poss o2 sensor?????help!!
 

hi all,
my mate has a uk turbo and the revs have started to dip at junctions, but only really when the engine is warm,also he reckons sometimes when he pulls up and it does it that it smells rich!
another thing is sometimes when its cold and he drives up a hill the engine light comes on and the code says o2 sensor,but could that be down to the decat downpipe as it has always done it,but now it stays on for longer!
he has replaced the maf sensor,although with a 2nd hand one but its the same still!

could it be o2 sensor,as its the obvious thing???

hope you can make sense of that,lol!

My old uk98 used to be fine when it was cold but once warmed up did the same dipping, it would idle between 100 and about 400rpm. I replaced the MAF and reset ecu and that sorted it. Common thing on Impreza's.

i thought it could be the maf sensor so he changed it and has made no differance!

Unplug the o2 sensor, Go for a run, does it run better ?? If so, then it will most likely be the O2 sensor. With it unplugged the Ecu will be using the base map for it's air/fuel ratio's with no adjustment from the O2 sensor Etc.

It won't come to any harm for a test..

Dean