Audi are not unaware of the problem,and i wasn't the first to complain-when I banged on about how dangerous it was etc.,they agreed to loan me a nice shiny new A8 whilst mine was being repaired-they didnt pay for the repairs though!-might be worth giving him a call.

[Ska]

OK forget the engine upgrades it looks like its a case of . My car has developed the stalling symptoms described in this post! AAAARRRRRHHH!!!

It happened over night, I was playing around with the wiper mech. This revealed a broken bush which caused a hell of a lot of play. No probs. Get a new one and fix it. However, this morning got up for my 90mile commute to work and the stalling happened when I came off the motorway and slowed at a junction; then whack, engine cuts out no power steering and a large flat bed truck bearing down on me! Ever since its been cutting out on a few occasions and threatening to on others (hunting then returning to about 500rpm)

Anyway I’ve opened the air flow pipes and every thing looked tight and secure, the car is due for a service so the filter was dirty but the insides of the pipes and box were fine and dry! I’m going to replace it and the plugs in the morning to eliminate these as the cause or hopefully to cure it!

What was a bit puzzling was that if I turned the A/C compressor on it wouldn’t stall or hunt and would be fine (something to do with engine load and increased revs to compensate for compressor?).

What terrifies me is if it’s the ECU. Is the dealer the only option or can I source a cheaper part from somewhere else, better yet get it installed; how much is it likely to be? Is there anything I’ve missed?

I would appreciate your thoughts and opinions

[PaulW]

You say that when the AC compressor is on, it doesn't stall, what happens is that the idle stablization valve gets a larger duty cycle of 12 VDC (i.e. more like 6 VDC versus 4 or 5 VDC average) and allows more air into the engine so idle speed can be maintained under higher load.

You can remove the ISV and clean it, sometimes they get junked up carbon stuff and mechanically don't operate very well any longer even though they have the correct voltage to them.

And just make sure all your connections on the air intake are tight, which it sounds like you already have.

Good luck!

pw

[Ska]

thanks for the reply Paul, where is this valve located and any tell tale signs of what it should look like?

Thanks again

[PaulW]

If you look at this post, you'll see a picture of it.

You would have to remove it, then clean it out with brake cleaner (just keep soaking it and let the carbon stuff fall out) and then put it back on again.

Many of the older Audi's had this problem over and over again....not too many A8's have had the rough idle/stalling so we are still working out what it really is.

pw

[Ska]

thanks again Paul , the ISV is more or less in the same position for 2.8 V6 as the 4.2 V8 and seems to be inline with the air supply tube. Double checked with the dealer it cost about £300! but I'll give it a clean first. Mind you I gave the car a service replacing the air filter plugs and its stopped cutting out , though it does hunt around idle speed occasionaly, hence the cleaning of the ISV seems mandatory (I'll post some pics.)