Rear 02

[tomtom123]

Will the flexpipe on my headers leaking pretty bad, would that affect my fuel trims and what not? I have a rough idle and the car one day wants to idle lean, and the next wants to idle rich. Coule this leak affect that?

Does the rear/downstream 02 affect fueling?

[stealthee]

The downstream (post cat) o2 doesn't affect fuel trims. It is just checking cat efficiency.

[tomtom123]

Okay. So the leaking flexpipe affects nothing?

[Impala131]

Might throw a code for the catalytic converter, that's about it, assuming it's a 97-03 GP.

[tomtom123]

Yeah. 99. No code for cat. Also, no cat on it =P

[Fivefingerdeathpunch]

Anything after the front o2 sensor doesnt matter on 97-00 cars. 01+ would run the cat test if it kept seeing a p0420 for the cat or because the leak was causing more oxygen to enter before the cat.

[tomtom123]

I had a P0420 for a while but figured it was possibly due to my fuel csnister not sealing properly. After I replaced my fuel pump I got the canister in place and the o-ring and everything on it and it still overflows when I fill up my tank.
However, 2 days ago the code shut off

[Iceman6669]

I thought I had shut that code off... But I just looked at the bin file and I musta missed it.

[tomtom123]

I don't think it would have mattered, last I heard the 99's didn't set a code when the cat was removed?

[Iceman6669]

**** IDK. I meant to shut it off though. LOL

[tomtom123]

Well I think it's off now =P
Either that or the SES light burned out o.O
Lol

[Iceman6669]

LOL

[tomtom123]

But the rough idle and unsteadiness is still kinda there. And I still don't know why I see so much knock on this thing >.<

[Iceman6669]

I gotta think that most of your knock issue is the Knock sensor being too tight.

[tomtom123]

Yeah, I don't doubt that lol. I wish I woulda known about knock sensors when I put those stupid things in =P