Cleardonkey

Hello, I'm the owner of a 2002 2.7L Twin Turboed Audi Allroad. It is at 150,000 miles and an incredibly clean car. I bought it in November, and since buying it, a surprising issue has revealed itself.

About an hour into driving, the car will just shut off, sometimes around a turn, sometimes while stopping, sometimes going straight. I pull it to the side of the road, put it in park, and turn it right back on. It may or may not shut off one more time, but then it is perfectly fine. I have made five, 10 hour trips in this car, and it does the same thing every time.

Originally I thought it was something with the terminals and leads to the battery, which I tightened and threadlocked. Didn't solve the problem. I can't find a single bit of advice anywhere for anything like this. What could it possibly be, or is this car just cursed?

5v/cyl

You need to check for codes with Vag-Com. Even though the CEL may not be on, it doesn't mean that there isn't a code pointing to the problem. These cars are very sophisticated and have numerous modules monitoring the systems which can detect the problems everywhere when scanned correctly.

When the car shuts off does it sputter then die, lose power then die, or just shut off with no warning? Is everything else still working when it shuts off? Also what is the fuel level when it seems to shut off?

Cleardonkey

The only codes that have been pulled have had to do with the torque converter, but there was absolutely no codes when this started, other than the occasional code "System Too Lean" which has been resolved since then.

I would say it loses power and then dies. The fuel level varies, it has been pretty much full, half tank, whatever. The battery warning light pops on, which lead me to believe it was something to do with the battery, but there is no reason why it would do it once and then be fine for the next 8 hours of driving. The only consistent thing with this car is that it does it about an hour in driving, and the battery light pops on.

amiram

The main Switch?

PaperToast

at 150k, its prolly the alternator
thats when mine gave up
go get a load test done and that will tell for sure whats bad

5v/cyl

Damn, I'm on serious borrowed time! Still original alternator at 205k, but have noticed my voltmeter not holding at 14v under higher electrical demands, even at higher rpms. Maybe it's finally on its way out.

Curious though as how a failed alternator would cause engine to suddenly stall in the case of the OP? In theory the batt would run the vehicle for some time by itself with no charging from the alt.

I'm leaning toward a possible electrical ground issue or maybe fuel pump issue. Ever since I changed my fuel pump I can't go below 3/8 tank and drive for extended periods on the highway. Pump overheats and temporarily cuts out. Apparently is a common VW/Audi issue with replacement pumps according to Google search. That's why I asked the OP if it was at a certain fuel level, but his seems random conditions.

Cleardonkey

I'm actually starting to think that one of the electrical grounds isn't attached all that great. It broke it's pattern in the past couple of weeks. It shut off after 8 hours of driving in a really rough patch of road. When I was coming back through the next day, over the same spot it turned off twice.

Cleardonkey

I really don't think it's the alternator. My car previous to this one had a bad alternator, and all that did was slowly dim the lights and shut off. There was no turning back on with that car until a new battery was put in after the alternator no longer could charge the original battery.

I really don't think it has to do with the fuel pump, as it does do it randomly.

At this point, I'm willing to put money on an electrical ground issue. That's what I thought it was until it was showing it's pattern, which just turned out to be a coincidence.

Oh, and this is a her

John535is

hey Cleardonkey - Have you found the answer?
If not, you want to try something totally out of the box? It kind of relates to your electrical ground theory.

Replace the brake light switch. This may sound stupid (I've been called worse!) but the logic I am using is I had a problem starting my allroad and it turned out to be the brake light switch. If I got in the car and just turned the key it started. If I got in the car and put my foot on the brake before turning the key, it would not start.

So if you are totally out of ideas and no one can offer a solution, the brake light switch is cheap, (even from the dealer) you can change it yourself in about 5 minutes, worst case you have a new brake light switch which for a 2002 model is probably due anyway. I have already had to replace mine (2004) & my sons A4 (2005) so if yours is original then its due anyway. The new ones are constructed stronger than the originals, the only trick is don't be tempted to push the switch in when you get it out of the box. the switch is self limiting, so once you push it in, it will not come all the way out again. There are write ups on this site how to install them (by me and others).

grat

I'm thinking it might be the fuel pump. The fuel system is a high pressure system and the pump runs all the time. When it stops the car will suddenly die. So a loose connection on the fuel pump may be the culprit and would probably have the symptoms you are describing. Downside is that the connections to the pump with the exception of the wiring harness connector are inside the fuel tank. The pump is accessed under the right side rear seat (bottom). This tread will give you an idea of the connections/location: https://www.audiworld.com/forums/a6-...nyone-1715278/ with the mileage on your allroad a fuel pump/filter might be in order anyway. Do you have any records on the car to know when it was last changed?

edit: one other thought occurred, the crankshaft position sensor ties in to the fuel system. If it faults could cause similar results but I would think there would be CELs and/or other symptoms.
fj..