A buddy of mine told me that exhaust leaks have been known to rob power, he wasnt specific about the size of the leak. He did tell me however that on a dyno an exhaust leak cost someone he knew about 20 rwhp, im not sure whether to believe him or not. I was wondering if anyone ever heard of anything like this? Thanks.
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I'm no expert but from what I read here. An exhaust leak can give you incorrect O2 readings. I don't remember if it makes it run lean or rich. I would also think the tricking you hear would set off the knock sensor. I sure others will chime in.96 Camaro Z28/A4,Vortech elbow,Moroso CAI,Flowmaster.Addco PHR,LCA,160* Stat,pcmforless,1LE Driveshaft,1LE A/C delete pulley,1LE Front sway bar,Strut brace,sub frames, LT4 knock module,255 lph pump,Cutout, -
Yes, the exhaust moving past the leak actually pulls (educts) air into the exhaust gasses through the leak, and the O2 sensor "sees" the extra air, assumes its running lean, and richens the mixture. Adding fuel it really doesn't need over-richens the mixture, losing power.
A misfire will do exactly the same thing, dumping air into the exhaust.
Its only an issue with electronic fuel injection using closed loop control.Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motorComment
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Correct. Firstly, an exhaust leak near the knock sensor can present a "false knock" situation. Depending on the amount of knock retard, it can rob several horsepower.
In addition, a leak before the O2 sensor will make the O2 read a "false lean" condition since it sees more oxygen. Once the PCM sees this information, it tries to compensate by richening up the mixture. That hurts for peak performance. With a combination of the two, I'd say 20 RWHP may be right for a bad leak that's causing KR and incorrect A/F mixture.
EDIT: Sorry for the repeat...Fred beat me to it
94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...Comment
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