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Thread: Lean Cruise without detonation

  1. #1
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    Default Lean Cruise without detonation

    Im pretty sure that my knock sensors do not work becuase I can't remeber the last time ive seen knock but I can definately hear it.

    Anyway with my 02 switchpoints lowered I think its causing it to lean out when the TC is locked at high loads in low rpms. Does anybody else notice this?
    I noticed this pinging a long time ago but since it never came up on the scanner as knock retard I never really did anything about it.

    I just put my o2 switchpoints back to stock just to verify that it is pinging becuase its running leaner at lighter loads.

    But what I don't is when the tc is locked under load I don't think its in the loads where the engine is leaned out.
    I think its a wierd situation becuase the CL modes are referenced by aiflow from the map.
    So I would guess airflow would be very low at the low rpms that the tc is locked?

    This mostly happens when im hitting hills but ive also heard stock cars do this and I even read in the manuel one time not to worry if your hear slight pining when going up a hill. I also have headers which I guess might amplify the pinging but I wouldnt think so.

  2. #2
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    I just tried it again and it still knocks just as bad with 450mv in all closed loop modes. So I guess I wont worry about it and its normal?

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    Thinwall headers will amplify exhaust valve noise, and can sound like it's pinging. The important thing is, what does the scanner show? If it's knocking, then the KR will register. The only way to cure the exhaust valve noise with headers is to go with the thickest header material you can.

    The knock sensor should log a failure code unless they are turned off, might check to make sure they are enabled, reporting is enabled, and make sure the parameters are the same as your factory tune.

  4. #4
    Lifetime Member hymey's Avatar
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    Quote Originally Posted by Telco View Post
    Thinwall headers will amplify exhaust valve noise, and can sound like it's pinging. The important thing is, what does the scanner show? If it's knocking, then the KR will register. The only way to cure the exhaust valve noise with headers is to go with the thickest header material you can.

    The knock sensor should log a failure code unless they are turned off, might check to make sure they are enabled, reporting is enabled, and make sure the parameters are the same as your factory tune.
    I agree here. It is unlike it is pinging at lean cruise. Engines a low loads tend not to ping. If the car is to lean it will experience lean surging in this situation before it will ping.

    Don't rule out your gut feelings though. By all means get a second opinion. Take a mechanic for a drive.

  5. #5
    Lifetime Member Biggsy's Avatar
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    I have had audible pings with no knock being displayed on the scan tool too.

    I am running std cast headers. I know my knock sensors work, have logged KR before.
    Dave.

  6. #6
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    No KR shows in the scanner I don't even think I could get it to show at WOT even when I have very audible ping at WOT like when I don't put 93 in it.

    Im pretty sure al my settings are stock but ill check them again.

  7. #7
    Senior Member Wasted Income's Avatar
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    Quote Originally Posted by Biggsy View Post
    I have had audible pings with no knock being displayed on the scan tool too.

    I am running std cast headers. I know my knock sensors work, have logged KR before.
    Exact same thing here.
    2005 Silverado Duramax LLY - EFI Live Tuned
    1969 Chevrolet C-10 Pickup - Turbocharged 5.3L/4L80E - EFI Live Tuned
    1975 Avenger Jet Boat - 6.0L/Berkley pump - EFI Live tune in progress

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