No performance

[angus]

Looking for a bit of guidance here!

The OH has my old company car, a 2001 Passat TDi Sport which now has 136K on it and up to last week went like a train.

SWMBO informs me that it `doesn`t go anymore`, and when I try it out she`s correct. No go in any gear at any speed, and living on the side of the Pennines, down to first gear on hills.
Take it to my independant, who finds a vacuum hose air leak and fixes it. It would then pull, but only if you could get the revs above 2500. Within 24 hours it was back to being as bad as before.

Back to my indy, who then finds the AMM is out of spec and replaces it (Bosch part),and lets me take it out to see what I think. Its a lot better says I, but still not performing anything like it should at low revs. He puts it back on the computer which shows no fault codes, and everything well within operating ranges, but i know the car and its still flat at low revs.

24 hours later, its back to being rubbish again. daughter was driving it uphill and it dropped from 70mph to 40mph (when healthy it will pull three figures up this hill in top - allegedly:biglaugh:), and its totally flat across the rev range again.

I have some silicone vac pipe on order for this weekend (I`ll change them all as a matter of course), but anyone else got any ideas?

[dan~]

Isn't this an indication to MAF failure?

[martin1810]

As always the cheapest start is to change ALL the vacuum pipes.

[angus]

O.K, changed all vacuum pipes, same as usual, goes sort of for about half a mile then just falls utterly flat like turbo has been taken off.

Turbo vanes are supposedly clean and the actuating arm moves freely, the AMM is brand new and I`m getting stuck and frustrated.

Anyone?

[dan~]

Sounds like MAF.


Take it out and run the car that way, I believe you may have to disconnect the battery for 20mins or so first, so all the error logs clear.

If it runs better, without it, then you know it's the MAF and either clean it or buy a new one

[martin1810]

It could still be a vacuum leak. Ask your garage to vacuum test the pipes. I can tell you how to run a crude test yourself if you want to try.

[angus]

Dan - I may be at cross purposes, but what you refer to as a MAF I understand to be an Air Mass Meter (VW ad Bosch parlance)? If so, it had a new Bosch one three days ago (although I suppose it could be a duff one).

Martin - a crude test would be a good start, as my garage now want me to leave the car with them for `a few days` to see if they can trace the fault, which as I say isn`t throwing up fault codes. The phrase `a few days` sounds expensive!

[Frank.A]

Angus,

How about the MAP sensor which looks after intake charge pressure/temperature?

Best,
Frank

[martin1810]

Look at chrashers post on passat 2002 tdi sport thread. You can suck or try using a party balloon pump or bicycle pump. DON'T PUMP. USE IT TO SUCK. If you have no leaks, even after 30 secs or so you should still feel vacuum trying to pull the piston of the pump back. It's worth waiting a few seconds in case you have a small leak.