Page 4 of 19 FirstFirst ... 2345614 ... LastLast
Results 31 to 40 of 182

Thread: Big off idle stumble, whatt first? IFR? calc.vet? Something else I'm missing?

  1. #31
    Lifetime Member
    Join Date
    Aug 2013
    Posts
    735

    Default

    The blower is a load on the engine.

  2. #32
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    Probably not much with the bypass valve open, but you do raise a good point. Also realized I never raised idle timing with high octane timing and there's a huge gap. This may help the engine idle with less effort since it's now an issue for me. I found that idle writeup for cammed cars. Even though mine's not cammed to the point of lope, there may be some good nuggets within for me. I'll go slap that new IFR in there for now. Not sure if I should bump that idle timing table though? I realize I want it somewhat in the middle as the PCM uses timing tweaks as a way to control idle speed in addition to the IACV, correct?
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  3. #33
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    I just glanced at the VET values in my logs and they approach 2.0 on the cells with higher counts. I had to have fvcked something up on that 2 bar swap. Trims aren't maxxed out though, but a VET and SELBEN value of 2 just seem wrong don't they?

    EDIT: Perhaps I should first apply that pesky filter.
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  4. #34
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    So I'm glossing over the tutorial again and noticed that, for 2 and 3 bar applications, the MAF must be disabled. Doh! Thought it could be left in there and that it had to since spark uses the MAF. So without the MAF then the PCM just uses MAP and IAT to determine air density and airflow?
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  5. #35
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    COS uses spark (HO/LO adaptive) regardless of MAF or SD.

    Start with your objectives, which one of these is your intent:
    1. to correct MAF using WB...?
    2. to correct VE using WB...?
    3. to correct MAF using WB and LTFT...?
    4. to correct VE using WB and LTFT...?

    Note that 1 and 2 require disabling CL and trims, and disabling the other air source.

    Note that 3 and 4 require disabling the other air source.

    In all cases you correct the air source and (if you wish) you calculate the other air source (... noting that CALC.MAFT requires the OS to support the pid GM.VETABLE_DMA)... note the distinction between "correcting" and "calculating".

    If you pm me your phone # I call walk you thru it tomorrow sometime.

    ~ posted by phone ~
    Last edited by joecar; June 29th, 2017 at 09:05 AM. Reason: typo

  6. #36
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    Thanks Joe, I don't think I want to waste your time until I've actually tried and failed. I have a full tank now and fully intend to try this this weekend.
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  7. #37
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    W02LAM1 is pegged at 1.701 whether it's plugged in or not. I won't get anywhere until I figure this one out. What a fuckin waste of gas. Going through the tutorial again now. This explains the VET values of 2+.
    Last edited by Supercharged111; July 2nd, 2017 at 09:50 AM.
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  8. #38
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    Alright, seems I'm a retard on multiple accounts. I made questionable progress on the VE map but feel pretty good about the MAF. I didn't really get enough data to do VE because I didn't want to take another 45 minute hike only to have screwed something else up again. I started the day by flashing what I believe to be accurate IFR data and then proceeded to log for the calc.vet. I had trouble smoothing the map and eventually said screw it and just flashed what I had. I stopped short on the MAF so I took the highest cell I had and pasted that data into the remaining MAF cells. I noticed that the values pegged before the MAF frequency did. This is all unchartered territory for me. On the way back the logs indicated that the MAF data I changed based on logs seemed to be closer, and the stuff I guessed on just needed a little more. The thing I didn't realize about VE all this time is that it's your new value, not a correction factor like AutoVE or the MAF data in calc.vet. Derr. Anyway, Log 9 is the log I used to make my 1st change and Log 10 shows the result of that change. Tune V5 is with the IFR change and V6 has the changes I made. Because I filtered out data below 800 RPM my stumble isn't gone. I really think if I were to change the VE below 800 that I could fix that damn stumble. Do you guys have any tips for VE smoothing, guesstimation, or any other trickery to make the truck do what you want? Are my VE correction values way out in left field? Does it look like I'm bending this stuff all around an IFR that is mathematically correct but otherwise wrong?

    Whipple Log 9.efi
    Whipple Log 10.efi
    411 Whipple V6 CALCVET1.tun
    411 Whipple V5 IFR 4.8988.tun
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  9. #39
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    Sat down today with a cup of coffee and took a guess and smoothed things out and fudged to the best of my ability. Now to see if it helped. I didn't touch the MAF, it's going to peg by 11000 by the looks of things though. Is that weird? Do I have my IFR wrong somehow? I suppose I can go measure actual fuel pressure to see, but I'm not sure how accurate it'll be at altitude. I guess just add 3 to whatever I see to have my sea level value.

    411 Whipple V7 CALCVET1 With Fudging.tun
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  10. #40
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    Alright that tune did NOTHING to fix my stumble. I guess I'lm search for an idle VE tuning tutorial. I'm running out of ideas here.
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

Page 4 of 19 FirstFirst ... 2345614 ... LastLast

Similar Threads

  1. Replies: 83
    Last Post: September 5th, 2023, 11:30 AM
  2. Replies: 4
    Last Post: September 11th, 2013, 02:38 AM
  3. Big VE Difference Between AutoVE & Calc.VET
    By tinindian in forum Gen III V8 Specific
    Replies: 6
    Last Post: May 9th, 2013, 01:33 AM
  4. Calc.VET, VET Map Average is all 0.0?
    By n8dogg in forum Gen III V8 Specific
    Replies: 3
    Last Post: July 15th, 2011, 01:20 PM
  5. Slight stumble at idle (intermittent)
    By frcfed347 in forum E39, E80, E82 & E92 SIDI ECM's
    Replies: 2
    Last Post: May 25th, 2011, 10:17 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •