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Thread: How accurate is Auto VE?

  1. #1
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    Default How accurate is Auto VE?

    So, did some logging at the base tune I was running on wasn't bad at all. This is basically just a LQ4 tune with 12.5% added to the MAF table above 5000 Hz. AFR is around 11.8-11.2 at WOT with 24-25 degrees of timing. Thought it was going to be real easy to get it dialed in at WOT, but the AutoVE doesn't seem to be accurate at all. I put it into SD mode, got several really nice logs (blew through 1/4 tank of gas) and the end result was an AFR in the mid 13s at WOT I set it up to run 12.8 at WOT in open loop. It seems like the BEN correction factor is overshooting the target AFR? How accurate have you found the autoVE to be?

    I'm attaching some tunes/logs. First is the base tune along with a log for it. The next tune is the SD tune, basically just 12.5% added to the VE table along with 12.8 commanded AFR. The first log for that tune looked okay. Log3 is the result of 2 successive logs with autoVE BEN correction factors made to the VE table. End result was AFR in the 13s. ???

    Thanks for any help.
    Attached Files Attached Files

  2. #2
    Joe (Moderator) joecar's Avatar
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    Hi GMC,

    Do you have FlashScan V1 or V2...?

    What vehicle/year/model and what mods...?

    Several things:

    - your H02Sx1 voltages show trimming... set B4206 to Disable.

    - in C6001 you have P0101,2,3 set to "Not Reported", and in log file AutoVE3.log there is no presence of any of those 3 DTC's... i.e. the PCM is still using the MAF... one of those DTC's has to be present for the PCM to ignore the MAF... in C6001 set P0101,2,3 to "A: 1 Trip".

    - at 91% injector DC, you're getting close to running out of injector, keep an eye on this, if it hits/exceeds 100% then tuning won't add any more fuel.

    - adding an initial 12.5% to the VE table might be too much (unless you have big mods).


    See if you can go thru the throttle range more progressively/smoothly... this will give you more useful data that the transient filter will keep.

    If you have a stretch of deserted safe highway, you will be able to correct the VE table in one or two passes... going uphill is good, it loads the engine more consistently.

    Be sure to apply the throttle transient filter to the BEN map before multiplying it into B0101.
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    Last edited by joecar; March 26th, 2010 at 08:22 PM.

  3. #3
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    Quote Originally Posted by joecar View Post
    Hi GMC,

    Do you have FlashScan V1 or V2...?

    What vehicle/year/model and what mods...?

    Several things:

    - your H02Sx1 voltages show trimming... set B4206 to Disable.

    - in C6001 you have P0101,2,3 set to "Not Reported", and in log file AutoVE3.log there is no presence of any of those 3 DTC's... i.e. the PCM is still using the MAF... one of those DTC's has to be present for the PCM to ignore the MAF... in C6001 set P0101,2,3 to "A: 1 Trip".

    - at 91% injector DC, you're getting close to running out of injector, keep an eye on this, if it hits/exceeds 100% then tuning won't add any more fuel.

    - adding an initial 12.5% to the VE table might be too much (unless you have big mods).


    See if you can go thru the throttle range more progressively/smoothly... this will give you more useful data that the transient filter will keep.

    If you have a stretch of deserted safe highway, you will be able to correct the VE table in one or two passes... going uphill is good, it loads the engine more consistently.

    Be sure to apply the throttle transient filter to the BEN map before multiplying it into B0101.
    Thank you very much for this reply. I'm using flashscan V1. Vehicle is a 2000 fullsize truck, 6 liter, 1 7/8 headers, 3600 torque converter, 4.10 gears.

    Regarding B4206, it's interesting they make no mention of that in the AutoVE tutorial. I followed all the instructions there to set up SD mode.

    Regarding C6001, I set all of those to not reported because it was causing my transmission to command full line pressure for some reason.

  4. #4
    Lifetime Member mr.prick's Avatar
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    You're logging 26 channels this slows the log speed.
    Log 24 channels max this will give you a little smoother BEN map for the VE table.
    Turn on PE, don't rely on {B3605} for fuel enrichment.
    {B3605} can be 1.00 EQ/Lambda @ 176F and below w/PE on.

    OL is sensitive to ECT & IAT so don't be surprised if one log is near perfect and
    the next is leaner/richer than the last.
    Using LTFTs for tuning on the streets is easier IMO.
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  5. #5
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    Got it all figured out. Thanks a ton Joe.

    Here's a log after a couple revisions today. Looks like the stock injectors are maxed out.
    Attached Files Attached Files

  6. #6
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by GMCtrk View Post
    Thank you very much for this reply. I'm using flashscan V1. Vehicle is a 2000 fullsize truck, 6 liter, 1 7/8 headers, 3600 torque converter, 4.10 gears.

    Regarding B4206, it's interesting they make no mention of that in the AutoVE tutorial. I followed all the instructions there to set up SD mode.

    Regarding C6001, I set all of those to not reported because it was causing my transmission to command full line pressure for some reason.
    For headers, 5-8% initial increase on VE table is more suitable.

    The LS1 Camaro/Firefird/Corvette calibrations all had B4206 disabled from the factory, these were that were being tuned back then, that's why the tutorial never mentioned it.

    In tables E0102, E0103, E0104 disable P0101, P0102, P0103... (they are midway down those tables).

    Again, the tutorial doesn't mention these because they were already disabled.

  7. #7
    Joe (Moderator) joecar's Avatar
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    mr.prick has a good point on 24 channels or less...

    upto 24 channels: pid update rate is 10 Samples/second
    over 24 channels: pid update rate is 5 S/s or less.

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    Is it just me or does increasing timing really affect AFR? I added 2 degrees at WOT and it went lean (12.8 to low 13s).

  9. #9
    Joe (Moderator) joecar's Avatar
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    Also, do this (unrelated to VE):
    - set D0960, D0961, D0962 to all 100%... see this: showthread.php?t=3336

  10. #10
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by GMCtrk View Post
    Is it just me or does increasing timing really affect AFR? I added 2 degrees at WOT and it went lean (12.8 to low 13s).
    Changing ignition timing can change the actual AFR... changing the timing changes the time that the mixture has to burn... (I don't understand it fully... or even a bit... )... how much oxygen is remaining at the end of the burn (this is what the oxygen sensors see)...

    timing-AFR effect depends on various things like combustion chamber design (fast-burn vs other)... some engine combinations show AFR being sensitive to timing, while other combinations show little effect.

    You now need to do a quick re-touch on your VE table... but do make sure there is no spark knock... make sure there is no KR in the log, but also make sure you don't hear any.

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