Need some help, A8 issue

[RAUDIS6]

Hey Everyone,

My first step into the A8 forum. I have had many B5's and C5's. I am asking this one on behalf of the controller at my work. He has a gorgous 2004 A8L. Here is the issue. Not sure where to start. He will start the car, it will run for about 15 seconds, and choke out and die. Turn the key off, and then back on, same thing, will only stay running for 15-20 seconds. Seems electrical. He brought it to his Indy repair shop that he has been going to for years, and they can't figure it out. Any ideas befor he brings it to the dealership. Problem is they just like replacing things until it finally works.

Thanks in advance.

[AudiFan6482]

does it die immediately when you try to give it gas during the 15 seconds it runs?

[silverd2]

Check engine light on? If so, what are the codes?
A code reader is cheaper than ANY visit to a dealer.

Any work done recently? Battery died or disconnected recently?

[RAUDIS6]

NO recent work, no CEL, so not sure if any codes are stored, but I know the INDY shop has a VAGCOM, so I assumed that would be the first thing they would of checked, but can't be certain. It is not immediate upon giving gas. You can put it in drive, get up through about 2nd gear and it cuts off. Almost like something electrical or a sensor is cutting off the fuel. It acts like it chokes out, or ran out of gas. We swapped in a fuel pump that we knew was working, same thing. Very perplexed.

Thanks for the responses so far.

[HIstateS8]

Any other indicator lights on? Without knowing the codes it's all guess work.

[silverd2]

NO recent work, no CEL, so not sure if any codes are stored, but I know the INDY shop has a VAGCOM, so I assumed that would be the first thing they would of checked, but can't be certain. It is not immediate upon giving gas. You can put it in drive, get up through about 2nd gear and it cuts off. Almost like something electrical or a sensor is cutting off the fuel. It acts like it chokes out, or ran out of gas. We swapped in a fuel pump that we knew was working, same thing. Very perplexed.

Thanks for the responses so far.

About the only thing failing that does NOT (why? ...I dunno) throw a code, is the fuel pump...doesn't sound like typical symptoms of a failed pump, but not out of the question. Less likely would be a clogged fuel filter ...extremely rare and unlikely on these cars, unless you got a tank of REALLY contaminated (sediment) gas.

Mechanic needs to have a fuel pressure gauge installed in-line during the failure...this would determine if it's really starved for gas or being "shut down" from another source.

Just guessing, but if not the pump, a bad fuel pump relay cutting power...probably wouldn't throw a code by itself, but being starved for gas repeatedly should at least throw a "lean condition" code.

The symptoms sound more like a throttle body, MAF or other problem (immobilizer...not likely)that "should" throw a code ...and a CEL.

Hard to say without being there.

[Vinchenzo51]

Tried the basics? Clean the maf, check plug gaps or for fouled plugs, replace fuel filter, check for pressure at the rail. Does this car have ICMs or coil packs?

Again, without any leads, like the others have said, just taking shots in the dark.

[RAUDIS6]

Thanks guys. I am going to see the car first hand this weekend. The MAF was replaced, I know that. I will bring my VAGCOM and see if there are any stored codes.

Thanks again!!!

[s4master1]

sounds to me one of the fuel pumps has failed, usually the driver's side is the one that fails first.
check pressure output individually one at a time and see if any difference.

[silverd2]

Tried the basics? Clean the maf, check plug gaps or for fouled plugs, replace fuel filter, check for pressure at the rail. Does this car have ICMs or coil packs?

Again, without any leads, like the others have said, just taking shots in the dark.

All A8's have coil packs (97 on), starting with 2000 models with 40V motor the ignition output stages are built into the individual coil packs...so no ICM's from 2000 on...signals come directly from ECM.

[RAUDIS6]

OK here is an update: This guys Indy must be crazy. I hooked it up to the VAG and got 4 codes. P1128, P1138, P2234, P2231. Since being at the shop to figure out wht the car chokes out and dies, fuel has been drained and replaced with Chevron 91 octane (best he can find in California) and AMS sensor replaced. Any ideas with those codes.

Thanks

[boiseauctioneer]

I pulled the P2234 code today, any more info on this? That was the only code I pulled

[AudiA6Biturbo]

what s4master1 said one of the fuel pumps has failed. Both pumps run when starting the car giving you enough fuel pressure to last 15-20 seconds. Put a fuel pressure gauge on it to verify..

[BASARAB]

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