Hey guys,

First I'm gonna bore you with some back story. My problems started a few months back when i had my vRS remapped. It was decatted, and had a "mufflerectomy" which was explained to the remapper (Unit18 if anyone wondered). It was done on an 83000 mile old turbo, so very quickly the turbo blew, and this has recently been replaced with a Garrett unit (as opposed to the KKK which blew). Since the new turbo the car has seemingly run fine, apart from the annoying loud whistle, which Ive been told in normal being as the car has a decat.

A few thousand miles later and my latest problem came about, just a few days ago. On my way back from a short drive, with both parents in my car, I had a sudden loss of power, and quite severe increase in exhaust noise, and what I presume was 'limp mode'. A pull over and restart of the engine cleared this up, however since then my car has felt down on power. Up to half throttle it seems to pull fine, but after half throttle it doesn't give any more power, unlike before. Also every few times I accelerate hard in 5th or 6th, it seems to go into 'limp mode' again.

My initial thought was a minor boost leak, however I had some Samco boost hoses lying around, which I installed today, but again in 6th gear under hard acceleration I had a loss of power and had to restart the car.

Can anyone think of a possible solution? I had the car scanned a week or so ago as I had to replace an ABS sensor, and only the ABS sensor fault came up.

I would really appreciate any suggestions you guys have.

Ross

PS. Sorry for the long post buut hopefully writing this much information means I shouldnt have to answer too many questions

Edited 18 June, 201115 yr by InFus1on

I would scan the car again to see if any new codes are logged. It sounds like it's over boosting and this can be any of a number of things.

If you get codes we can go from there. If no codes, it will be harder to pin down, but the things that will need checked are.

1: N75 vacuum control for turbo VNT

2: VNT actuator moves freely when vacuum applied.

3: Boost pressure sensor on inter-cooler

It looks like you are running a straight through exhaust? really bad idea on a VNT turbo, if a new turbo is whistling excessively, either it's not getting enough oil (what are your oil temps and EGT measurements?)or it's over spooling.

I would do a VAGCOM log with assistance from a passenger (back seat away from airbags)under WOT and log boost pressure and MAF values.

Mogg,

Im planning on installing a Cat again ASAP, Im just struggling to source one, so hopefully that will decrease the whistling. I still have the two middle silencers in the system btw.

I think (hope) the turbo might be ok because its only 2000 miles old, but of course Im not gonna rule it out.

The problem with my last turbo was the vanes were sticking, could there be a fault somewhere else causing these to stick also? The turbo still feels strong, and until last week was perfect.

Full car of weight, turbo working harder, no cat and no back box. Sounds like over spool.

If it did overspool, how would I go about getting it back to normal again?

If it did overspool, how would I go about getting it back to normal again?

Turbo VNT actuator can be adjusted mechanically by most good tuners. Should ideally have been done when new turbo fitted, as the actuator is adjusted at manufacture for standard map.