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Thread: MAP sensor oscillation at key on. P59 3 bar SD help! (Lengthy Post Pics/video/tune)

  1. #1
    Potential Tuner
    Join Date
    May 2018
    Posts
    4

    MAP sensor oscillation at key on. P59 3 bar SD help! (Lengthy Post Pics/video/tune)

    First go around with starting from scratch switching an 03 Tahoe P59 ecu to 3bar SD OS. I used Matt Happell's Colorado base tune (this combo is almost identical to the latest version of the Colorado) to get started. This is using a DBW P59, modified stock harness (MAF removed, stand alone IAT, and O2 sensors removed).

    We had a good deal of trouble at first start up and had no throttle. Changed TAC module, TB, pedal assembly and finally the ECU (First ECU used was an 04 Silverado dbw P59 from a nasty rollover). The ECU change finally gave us throttle response, but had the MAP sensor oscillation with both ECUs. We tried 2 separate MAP sensors to try to rule that out as well. All wiring has been checked for continuity, checked and double checked pin locations from ECU to sensors, checked voltage drop on all wires, checked grounds, and even completely rewired the MAP sensor circuit.

    Pulled up the scanner and first thing I noticed was an odd MAP/Baro oscillation from 0 to 100 kpa. Once started, the MAP reading levels out and moves around between ~88-92 kPa at a very crappy idle.

    This is using the ZR1 3 bar map sensor with the linear and offset at 312.50 and -11.25 kPa.

    Having doubts about being able to carry on with the weird MAP sensor issue, for shits and giggles, I tried to get the thing to go into SD and fail the MAF to see if I could get it to idle half way decent and take any sort of throttle without stumbling or stalling.

    I set the P0101, P0102, & P0102 to MIL on first error (leaving the SES Enable boxes checked) and tried to either zero or disable MAF associated tables. * See Pic Below

    With the scanner I was getting P0102, P0103, P0106, and P1514.

    ANYONE SEEN ANYTHING LIKE THIS? ANY IDEAS?

    20180506_184048 (1).jpg

    20180506_181715 (1).jpg

    20180506_183951.jpg
    I've maxed out and tried zeroing this table
    20180506_184014 (1).jpg
    Used the values from the base tune
    20180506_184026 (1).jpg
    Tried zeroing these tables to lose the P0106/P1514
    20180506_183820 (1).jpg

    20180506_183658 (1).jpg

    Attached Files Attached Files

  2. #2
    Potential Tuner
    Join Date
    Oct 2013
    Posts
    1
    did you find out why the signal was oscillating?
    I am seeing the same issue on a 2000 vette with a 2 bar sensor. I wired in a 3 bar sensor (older gm style) and also see the oscillation... so it is not the sensor.

  3. #3
    Tuner in Training
    Join Date
    Dec 2006
    Posts
    34
    It’s the scanner. It’s been doing this for a while on 2/3 bar. A few years. Plug in any other scanner and it doesn’t happen. See it on etc% sometimes too koeo

  4. #4
    Advanced Tuner
    Join Date
    Feb 2017
    Location
    miami
    Posts
    559
    when you say any other scanner, you mean another computer with the same scanner software installed?

  5. #5
    Tuner in Training
    Join Date
    Dec 2006
    Posts
    34
    No any scanner but hpt