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More O2 sensor and diagnosis

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  • More O2 sensor and diagnosis

    What a difference an operational O2 sensor has on drive-ability!

    First I should say that my parts runner is a 1993 Chevy Caprice ex police car with the 9C1 package, 5.7Liter 700R4 Throttle Body. Named Notacop.
    Basically the same GM system we use with a different computer.

    The check engine light came on and I checked it with a code reader and it had stored two codes (13 and 44) indicating a bad or faulty O2 sensor.
    From what I have read I assume the car is running in open loop as the back up program.
    I drove this way for a couple of weeks do to cold and didn't notice to much, the gas gauge seemed a little quicker?
    I got a new O2 sensor today and put it in, cleared all the codes by disconnecting the battery. Then went for a test drive. Wow! The car felt much more responsive, crisper, cleaner seat of your pants diagnosis. Lower idle at all times, much smother. I have to admit I like driving this car, it has many performance upgrades with the 9C1 package. 65lb injectors over the stock 55lb, cam, timing and fuel maps, higher and firmer shift points, sway bars, oil, trans and PS coolers etc... top speed 132 I have not seen yet and now that Montana has a speed limit I probably won't.

    Wonder what the Holley system does if the O2 sensor goes bad?
    [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

    1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

    1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

    [SIZE=3][B][URL=""][/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
    [B]May be all you need to know about EFI![/B]

    and I still help local JustIH members (for fun) free! :cool: [/CENTER]

  • #2
    On my Holley 4Di system I adjusted my fuel map so that the Closed Loop mode is adjusting the mixture back between 10% to 15%. In Open Loop the engine should then be running 10% to 15% richer than optimum. I have put it in Open Loop with the lap top and it runs OK, but not nearly as crisp as Closed Loop.