waskliewbt

Hello all,

In the last couple of days my 00 2.8 30v Avant has been randomly dying when slowing down and sometimes at idle. Also the trans (or something on the drive-train) is putting out a rather violent thud or clunk when approaching 40mph and after that the car can only go around 40, no faster.

Happens randomly though. Its our only car so weve been using it only to get to and from work. Some trips it happens frequently, others the car drives completely normal no problems at all.

Its getting more concerning though because just now my girlfriend was at the store and the car would start and the immediately die. We had to pull the battery yesterday to put it on the tester at work and then it drove fine, so she walked over to Big-O today borrowed a wrench, unhooked the negative cable for a minute, put it back and now its starting and driving no problem.

I'm stumped. Only codes pulled over the last two days are:

Address 01: Engine
Controller: 3B0 907 551 G
Component: 2.8L V6/5V G 0003
Coding: 07251
Shop #: WSC 06325
2 Faults Found:
16815 - Warm Up Catalyst: Bank 2: Efficiency Below Threshold
P0431 - 35-10 - - - Intermittent
16486 - Shareware Version. To Decode all DTCs
P0102 - 35-10 - Please Register/Activate - Intermittent
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 02: Auto Trans
Controller: 8D0 927 156 AT
Component: AG5 01V 2.8l5V USA 3132
Coding: 00002
Shop #: WSC 00000
1 Fault Found:
18265 - Load Signal: Error Message from ECU
P1857 - 35-10 - - - Intermittent

Anyways, any ideas?

4Driver4

Time to get the full version of VAG-COM and do some more detailed diagnostics of the trans electronics.

waskliewbt

Ok. If I was able to get my hands on the full version what in particular should I be looking for?

4Driver4

I would use the measuring blocks and output tests along with the Bentley manual to try to figure it out.

waskliewbt

but at the moment, I dont.

This car is now the only way of getting two and from work where we make minimum wage in a tiny middle of nowhere town we got stuck in. The only thing I care about right now is just being able to get to work and get food for my family.

I'm leaning on MAF, because on measuring blocks while its acting iffy its reading 0g/s and running like complete *** (if its able to run at all). I have a feeling this is what is also causing the thud because the engine thinks its running at 30-36% load at idle and is sending mixed signals to the ECU then TCU.

My problem with this is, why the hell does it start and run just fine for a while if I disconnect the battery for a minute?

I went ahead and ordered a new MAF from work but I still cant figure out if that is even gonna make a difference. Why would the car act perfectly fine after disconnecting the battery? ECU? Wiring?

I normally find everything through search but I'm really drawing a blank on this.

5v/cyl

The 'Load Signal Error' could be a symptom of a bad MAF. Unhooking the battery is wiping the the codes including a TCU error code. A VAG-COM would narrow it down, but until then you can really only guess.

Bruddah_John

I have a '99 A4 1.8T Quattro and had similar problems come up twice in the last couple of years. My mechanic had tried a new MAF, tested the ECU, and checked the coils but there was no improvement. He traced the problem to the wiring harness to the ECU which had become brittle over the last decade from exposure to the heat of the engine compartment. The damage caused a circuit gap from the ECU to the MAF causing the engine to cut out and stall. Audi doesn't carry the harnesses and it's very difficult to find, not to mention really expensive new -- you may be able to find one in good condition from a salvage yard. He did a good job of repairing the damaged wiring and I have been without symptoms ever since.

Good luck!