I own an MY03 STI that i bought in may. It fitted a full Vortex exhaust system to it from downpipe back and removed the intake silencer thing in summer and all was fine. Now in the colder weather i am having boost problems which seem to get worse the colder it is.

If i floor it in 4th, 5th, 6th at around 3500rpm you can start to here the turbo wavering as though its spooling up and down very slightly. If the weather is really cold the car will start to boost at 3500rpm and pull hard then die off a bit just before 4000rpm and then it will be fine upto redline.

Could this be turbo surge being caused by a slight boost spike due to the cold weather?

I know 03 STIs are prone to spiking when fully decatted but i still have the downpipe one which i thought would be fine.

Any help or suggestions would be greatly appreciated

 

sounds like overboost cos of cold air,

still under warrenty on 03 plate so take it back. think they may just reset ecu, thats what happened to my classic when it overboosted in cold weather, was like it couldn't make up its mind what it wanted to do accelerate or slow down when you floored it.

get it remapped should also solve your problems

 

I know what they will say at the dealership "It's your exhaust sir" and to be fair they are well within their rights.
Think i may just get a remap.
Anyone had work done at power engineering? Whats the overall view on these guys?