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Thread: Signs in VCM of a vacuum / exhaust leak

  1. #1
    Tuner in Training
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    Signs in VCM of a vacuum / exhaust leak

    What would one look for in VCM logs that would show a possible / exhaust leak issue?
    On a quest to not blow up my car.....

  2. #2
    Tuner in Training
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    look at both banks o2 sensors if you have a leak the fuel trims will be erratic

  3. #3
    Tuner in Training
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    Quote Originally Posted by Matt1231 View Post
    look at both banks o2 sensors if you have a leak the fuel trims will be erratic
    Here is a log I just ran today, Fuel trims look ok, but o2 seems to be erratic. Does this seem to be a vacuum/exhaust leak?

    10-15-19 log.hpl
    On a quest to not blow up my car.....

  4. #4
    Advanced Tuner
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    You are around 11inhg vacuum at idle (should be around) which could indicate a small leak. I know that with challengers the intake manifold bolts can loosen...actually quite common as quite a few guys on the CT forum confirmed theirs were loose. Mine were loose at only 18,000 miles on the clock (no loctite on threads) and required ~2.5 turns until correct torque was reached. There were fuel stains right at the head/intake connection which tipped me off.