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Thread: VE table values well over 100

  1. #21
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    Dang it, I didn't even pay attention to that. Yeah I unplugged the MAF thinking the IAT was separate. I'll plug it back in and give that a whirl. Thanks.
    98 Corvette Coupe - Texas-Speed 408ci iron block, PRC 237cc heads, Ed Curtis Cam 239-247-115 .624-.624

  2. #22
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    Well that definitely fixed that issue. The car will idle if I keep my foot on the pedal a bit but obviously the afr is way off because when commanding 14.7 the WB was in the lower 12s. Overriding it to 18:1 it idles at upper 14s afr and I can take my foot off but my fuel trims are doing nothing, just staying at zero. Is that what they are supposed to do and I missed that somewhere? At this point do I just use the wideband reading vs commanded to make the adjustments? I really need to upgrade to pro to make this easier.
    Last edited by animuL; 04-08-2014 at 07:53 PM.
    98 Corvette Coupe - Texas-Speed 408ci iron block, PRC 237cc heads, Ed Curtis Cam 239-247-115 .624-.624

  3. #23
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    Am I missing something. I have always put my '02 Z06 into SD by setting the MAF to 0 and copy the HO spark to the LO spark table and it sets the P0103 right away. Do the earlier LS1's require more to go into SD.
    Bryan

  4. #24
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    Thanks to all who have chimed in, things seem to be working the way I expected now and I've made major progress in SD mode. One thing I wanted to see if anyone can confirm: when failed into SD mode the only airflow table used is the secondary VE, is that correct? In other words, the primary VE table is not used in SD mode?
    98 Corvette Coupe - Texas-Speed 408ci iron block, PRC 237cc heads, Ed Curtis Cam 239-247-115 .624-.624

  5. #25
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    Quote Originally Posted by animuL View Post
    Thanks to all who have chimed in, things seem to be working the way I expected now and I've made major progress in SD mode. One thing I wanted to see if anyone can confirm: when failed into SD mode the only airflow table used is the secondary VE, is that correct? In other words, the primary VE table is not used in SD mode?
    Yes.

  6. #26
    Advanced Tuner JamesLinder's Avatar
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    Tune for 408 Stroker

    I replaced the LS1 in my 2000 Camaro with a TX-Speed & Perf. 408 stroker. Here is a tune
    I dialed in with wide band oxygen sensor and the tune is spot on, polished over several months
    during both cold and hot weather. Let me know if you need any help!

    Specifics on my build:
    Custom Built, Forged 408 CID LQ9 - TX Speed & Performance
    (thank you Gary Luther)

    WiseCo 4.030 -8cc Pistons, Lunati Rods, 24x Lunati Crank
    199-AsCast, Precision Race Components cathedral cylinder heads 68cc; 10.7:1
    TSP Custom Order Comp Cams: 227/235 .614/.621 on 112LSA
    GM LS7 hydraulic lifters; 1.7 ratio GM shaft rocker arms with trunion upgrade
    PTM 102mm Throttle Body; Fast Toys 104mm Air Cleaner Lid with ram air hood
    FAST 102mm Cathedral-Port Intake Manifold (146302)
    TSP 100mm MAF, 2006+ Corvette Z06 GM MAF Sensor (recalibrated IAT)
    Bosch 41.7 lb/hr at 4 bar fuel injectors #0280155811
    Kooks Long-Tube headers with Y-pipe; CATs removed
    GZ Motorsports LSX Series Sportsman Crankcase Vacuum Pump Kit
    Meziere 680-WP319S Electric Water Pump
    Racetronix Fuel Pump Kit (255L/Hr integral Walbro pump)
    2000 Camaro OEM PCM (GM service code 09354896)
    Manual-Shift 4L65E Level 5 Transmission & 2400 billet converter (PATC)

  7. #27
    Advanced Tuner JamesLinder's Avatar
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    Just fyi, after finishing tuning the VEs and the MAF I left the PCM in open loop because closed loop reduced performance.
    IMO this is because the location of the narrow band oxygen sensors in the headers is not appropriate for the closed loop
    to operate properly. I do not recommend using SD tunes because a properly tuned MAF is unbeatable, especially when
    backed up by properly tuned VE table for dynamic air requirements. If tuned spot on, closed loop is pretty much
    redundant anyway. If you are in doubt, after tuning try both open and closed loop and use whatever the motor likes
    best. And, I would never tune using fuel trims; wide band is only way to go; fuel trims simply are not precise enough to
    be worthwhile IMO.

    I meant to mention that for some of the older PCMs like mine, the VE values do not adjust for an increase in cylinder
    displacement values entered. This is why on older PCMs the VEs in the peak RPM range are going to be greater than
    100% for modified motors. Although I have not worked with the newer PCMs, it is my understanding that they may
    adjust VEs when you update the cylinder displacement parameter. It really does not matter if you simply tune until
    you have zero lambda error in both VE (SD) and MAF modes. The VEs will be "correct" when you have zero Lambda error
    in Speed density tuning mode. Be sure and ask if you do not know how to set the PCM in MAF-only and VE-only tuning
    modes, or you are really wasting your time otherwise.
    Last edited by JamesLinder; 04-14-2014 at 03:38 PM.

  8. #28
    Advanced Tuner JamesLinder's Avatar
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    That is correct. Only uses secondary table so you are losing resolution and without MAF you are also losing automatic adjustments
    for air density due to inlet air temperature differences. You SD tune uses same air mass assumption for 30 degree winter air and
    100 summer air, which is of course extremely WRONG.

    Quote Originally Posted by animuL View Post
    Thanks to all who have chimed in, things seem to be working the way I expected now and I've made major progress in SD mode. One thing I wanted to see if anyone can confirm: when failed into SD mode the only airflow table used is the secondary VE, is that correct? In other words, the primary VE table is not used in SD mode?

  9. #29
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    Quote Originally Posted by JamesLinder View Post
    That is correct. Only uses secondary table so you are losing resolution and without MAF you are also losing automatic adjustments
    for air density due to inlet air temperature differences. You SD tune uses same air mass assumption for 30 degree winter air and
    100 summer air, which is of course extremely WRONG.

    Thanks for all the info. It sounds like we have a fairly similar setup so I'm interested in taking a look at that tune to see if I am changing the same parameters. I did order pro so won't be messing with my tune until that gets here. What you say about Fuel Trims makes complete sense to me since they are based on narrow band readings. From what I have heard they are quite accurate at lambda but drop off fairly quickly from there. I suppose that's why they aren't used to alter WOT fueling? Once pro gets here I'll continue following the help section guide and get the VE tuned in then move over to the MAF tuning.
    98 Corvette Coupe - Texas-Speed 408ci iron block, PRC 237cc heads, Ed Curtis Cam 239-247-115 .624-.624

  10. #30
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    I guess this goes w/o saying but upgrading to Pro and following the SD Tuning guide in the Help menu is solving all my tuning woes.
    98 Corvette Coupe - Texas-Speed 408ci iron block, PRC 237cc heads, Ed Curtis Cam 239-247-115 .624-.624

  11. #31
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    Quote Originally Posted by JamesLinder View Post
    Just fyi, after finishing tuning the VEs and the MAF I left the PCM in open loop because closed loop reduced performance.
    IMO this is because the location of the narrow band oxygen sensors in the headers is not appropriate for the closed loop
    to operate properly.
    Have you ever tried to tune "Closed Loop Integrator Delay"?

    To me that sounds like a parameter reflecting how far narrowbands are from the cylinder.

    From the Gen IV section:

    http://www.hptuners.com/forum/showth...tegrator-delay

  12. #32
    Advanced Tuner JamesLinder's Avatar
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    I have not, but it might allow one to return to closed loop operation with long tube headers without negatively impacting
    performance.

    Even in the best case scenario I would doubt that even if the delay is dialed in perfectly it would improve performance over
    running open loop with the MAF and VE's dialed in perfectly. I believe closed loop comes in handy because GM mass produces
    motors and does not have to bother to tune each one individually if they run them closed loop which in essence adjusts for the
    individual differences in volumetric efficiencies of each motor from the benchmark motor they use to develop the tune.

    Beyond this, as the motor becomes old and loses efficiency (40,000 miles or more) then closed loop adjusts for this, however on
    a performance motor I plan to tune mine annually to see if anything is changing enough to require adjustments. Tuning has become
    part of the enjoyment of owning a performance LS motor!