Blacktt3z

I have a 2001 S8 and recently the car feels really slow and almost bogs down on acceleration. It has new plugs, fuel pump, fuel filter. Any idea what would cause this?

Thanks

the_duke

VCDS codes? Could be any number of things and codes are the best place to start. You could also check your intake flaps and make sure they are functioning properly. Maybe clean your MAF.

Blacktt3z

Is there a good way to tell if the maf is faulty?

silverd2

Yes .... "VCDS codes?"

MikkiJayne

It can be faulty and not throw a code - i've just had this with mine tracking down a lumpy idle.

Switch between measuring block 99 and basic settings 99 in VCDS to switch the O2 sensors on and off. If the MAF is bad it will run like poop with them off and then get better over a few seconds with them back on. Basic settings 99 turns them off, exiting (or going back to measuring blocks) turns them back on again.

Also look at basic settings 32 and 33 for the O2 adaption values. Any more than 5.7% deviation is bad. Mine was pegged at 25%! If I unplugged the MAF at this point the values would come right back in to line and it ran fine.

I've got a new Bosch one to be fitted this afternoon

silverd2

Gee, it looks like you used VCDS to find the problem.

Surprised that no one suggested that (?)

MikkiJayne

Haha fair enough Not quite as simple as fault codes though

silverd2

Agreed.

My point is that if you're going to work on your own car, especially "modern" vehicles, you need the proper tools (manual, VCDS, etc..) or let someone else do it.

Online forums alone can rarely definitively diagnose anything other than an obvious tangible (see it, feel it) problem.

Cheers

jfrahm

Best bogging video ever: