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OBD1.5 2-Bar MAP and Wideband O-2 support

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  • OBD1.5 2-Bar MAP and Wideband O-2 support

    Got this working about a year ago now. Has only been used with a Manual Transmission, I HAVE NOT tested this with an automatic transmission, but it should support both the 4L60e and 4T60e transmissions. I would LOVE to know if it works with the Automatic transmission!

    These files are for Tunerpro V5. You'll need a normal ALDL cable to hook up with, wether you have an OBD1 connector or OBD2 connector.

    If you select 2Bar Map, then it WILL NOT work with a stock 1Bar Map sensor.

    If you enable the Wideband O2, it is a LOGGER INPUT only! The PCM does nothing with the value except pass it to the ADX so you can datalog it. It does require hardware modification, you will need to add two resistors and a wire to an unused pin on the Blue PCM connector, and will need to desolder, lift and resolder a pin on one of the 68 pin CPU's on the same board as the blue connector. It's not a beginner modification, you need to be very good with a soldering iron or you can break the pin off the CPU. If you break the pin off, the PCM will still function like it did before, but you won't have any way of getting the wideband signal into the PCM. I'll update this thread with instructions for adding the wideband input. Even with the wideband added, the PCM still uses the stock O2 sensors for control.

    These patches will work with any of the OBD1.5 bins, but here are some tips for the RWD crowd:

    Use the F-body bin for RWD. It will already be setup for the Camaro T5 or 4L60e, and will need the least tweaking.
    Copy in the fuel and spark tables from an L-body bin if using aluminum heads, adjust for your displacement.
    If using an S10 T5, use the L-body values for the speedometer constants. I don't understand why the F-body T5 constants don't work, but they are WAY wrong...The L-body is within 5MPH.
    This code should work as-is for turbo use. For supercharger use, it works fine-but still needs a Take-Fun-Out table for boost control. (The L67 PCM's table for boost control is labled TKFUNOUT)

    Any questions, please ask here, or over on Gearhead EFI.
    Attached Files

  • #2
    Tried to put this up over at as well-apparently I am not allowed. The post was deleted almost immediately so who knows.


    • #3
      Updates to this:

      It's been a while since I worked with this at all, and as soon as I can "get the band back together" I am spending some time on adding in the boost control table and figuring out why sometimes the A/C gets disabled while driving in certain conditions. I don't know if anyone here has used the OBD1.5 computer for anything but if anyone has used these mods with an automatic transmission, I'd be very interested to hear how it went.