VW GT TDi intermittent turbo fault..help please

[batfink79]

Hi all,
A quick one, the other half has a V reg GT TDI, lovely clean car, however, the turbo on it is cutting in and out. Ie, after cold start, it will run for about forty/fifty miles etc, pulling like a train, then the turbo just stops working and it becomes v v sluggish (obviously lol). when you turn the ignition key one click back, then back to the start position the car resumes running, the turbo is spooling up etc, all fine, however, 2 to five to ten minutes later it cuts out again.....
have spoken to the local VW garage who say they have the same problem with their sharan, but they have no idea whats causing it, but that they have pulled the engine apart trying to locate and fix it.
any ideas?

many thanks for your help,

finkers

[phumy]

The turbo does not run from the ignition system, it runs off of the exhaust gases, so i think you are looking at a red herring. You might have a dodgy connection from/to your MAF sensor, or it could be a multitude of other problems. Take it to someone who knows (Dealer or Indie).

Good luck

[Mikey-S]

Classic signs of the turbo overboosting then going into limp mode. Read your DTCs with vag-com or similar, and I'll bet you find one about boost control. Poss a stuck wastegate.

[philip walker]

Read the codes first if as suggested its boost issue it could be as follows.

Could be a air leak in the small pipes that connect to the boost and egr valves.
Or it could be the turbo variable vanes are clogged up with soot/crud. We usually remove the turbo stripp off the exhaust hot side and ultra sound clean the exhaust turbine.

Works a treat.

[S2AVANT]

N75 valve, either getting the wrong signals ( due to worn out pipes) or it's fooked.
As stated above the turbo isn't electric so flicking the switch shouldn't cure a turbo fault.

[philip walker]

If the fault is a boost issue it will cause the ecu to go into limp. This is cleared when you turn the ignition off then back on.

We do loads of cars with the identical symptoms in my workshop.It generally one of the two faults suggested.

Edited by philip walker on Saturday 19th January 09:15

Edited by philip walker on Saturday 19th January 09:16