TDI gone slow plz help

[fahafiz]

hello people,
my 90bhp TDI is a little slow, in 1st and 2nd gear it goes up to about 3000rpm or more.... but in 3rd when reaching 2500rpm the car feels as tho it is holding back... same in fourth gear... any suggestions?

 

[RobM]

MAF is quite a likely cause of this, very common problem. Do a search for MAF and see what you find (expect lots of results!!)

 

[sssstew]

yeah agreed first port of call. unplug the MAF sensor (the one after the airbox) and see if its any better.

 

[fahafiz]

right how do i unplug it? is there any risks/dangers if i dive a mile with it unplugged...

 

[RobM]

It unclips and slides out, just be careful and don't go yanking it out.

You're safe to drive for a while with it removed. What happens is the ECU uses default values and values from other sensors when there is no MAF reading. This may make your car slower, or faster, depending on the problem. But it should drive smoothly and evenly and that's the important thing.

 

[fahafiz]

right, ive unplugged the MAF and its worse... i cant feel the turbo pull when driving from 1900rpm onwards... any more suggestions?

 

[sssstew]

it think it would best to get VAG COM on it and see for any logged faults, and also take the chance to log the MAF requested vs actual and Boost requested vs actual.

 

[ChrisG]

I'd still bet on it being the MAF even if it gets worse by unplugging and even if it doesn't show up on VAG COM.

My TDi Bora had exactly the same symptoms, engine felt strangled above 2500-3k rpm. There were no VAG COM errors and it was worse when I unplugged the MMAF, yet it was at fault, I only found out when it eventually went completely and ran like a complete dog.

The really annoying thing with this particular failure was a few months earlier I swapped the MAFs over with my missus's TDi Leon and it didnt improve, so I assumed it couldnt be the MAF. It wasnt until the Bora MAF died completely and I got a new one that I found out that the one in the Leon was also faulty!