gonna get my car tuned next week on a wideband by phiz but i have an exhaust problem and cant seem to find the leak or the problem but it gets quite loud after 3000rpm and lacks in performance. if he tunes my car and i fix the exhaust after, will the A/F ratio be off and need to be done again?

 

well it depends... if the o2 sensor is lets say right after the header and there is a leak between the header and the pipe then it would be off. So if the o2 sensor is after the exhaust leak it would be off since those things read like super super sensitive but if the o2 sensor is before the leak then its all good.

 

i see, well it seems to make sense but i was thinking it would possibly affect it by back pressure or lack there of. im also baffles at the fact that i put on my silencer today to listen for leaks but still nothing! WTF

 

backpressure shouldnt' be a problem really.

 

Yup, it will. It's called sample dilution.

If you have an exhaust leak when you go get emissions tested, they will automatically fail you because they will get a false emissions reading from the leak, no matter how small... The test equipment will absolutely freak out, giving wildly false readings.

Same with wideband O2 in the tailpipe... It will read extraordinarily high O2, and will be totally false in what the engine is really doing...

Get the leak fixed. Hell, get a new exhaust...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Revolveu2 &raquo;</TD></TR><TR><TD CLASS="quote">Yup, it will. It's called sample dilution.

If you have an exhaust leak when you go get emissions tested, they will automatically fail you because they will get a false emissions reading from the leak, no matter how small... The test equipment will absolutely freak out, giving wildly false readings.

Same with wideband O2 in the tailpipe... It will read extraordinarily high O2, and will be totally false in what the engine is really doing...

Get the leak fixed. Hell, get a new exhaust...</TD></TR></TABLE>

thanks man! thats exactly what i was thinking would be wrong. i cant find a leak tho! i am gonna look more closely friday incase i might have missed someting...