Question for people using test pipes

[Tool Man]

I'm putting a test pipe on my Sons car, and noticed the O2 sensor is behind the Cat. For those of you who have done it, does it make the car throw a CEL and make the car run rough?

 

[IHeartTurbo]

Yes, most likely it will throw a CEL, because the ecu doesn't think the cat is doing it's job.

 

[leet]

I don't have a CEL, but that may be due to the fact that the OBD2 system on my car came screwed up from the factory. Go Mitsu

 

[heavyD]

There is a 70% chance that you won't throw a CEL. Mine didn't but some cars do. It doesn't affect engine performance as the second O2 sensor is only there to ensure that the converter isn't clogged up.

 

[Tool Man]

Thanks guys, he said he can deal with the CEL as long as it runs ok. Thanks again for the quick replies.

 

[DSMeclipse4G63]

there is a chance it will throw a cel, but it is only a catalyst inneficiency code and doesnt affect performance or gas mileage. There is a chance the ecm may go into"default" mode, where it will lean or richen the car out to try and accomodate for the cat missing...but that is HIGHLY unlikely. I had my 95 gst without a cat for 2 years and the cel came on sometimes and others Id reset it and iot wouldnt come on for a month or so. I still got great performance, and well over 400miles to the tank.
Andrew

 

[karbon]

Regardless of whether it throws a code or not, doing the elimination procedures aren't hard and guarantee that it won't throw a code. http://www.vfaq.com/mods/O2bypass.html

 

[heavyD]

Regardless of whether it throws a code or not, doing the elimination procedures aren't hard and guarantee that it won't throw a code. http://www.vfaq.com/mods/O2bypass.html

It works but the resistors burn out too frequently and I could always smell it. Put the O2 sensor back on and no CEL's anyway.

 

[miteclgst]

I had a CEL that would come back every once in a great while, real damp cold weather would be the most likely. When I first did it, a long time ago, I would get the light more frequently but then after resetting the computer a few times it went away for good.

 

[Tool Man]

He decided on a high flow cat and e-bay 2 1/2 stainless catback exhaust, so the O2 is intact. It sounds good and was a fairly easy install.