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Exhaust leaks and fuel mileage

This is a discussion on Exhaust leaks and fuel mileage within the General Help forums, part of the LSx Technical Help Section category; Ever since I got an exhaust leak I have noticed my fuel mileage drop 15-20%. The leak is at the ...

  1. #1
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    Exhaust leaks and fuel mileage

    Ever since I got an exhaust leak I have noticed my fuel mileage drop 15-20%. The leak is at the header at the pipe to convertor.

    The O2 sensors are new.

    Two of us say that the leak can drop overall fuel mileage by causing the right bank to run richer, one says no.

    Am waiting on my new exhaust system. Leak has been around since a month after I replaced the O2's as I had to crank on one size to freeze up the seized sensor.

    Mileage was great before the leak became noticable.

    Thoughts?

  2. #2
    O U 8 1 2 Spaz's Avatar
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    that leak will cause your sensor to detect a lean condition and throw more fuel in tot he engine... look at your exhaust tips... they are probably black as coal... have you thought about getting a clamp and welding it over the leak???

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    Life in the Fast lane sunsetorangess's Avatar
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    Band clamp maybe?
    J
    2001 SS, Its not the car its the Driver that matters....

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    I'll get to it when the weather breaks..Been raining and snowing off and on.

    Looks like 30 minute job at most.

    Thanks!

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    O U 8 1 2 Spaz's Avatar
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    Quote Originally Posted by sunsetorangess View Post
    Band clamp maybe?
    J
    one time... at band clamp...

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    We'll be back... GatorSS's Avatar
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    Ditto on the leak causing a false lean condition detection resulting in extra fuel added to that bank. Ergo, your fuel mileage drop.

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    Life in the Fast lane sunsetorangess's Avatar
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    Quote Originally Posted by Spaz View Post
    one time... at band clamp...
    Lol Yatzeee

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    Quote Originally Posted by Spaz View Post
    that leak will cause your sensor to detect a lean condition and throw more fuel in tot he engine... look at your exhaust tips... they are probably black as coal... have you thought about getting a clamp and welding it over the leak???
    exhaust leaks pre-o2 sensors do just this.

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    After fixing the leak, and being that the PCM has detected the lean condition and added more fuel, would it be wise to unhook the battery to reset, or allow the problem to correct itself?

    Thanks..

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    it will correct itself. it's pretty sensitive that's why we have 4 o2 sensors. it instantaneously reads what it sees and adjusts fuel accordingly.
    2000 red ss: >2" drop, koni adjustables 'n 275 s-compounds all way around, giant brakes, dynatech LT's, borla catback (no plate), t56, tubular everything, HARD TOP, caged, "stock" heads 'n a mean cam. -2* front camber.

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