So, I have not long since owned my 2002 vrs and love it.

I got the car for next to nothing due to the turbo being noisy, which I changed last week and now no noises.

I was told the car had been mapped.

The issue I am having is that the car hesitates under half throttle, and seems to drop the boost on Full throttle, I don't have a boost gauge fitted but I can feel it and hear the pitch of the turbo fluctuate at full throttle then settle down.

I have checked for boost leaks and all seems well, checked the forge DV (007p) and that does not appear to be leaking.

I have checked all vac lines and breather pipes and are all ok, no splits or cracks at all.

Also tried another brand new Bosch MAF that made no difference at all.

I plugged vagcom in which showed no fault codes at all (then the HDD in the laptop died so cannot use that to check boost vs requested).

Only thing I can think of now is the N75. The car was the same before I changed the turbo so it's nothing related to that. Also changed fuel filter, oil and filter and oil pickup pipe as a precaution when I got the car.

When the car is warm after 30mins of driving etc, 50% of the time it pulls smooth and and goes like a rocket like it should, then I can back off and go for the throttle again and it feels like I am down by 20bhp or so, before the car is nice and warmed up it seems down on power and hesitates.

Any ideas would be great, I cannot think of anything else left apart from the N75 being dodgy.

Thanks,

Ash.

Have you checked the Coolant Temp Sensor reading to the ECU on VCDS?

Throttle body clean is always worth doing if you haven't already done it.

Edited 24 February, 201313 yr by pauldazzle

Cleaned the TB, but not checked temp reading yet, need to repair my laptop before I can get back onto VCDS :(

Right, so today I changed the coolant temp sensor out of curiosity, which made no difference.

I also changed the N75, again no change, and also changed all 4 ignition coils, and no change (got a spare brand new set with the car).

Still cannot use VCDS due to waiting for laptop parts which is a pain.

Would a boost leak cause similar symptoms?

Have you tried disconnecting the MAF? See if it runs better with it disconnected

Sent from my Galaxy S3, not a Crapple!

Not ran the car with the MAF disconnected as I tried another brand new MAF that made no difference a few days ago.

I have noticed that the engine seems a bit noisy on idle, I can hear what sounds like an exhaust blowing sound (but quieter) coming from the middle of the inlet manifold, which is annoying as I had it all off to check yesterday :(

So I now presume I have a split hose, which one I don't know. Seems a nightmare to get any of the pipes off from under there.

Its not too bad under there once you remove the plate in front of the dip stick. Be careful with the dipstick tube though they can get brittle. Might be worth buying a new one anyway. There only about 4 quid.

There's a pipe under the inlet manifold commonly known as the S pipe. It's notorious for splitting & difficult to see if it has a split without removing it.

Edited 25 February, 201313 yr by pauldazzle

Spot on. Thanks for the advice guys.

I will remove the plate and have another good look over the weekend.

as the guys above my s pipe and pcv were goosed then the y breather died not long after lmao poooooo me thinks

Edited 26 February, 201313 yr by dubDEAN

Right,

Quick update, VCDS now back up and running so I had a look at coolant temp reading which was @ 84deg when i checked.

I have a set of silicone hoses coming to replace the S hose, and the one that runs from the PCV upto the Y pipe. Also picked up a new PCV from TPS while I was at it, might as well replace that while I have it all apart on saturday.

Also noticed that the requested boost over a 3rd gear pull was around 1.2-1.28 BAR of boost, so I presume this confirms it has been mapped?

Quick update, all sorted

Ordered a set of black silicone replacement pipes from a tuning parts store to replace the poor OE items and job sorted.

The problem pipe was the one that holds the PCV. Once removed and inspected I could still not see any cracks at all, and confirmed it to be at fault with the good old trusty mityvac.

Also fitted a 3" down pipe at the same time, and the car is a totally different machine now.

So thanks for the help guys