intermittent turbo?

[adycass]

guys. had my golf gt tdi 150 4months now. twice the turbo has appeared to stop working?
once last month, and again this morning. i stopped, turned off ignition to have a look. nothing visible on both occasions. started car and problem was gone?


any ideas im hoping to get it vag commed tomorrow at vw fest. will this show anything??

[Rhyso]

sounds like you've got a boost leak somewhere mate

get it up on some ramps or jacks and have a good poke around the pipes

also check your vacuum pipes for splits etc

[ToddyGTi]

Intermittent Fault With the Air Mass Sensor. When this goes the ECU will not allow any severe boosting on the turbo to stop you from blowing it to pieces.

If the AMS is at fault, just disconnect it and drive the car. It'll smoke a fair bit but should go like Sh*t off a stick. If this is the case, replace it and only buy a genuine one. Aftermarker ones fail again after about 3 months.

[vRStu]

Sounds to me as though it's going into limp mode, turning off the engine and restarting is clearing it.

A couple of things that spring to mind for me is -

MAP Sensor - Not the MAF sensor but the sensor which tells the ECU how much pressure is in the induction side of the boost pipework.

VNT Turbo Vanes - Very common on older/higher mileage cars, the vanes move to supply maximum boost and then when you lift off they are jammed in the maximum position causing an overboost.  The turbo can be cleaned but it isn't always effective.

N75 - A faulty N75 would mean that the turbo vanes are not moved properly to match the engine load.