I've had my 2001 S-turbo for about 5 months now and nearly the entire time I have owned it it has had this surging issue under acceleration. I have done a fair bit of internet searching and replaced; the o2 sensor on the exhaust behind offside front wheel (UK car), the MAF metre, Fuel filter, Spark plugs (platinum), Air filter, and had it serviced. None of the above have mad any difference. Had diagnostics on the car at idle and while ran down the road while the problem occurs and no faults are coming up. There's also no signs of any boost leaks. 

Any information is very gratefully received as I'm out of ideas. 

Cheers,

Will.

Hi mate, just to clarify what do you mean by surging ? Does the car keep accelerating when you lift off or at idle ? Sorry for daft question

Does it sort of rev before it pulls. If so that will be the clutch on it's way mate. But if that was done not to long ago what fuel type are you using ? 

And might be worth giving the throttle body a clean through too 

Or maybe a boost spike or wastgate not opening properly ?

Thanks for the replies. If you are accelerating from low revs best example third of fourth gear, throttle pedal in a constant position it feels like you are either pulsing the throttle pedal, or its is coming on and off boost. Good rhythm to it, its quite odd. In my mind it feels more like a boost issue, but everything appears to be working as it should.

 

Always use super unleaded, and my next line of attack was to start cleaning and replacing what I can on the pipe work and maybe plump out the re-circ valve as I've read they can be problematic.

Thats a good start - check a piece at a time

I would start with the pipe work check it's all secure and in place and no split's. Best ways to have a squirt water bottle with a bit of washing up liquid and just spray around the pipes with the engine running. I'm sure I don't need to remind you to be careful of some parts in there too :D