I took my test pipe off tonight just cause I was bored and wanted to hear how it would sound with open downpipe and when I started it up it the idle was'nt stable. It would go from like 850 for a second then drop to like 650 then back to 850 it didnt die or anything just sounded like it was cammed lol. I put the test pipe back on and it was fine again. Is this normal on these cars? I know on my subaru it would idle fine with open downpipe. I am tuned for a turbo back by the way

 

does anyone know the answer to this...?

 

The configuration has to be loud. So, it could be that the knock sensor was picking up the noise.

 

Could have possibly been that the o2 sensor was reading anything, so maybe the idle was a bit weird

 

Well It was showing no knock at all at idle so I dont think it was that. My o2 sensor wasnt connected to anything though that may have been the problem. Thanks for the response

 

If you were to continue to run around without a TBE then the ECU would "learn", it could also be the knock sensor or the second O2 sensor not in the exhaust stream.

 

yea the second 02 was just hanging there so I think that is what the problem was lol

 

sounds right to me