slow A4 2.5 tdi

[wavey-davey]

hi im still having problems with my A4 2.5 TDI. tried another MAF, changed all vacuum pipes, checked turbo actuator rod is moving all the way it should, still exactly the same. its not limp mode and cycling the ignition does nothing. diagnostic said boost pressure is ok but MAF readings are low. after changing MAF these are still reading low?? could it be the ECU?

[deeb]

sounds like your in the same position as myself, Degsy has mentioned in another thread that he fixed his by replacing a fuse near the ECU, I'm getting my diesel pump checked as I've been told it could be the problem.
EDIT: you could also check the 'N75' to see if that has failed.

[olds_kool]

did you fit a genuine maf or cheap ebay joby?
have you tried dismantling vnt mechanism?
have you tried with cat disconnected?

[Alan02]

hi im still having problems with my A4 2.5 TDI. tried another MAF, changed all vacuum pipes, checked turbo actuator rod is moving all the way it should, still exactly the same. its not limp mode and cycling the ignition does nothing. diagnostic said boost pressure is ok but MAF readings are low. after changing MAF these are still reading low?? could it be the ECU?

Dont know if you`ve had previous posts,so forgive me if this is a repeat question,but when was the Fuel Filter last changed? Always a good place to start.Cheers.

[wavey-davey]

yes tried with a de-cat pipe fitted, with front pipe only, vnt mechanism is free and moving fully to its stops, and the MAF i tried on was off a perfect running car with no problems. it was a genuine bosch exchange not an ebay jobbie. according to the diagnostic ive had done the boost pressure is reaching what it should be on screen, but the MAF reading is not reaching its target value, and it was the same with the other MAF fitted. next step is to try to get a vag-com scan done and log the readings of the MAF,N75, turbo etc to try to see whats going on.
do you know if vag-com can check my pump timing? many thanks!

[deeb]

Finally got mine sorted, an idiot previous owner had limited the accelerator peddle, probably to get it through its emission tests. Not sure how many years and how many mechanics have missed it but I've taken it to 3 since I've had it.