madmarx

iTrader: (1)

I recently fitted a Sti sports cat downpipe to my WRX turbo and at the same time i had to replace the post cat o2 sensor with a second hand one as my old one was seized in the boss. Now the car pops back on deceleration and seems a bit rougher in the lower rev range, is this because of the bellmouth downpipe ? or is the lamda not not doing its job correctly. No EML lights have come on, car has run for the last 3 weeks like this. I quite like the occasional popping by the way.

Exhaust spec is de cat up pipe, Sti downpipe, 2nd de cat and Prodrive backbox.

MattyB1983

iTrader: (51)

Has it been mapped ?

s400byk

You need a remap for those thats why you are getting the rough low revs..

daz1968

iTrader: (13)

And the popping will be due to over fuelling, mine did it when I fitted the same parts on my wrx. Best to get it mapped will be much better then. You can still have the pops and bangs though if you want

madmarx

iTrader: (1)

At last a good answer. Yeah i know popping back is unburnt fuel igniting, i was just seeing if it had anything to do with the exhaust, i didnt think changing the downpipe only would alter the fuelling that much.

MattyB1983

iTrader: (51)

If you had answered post two then you would of got an answer.

Your car needs mapping.