O/T Audi A4 - Can't rev past 3500rpm
Turbo Mini Forums

Hopefully someone on here maybe able to help. Tom??

I've got a 56 plate Audi A4 2.0 TDi, i've noticed latley that sometimes it's underpowered, don't think it's the turbo because you can feel it kick in.

It's more that even with your foot flat down it was struggling to rev freely and wouldn't get past 4000rpm under load. It's a bit intermittent as a bit later on in the journey it will rev and drive as usual.

Yesterday it got a bit worse and started to misfire under harder acceleration, if you feather the throttle it drives ok, however it will not rev past 3500prm even when it's not underload, just sat on the drive, foot flat down it rev's upto 3500rpm.

My thoughts are either Fuel Filter, Fuel Pump or MAF. I've done a bit of searching about on the net and the MAF keeps coming up as a possible cause.

The car has 75K on the clock and is fully serviced by Audi, however I've stripped the airbox down to remove the MAF and if the airfilter in there was changed at the last service I'll eat it. Same goes for the Fuel filter, that's never been changed before.

Also, I'll admit i've run the tank very low a couple of times recently, i know, i'm an idiot.

Any help/thoughts would be appreciated.

change the fuel and air filter first, (fuel filter being the key) of that doestn sort it, its the MAF or a blockage in the exhaust . but my monies on the maf! as exhaust blockages (like particulate filter) usually get worse as the journey goes on.. running the tank low shouldnt cause any harm IMHO. i know people scaremonger about it but i run my diesel right down as do othe rpeople i know and none of us have had issues with lift pump failures or that.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

MAF MAF MAF MAF MAF MAF MAF.

whip it out, give it a clean. if all is fine after that you know what you need.....

easy to see if that is the problem without spending any money so start there.

MAF gets my vote. I've got a Golf and it did exactly the same thing when mine started playing up. Buy a genuine one (about 60 quid) rather than a pattern part as they tend to last longer, so I've been told.

Cheers for the replies guys, it seems to point to the Maf, so heres hoping. I'll pick one up on Monday with a bit of luck.

Or just take it to a dealer, it should still be under warenty....

As others say. I have a comms lead so could try to plug it in and see what you get if you like?

I've got a black box for reading ecu's if you want to pop over and plug it in

problem is MAF failures often dont show up. only way to detect them is to have a known good reference to compare teh suspect maf with, either on file or physically :) if you have (for example) a choked exhaust or choked fuel supply, the maff will flatline when the engine goes flat, just as it would do if it had a duff maf. still, 99.9% chance its the maf :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

first mistake is trusting a main dealer! find a good specialist - I did and it hase saved me fortunes

sounds like the MAF though

Not under warranty any more due to the mileage.

Got a MAF, air filter and fuel filter on order. I'll give them a go first and if no joy I might take you guys up on the offer to plug it in.

but do make sure you find a good specialist, someone i now took their a3 tdi dsg to a german car specialist to have the dmf changed, the "specialist" stuck ordinary auto oil in the gearbox and fucked the whole box! its going to be nearly 6k to get it sorted.

I use a place at meadowhall for mine. Just for servicing and stuff I can't (be bothered to) do myself

same problem i had with mine

was the maf

easy way of telling if its the maf is unplug it and run it up the street

Edited by wolfie on 29th Mar, 2009.

just clean the maf and give it a run.you wont be wasting any money then.

or as wolfie said. No point buying stuff you dont need to.