trillypop

Hey guys, looking for some guidance here. So I’m driving my D3 S8 (V10) yesterday when I’m idling at a stop light and the car just quietly stalls. I barely notice. Start it back up, it hesitates a bit when driving but can make it to the next stop light, then dies again. This happens a couple times. If I turn it on and let it idle, it will idle for about 30 seconds then just stall. I’m very close to home so I try starting again and driving, but EPC light goes on and limp mode. I clear the codes, wait 15 min, start it up again, and same thing happens. Then I clear the codes, wait 15 min, start it up, and drive 10 minutes home without any issues. When it starts, maaaybe it’s cranking a slight bit longer than normal…otherwise no preceding symptoms. Battery is full. Gas tank is full. Otherwise the car is (engine-wise) stock and pretty new to me and I have not done coil packs/plugs/fuel filter recently.

Here are the codes I’m throwing:

008756 - Oxygen (Lambda) Sensor B2 S1
P2234 - 004 - Signal Shorted to Heater Circuit - Intermittent
012555 - Low Pressure Fuel regulation
P310B - 008 - Fuel Pressure Outside Specification - Intermittent
000139 - Low Pressure Fuel System
P008B - 001 - Pressure too High - Intermittent
000135 - Fuel Rail/System Pressure
P0087 - 002 - Too Low - Intermittent
006435 – Please Check DTC Memory of ECU Number
P1923 – 008

So I’m thinking maybe dirty/clogged fuel filter? Maybe mechanical failure of HPFP? G410 fuel pressure sensor? It’s currently my DD because the 5cyl turbo is under the knife, so I’d like some ideas to try here. I do have VAGCOM so can log fuel pressures or whatever if someone can give me some guidance. Thanks in advance!!

mishar

It looks like your right fuel pump is dying. When you start the engine both pumps work for 30 seconds, than left stops. It kicks in only under a high engine load.

trillypop

Thanks for the quick reply! Right as in passenger side? You can tell from the codes?

The only thing not consistent is that the engine stalls under no load at all...happened when just idling. Still think it could be the HPFP?

mishar

Yes if your steering wheel is on the left side. Codes indicate low fuel pressure. If the fuel pump is not working properly fuel pressure will be low or none.

That's actually what happens if the right pump is not working properly. The left one works only 30 seconds after start and under near full load. Right pump works all the time.

haggisuk

I'm with Mishar on this one, your low pressure pumps are playing up, they feed the high pressure pumps so if they are acting up the high pressure pumps can't deliver the fuel and the engine will die.

I had similar stalling and starting issues with my S8 and it was due to the signal not starting the low pressure pumps, I know the fault codes are unrelated to yours but the symptoms of low pressure pumps failure is the same with running a bit then stalling etc.

I'm not sure if there is measuring blocks for the low pressure or not, you will find that you can't do adv measuring with VCDS because of some bull**** that's stopping them releasing the label file for that engine.

But if you find the label files for the r8 v10 they are close enough to use once renamed to suit the bsm engine and you can then use adv measuring blocks and log etc

If you need help doing the above just ask I can also give you a link to the manual that details fault finding the fuel pumps

Del

trillypop

Thanks for the info and replies guys. I'm pretty sure you're correct in suspecting the right side lpfp. I never timed how long until it stalled, but it seems consistent. What's weird is that today the car starts and drives just fine. I'm going to order the filter and right pump, possibly the left, and plan to do that asap...and hope that it doesn't act up again in the meantime. Thoughts?

haggisuk

Have a read through the manual, it gives info on how to check the current draw on the fuel pumps along with other tests that can help you determine what needs doing

manual

trillypop

Thanks for that, it's nice to have. Car stalled casually in a parking deck today, otherwise ran fine. Ordering parts now.

volvopentaman

Here are measuring value blocks for BSM (V10 450hp) engine:

Audi Portal: ECU Diagnostic . Audi A8 4E (2002 -) . Engine Control Unit J623

For use with VAS, but can as well be used with VCDS.

Measuring value block 103-1 is for low pressure (in millibar)
And MWB 106-1 is for rail (high) pressure (bar)

haggisuk

The blocks do match so if you put these files into your labels folder you are good to go.