Hi all,

I have a problem with a Passat that some of you helped with previously, however it still exists and the garage have no idea where to go next.

To recap on the problem. I have a 2002 Passat 1.9 TDi 130 bhp, AWX engine code.

Intermitely (4 times in the past 4000 miles) the car loses a large amount of power, mainly struggling in 3 or 4 th gear. With the gas fully down in second theres no acclration until around 4000 revs. Then its only a little boost.

Diagnostics so far:
Previously I have been able to resolve the issue by turning the engine off. Openning the fuel cap to allow air into the tnk and starting the engine. However it hasn't work this time.

The car has gone into the garage and they found a fault code:

17964 - Charge Pressure - Negative deviation in Turbocharger wastgate regulator valve.

The garage removed the hose leading into the regulator. They said it had a leak on the hose and replaced it. They also checked the voltage and impedance on the unit it connected into - they read 12.34 volts and 16 ohm so in range for the device. Next they deleted the code and tried the car out - still no acceleration.

The garage are now confused and not sure what to do next. Its been to two garages, one wanted to do a compression test as they felt it was misfiring. THe car does judder and jump when stationary indicating a missfire. However the second garage believe the misfire is due to this negative pressure.

On a side line when starting the car from cold a large amount of white smoke, smelling strongly of diesel (not oil) comes form the exhaust. Its enough to cloud the view in the rear mirror. It only happens on first startup from cold.

Any thoughts anyone? I've seen that some people on here have the same problem and are talking about a N75 - is that the unit I mentioned above??
thanks for all your help.
Richard