Results 1 to 4 of 4

Thread: e40 going lean 3.2k-3.8k. HELP!

  1. #1
    Tuner in Training
    Join Date
    Jun 2019
    Posts
    15

    e40 going lean 3.2k-3.8k. HELP!

    Guys I am missing something here. I am trying to do a hybrid SD and MAF tune, similar to the way stock tune runs. For the life of me I cannot get this lean condition out of my PE WOT runs. Commanded PE is flat across the board. When in MAF only(RPM disable/reenable 200/100) AFR is good(12.5-12.8). When in SD only(failed MAF 11hz, disable/reenable 7000/6900) AFR is good(12.5-12.8). When I use both MAF and SD I go lean from like 3.2k-3.8k under WOT. By 4k the AFR seems to come back down to where it should be. I'm commanding a 12.7. Is there some weird multiplier or something I am forgetting about? I have attached my tune and logs. Thanks in advance!
    Attached Files Attached Files

  2. #2
    Senior Tuner Lakegoat's Avatar
    Join Date
    Jul 2012
    Location
    Florida
    Posts
    1,424
    Look at Fuel--Power Enrichment. You don't have PE until 5000 rpm. Make it 1500 and see what it does. Your VE table is a little rough also. I didn't look at your pedal position, so check that.
    2000 Camaro SS 2015 L83 port injected, Whipple 3.0, 4L80E, 8.8 Ford
    2013 Silverado 5.3, 6L80k 8.8

  3. #3
    Tuner in Training
    Join Date
    Jun 2019
    Posts
    15
    So I gave something a shot tonight that seemed to work for me. I zero'd out all of my prediction coefficients. I read it on some other forums and it seems to have done what I wanted it to. No longer have the lean spike.

  4. #4
    Advanced Tuner
    Join Date
    Sep 2010
    Location
    webb city, mo
    Posts
    504
    This just saved my ass as well on a E38, 2008 Silverado....had a BAD lean condition at idle. Fuel trims were 20%+ and the wideband was reading .99-1.01 lambda even it was spot-on in open loop. There was about a 5 second delay in fueling under WOT despite it commanding the PE EQ ratio. The fuel just didn't dump in until a few seconds past despite all the PE triggers and delays being adjusted....I set all the prediction coefficients back to a stock 2012 silverado ( i never changed them in the first place though???) and it fixed everything! Thanks for the post.