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Thread: Open Loop Fault?

  1. #1
    Member
    Join Date
    Feb 2009
    Posts
    76

    Default Open Loop Fault?

    Hey Guys,

    I have been chasing a problem with my firebird.

    I run COS5 and don't drive the car very often.
    Anyway, I had my tune running well in semi open loop
    and all the sudden it started running rich.

    I thought maybe it was because the weather had
    gotten colder so I switched to a closed loop tune
    to see if the trims would resolve the problem.
    It seemed to help once it warmed up to operating
    temperature.

    Then I got a PO200 code, injector circuit issues.
    So I checked all the wiring for shorts, none,
    put an ohm meter on all the injectors, they all
    were 11.8 to 12.1 ohms. They are stock 28 lb
    injectors by the way. So then I took it for a drive
    and everything was good again.

    Next time I drove it it went back to being too rich.
    Got the PO200 code again and P1133 P1153. The P1133
    P1153 I think was because it was so rich the O2's weren't switching
    at all. It was in open loop fault at this time also
    and I'm not sure if that is related to the O2's not
    switching.

    I have not used a noid light as I don't have one and don't
    know if that would help me because both banks go rich.
    So I don't think it's one injector.

    I am starting to think it's my PCM because it seems to be
    an intermittent thing.

    Any ideas on further troubleshooting this?
    Also where is the best place to get a new PCM if I need one?

    Thanks

    Brad

    edit: I loaded an open loop tune and took 10% out of the commanded fuel and it still goes rich about the same as before.
    confused.
    Nothing has made a difference, once it warms up it goes to 12-13 AFR. HO2's read rich both banks as well as wideband even with commanded EQ at .9 using a known good calibration.
    Last edited by bmax; March 3rd, 2012 at 02:00 PM. Reason: more info.
    99 Firebird Formula, M6, LS6 intake, headers, catback, lid, BRE cam.

    EFI V2, V7.5.5 (Build 149)
    V8.1.2 (Build 142)
    Boot Block 2.07.01 Oct 14, 2010
    Firmware 2.07.05 Jan 29, 2011
    LC-1 with serial cable
    COS 5

  2. #2
    Senior Member
    Join Date
    Apr 2010
    Posts
    167

    Default

    Have you check you are not in Piston protection enabled mode or CAT protection? I noticed in the COS3 when I updated the parameters were such that Piston protection was enabled

  3. #3
    Member
    Join Date
    Feb 2009
    Posts
    76

    Default

    Thanks for the reply.

    No, that's not it. If I start it from cold and watch the wideband and the narrow bands at idle, once it warms up the A/F goes to 12.6 or so every time. Even after removing 10% from commanded.

    Does it with MAF or without, with or without trims also. Driving or idling, same result.

    I've got a replacement PCM on the way now.

    Thanks again.

    Brad
    99 Firebird Formula, M6, LS6 intake, headers, catback, lid, BRE cam.

    EFI V2, V7.5.5 (Build 149)
    V8.1.2 (Build 142)
    Boot Block 2.07.01 Oct 14, 2010
    Firmware 2.07.05 Jan 29, 2011
    LC-1 with serial cable
    COS 5

  4. #4
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Hi Brad,

    Can you post a log showing the front O2 voltages HO2S11/HO2S21...

    also include EQIVRATIO, LONGFT1/2 and others.

    [ I somehow missed this thread a week ago ]

  5. #5
    Member
    Join Date
    Feb 2009
    Posts
    76

    Default

    Joe,

    Never got any good logs as I was not comfortable to drive it being too rich. Anyway, I changed the PCM and all is well again.

    Thanks.
    99 Firebird Formula, M6, LS6 intake, headers, catback, lid, BRE cam.

    EFI V2, V7.5.5 (Build 149)
    V8.1.2 (Build 142)
    Boot Block 2.07.01 Oct 14, 2010
    Firmware 2.07.05 Jan 29, 2011
    LC-1 with serial cable
    COS 5

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