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Thread: E38 Turbo sudden odd idle behavior goes Lean backfires then recovers

  1. #1
    Tuner
    Join Date
    Sep 2015
    Location
    Iowa
    Posts
    70

    E38 Turbo sudden odd idle behavior goes Lean backfires then recovers

    This has been running pretty well and we have been trying to dial it in closer and closer. Went to run it some more the other day and it started acting funny at idle so replaced O2 on b1 because vcm scanner showed o2 voltage drop off/stick and stft's very high causing lean condition and sometimes backfire. Then b2 did it so swapped in new o2 on b2 as well and still doing it. Idles ok and then again it seems to get round 70-75kpa on pressure (coincidence idk?) and the o2 voltages drop and it leans WAY out according to our wideband and it starts chugging and backfiring and then sometimes it comes out of it and sometimes it does not. As an example you can see it do it at the 04:07:26 mark in the 19-06-18 16-09-05.hpl log file.
    I have attached a few logs and a current tune as well as the channels I am currently monitoring in the vcm scanner. Since I am limited with injectors among other things in the e38, Ive used the double stoich method to get around these limits etc. Any help would be greatly appreciated.
    Thanks
    Eli
    Attached Files Attached Files

  2. #2
    Looks like a misfire and your timing tables look whack.

  3. #3
    Advanced Tuner
    Join Date
    Feb 2015
    Location
    Perth, Australia
    Posts
    974
    your VE tables look very odd. the cruise and idle section doesn't look right.

    your MAF is not failed correctly.

    your spark corrections at idle are too aggressive