cparke

Hello everyone once again,

This Audi A4 V6 5V I have is really getting very angry at me for trying to fix it. I changed the engine coolant temperator sensor (what a PITA, especially pulling and pushing the actual sensor into/out of the pipe!) per advice here in the hope this might resolve my System Too Rich fuel trim problem. Doing that involved removing the Intake duct from the throttle body, and that is not my idea of fun!

No dice, once again (this happened previously when the new MAF was installed last week), every time I do something to help the car, the condition that I'm trying to fix actually worsens. At this point, my car's computer immediately (really) upon being reset throws this fault code:

17549 - Load Calculation Cross Check: Implausible Value
P1141 - 35-00 - -

Shortly afterwards with some driving we get the other two faults:

17535 - Fuel Trim; Bank 1 (Mult): System too Rich
P1127 - 35-00 - -
17537 - Fuel Trim; Bank 2 (Mult): System too Rich
P1129 - 35-00 - -

Fuel trims are now basically this bad:

Group 032: O2S control learning values (before Cat. Conv.) [B=Bank S=Sensor]
-4.7 % @idle B1S1 +/-10%
-25.0 % @part B1S1 +/-10%
-4.7 % @idle B2S1 +/-10%
-24.2 % @part B2S1 +/-10%

The ECU appears to be so unconfident with its learned trim that it decides to clear its learned values each time the car is turned off. Now too, it seems the ECU is deciding to just not to even try finding a trim and leaves the values at 0.0%!

The only positive sign I've seen from the latest numbers is that bank 1 and bank 2 are now nearly equivilant. The problem could still very well be a vacuum leak, since every time I do a repair, I am obviously also moving wires and vacuum lines around. Whatever this problem is (and I'm very tired of it myself), my time to find it just about up now---I don't think this car will be running much longer if it stays in this condition.

I am now praying now that a mechanic I brought the car to can find a leak or bad FPR that makes this all go away, or if not, when I put in a new fuel rail with FPR and 6 new injectors as the last resort, the problem will go away. Pray for me all of you too, please. I just want a normal running engine in my car for Pete's sake!

DaveInSaltLake

start learning all over again.

cparke

I've never seen it do that before. The engine learns trim of -24.2% and -25%, then turn off the engine. When you turn it back to ON (don't even have to start the car), it is back to 0%. Once the MIL is on, I think it stops learning too and maybe will just stay stuck at 0%. How hard is it to swap the ECU with another car to see if the chip for managing fuel trim is going haywire?

DaveInSaltLake

I'd probably leave the battery cable off overnight to reset the ECU