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Thread: Intermitent commanded A/F to 16:1

  1. #1
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    Default Intermitent commanded A/F to 16:1

    I have something weird going on in my tune that I have not seen before. Intermittently my commanded A/F will go from 14.64 to 16:1. I have gone thru my cal and I can not locate anything that would be commanding it to do so. My open loop commanded the entire time stay at EQ 1. What else is there that I am obviously missing that could change that commanded value? I am at an absolute loss on this one....
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    Anybody? This is happening during closed loop by the way.

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    Log and see if the PCM thinks it's in idle mode when this happens, you have the tune setup so the PCM may command 15.45:1 for certain idle conditions. Does it do it under load or just while coasting?
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

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    I have only logged it cruising above 2000rpm.

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    Where are you seeing that 15.45?

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    B3607, Fuel->Mixture->Parameters

    The log shows 1150rpms and 54-55kPa when the commanded AFR goes to 16.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

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    150 degree cruising IAT and a bunch of voltage drops below 12v..... whats going on there?

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    The engine is in a Jeep CJ which doesn't leave a lot of room for a cold air intake. It's taking in the air from behind the front fender but it also tends to get fouled by exhaust heat because my intake "box" isn't complete yet. It's also 100 degrees here in Phoenix already too. :( The voltage drops are from my Lincoln Mark VIII fan cycling on and off.

  9. #9
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by Team208Motorsports View Post
    150 degree cruising IAT and a bunch of voltage drops below 12v..... whats going on there?
    Alternator failure.
    Wiring failure (breakage).
    PCM failure.

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    Quote Originally Posted by joecar View Post
    Alternator failure.
    Wiring failure (breakage).
    PCM failure.
    I actually flashed another PCM with the same OS from a different calibration that I had and hand transferred the cal to the new file without any copying to make sure that I did not get a corrupt OS but with no change so a bad PCM is out....

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