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Thread: Help with AFR swings during throttle transitions LS1 in track car - causing concern.

  1. #1

    Default Help with AFR swings during throttle transitions LS1 in track car - causing concern.

    The engine made 505 HP & 460 ft/lb TQ on the engine dyno and is:
    Stock LS1, 346 CI
    LS6 Intake
    Comp Cam
    Gross Lift .598"/.610"
    Duration @ .050" 231°/277°
    LSA 114°
    Timing INT: 6° BTDC (open) 46° ABDC (close)
    Timing EXH: 57° BBDC (open) 1° ATDC (close)
    Upgraded valvetrain

    It has been swapped into a BMW Z3 used strictly for road course racing on track never driven on the street. The car is light at 2800 lbs. The engine builder tuned the engine on the dyno and after installing into the car it has been further tuned track side. After fixing a problem with air leaking into the exhaust upstream of the WBO2 sensor due to slip on collectors by welding them sealed the car has been running well.

    The one issue that has been constant is that the AFR readings swing rich & lean during throttle transitions. This happens at any RPM/load and is a problem since in this application throttle transitions occur frequently. The engine builder/tuner and I have tried everything to rectify the problem. Most recently I've added injector phasing according to the procedure described elsewhere in the forum and extensive smoothing of the fuel maps using the VE Conversion. I've also played around with other controls including limiting learn at TPS < 20%. But nothing seems to have any impact on the issue.

    Attached is a very short datalog that illustrates the problem and my GF. At WOT and steady state throttle the AFRs are stable and the engine idles fine. Is this something I should be concerned about? If so, any suggestions on what my fix this problem would be greatly appreciated.
    07101518.zip Dan Croteau modified 7.10.zip
    Last edited by LS1Z3M; 07-11-2019 at 08:24 AM.

  2. #2
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    http://forums.holley.com/showthread....ents-Read-This (Initial Checks & Adjustments - Read Steps #1-#6!)
    http://forums.holley.com/showthread....2523#post62523 (Holley EFI Tuning Tips & Information)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3

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    I went through all of the above & more multiple times. I've been working on this for over a month now and have read all recommended readings & checked everything numerous times.
    Last edited by LS1Z3M; 07-11-2019 at 08:27 AM.

  4. #4
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    How much tailpipe do you have after the WBO2 sensor? I'd change your MAP scale to better suite your needs. A lot of wasted space there. Don't use 0 in your MAP scale. Look at your Fuel Table in VE form and you'll see why.

  5. #5
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    Yes, a lot of wasted MAP kPa resolution: http://forums.holley.com/showthread....4365#post44365 (MAP kPa & RPM Axis Configuration/Tuning Information)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  6. #6

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    Quote Originally Posted by 81 TransAm View Post
    How much tail pipe do you have after the WBO2 sensor? I would change your map scale to better suite your needs. A lot of wasted space there. Don't use 0 in your map scale. Look at your Fuel map in VE form and you will see why.
    I did smoothing in VE and noticed that, but could not figure out how to eliminate the "O" axis? Here's a sketch of the exhaust system:
    Click image for larger version. 

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  7. #7
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    Quote Originally Posted by LS1Z3M View Post
    I did smoothing in VE and noticed that, but could not figure out how to eliminate the "O" axis?
    See link in post #5.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  8. #8

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    Quote Originally Posted by Danny Cabral View Post
    See link in post #5.
    I followed the instructions below and was able to change the MAP to read from 10 to 100 kPa in my Base Fuel Table.

    MAP scale: Manually enter 10-20 kPa in the bottom cell and 100 in the top cell. Then highlight all the kPa cells by right-clicking the entire kPa column and select "Fill Column Values".

    The RPM scale can also be configured for better resolution. There should only be two columns below the target idle column and the last high RPM column should be your maximum RPM. So if you idle at 900 RPM, the RPM scale can be configured from 600-700 RPM to 6300 RPM (or whatever your redline is) for the most resolution. The 500, 600, 6500, 6750 & 7000 RPM columns are useless to me, and were a further loss of valuable table resolution.

    RPM scale: Manually enter the target idle RPM cell (3rd cell), the two cells below it and the one idle cell above it (4th cell). Next, manually enter the maximum (rev limiter) RPM in the last cell. Then, highlight the RPM scale by right-clicking on the 4th cell, all the way to the last RPM cell and select "Fill Row Values".


    However, I could only manually enter my target idle RPM of 950 into one of the cells as described (the 3rd). When I tried to enter the same value into cells 1, 2 and/or 4 the entire RPM scale changes with each entry. Or when you say manually enter values into these cells, should I be entering 750, 850, 950 & 1050 RPM into cells 1,2,3, & 4 respectively? Which produces this:
    Click image for larger version. 

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    Last edited by LS1Z3M; 07-11-2019 at 11:19 AM.

  9. #9
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    Quote Originally Posted by LS1Z3M View Post
    However, I could only manually enter my target idle RPM of 950 into one of the cells as described (the 3rd). When I tried to enter the same value into cells 1, 2 and/or 4 the entire RPM scale changes with each entry.
    What? Why would you enter the same RPM in two or more cells?

    Or when you say manually enter values into these cells, should I be entering 750, 850, 950 & 1050 RPM into cells 1,2,3, & 4 respectively? Which produces this:
    I can't see that picture detail, but here's an example: https://forums.holley.com/showthread...8640#post88640 (Target A/F Ratio Table & Base Timing Table Reference)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  10. #10

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    I thought the same that you would not, but the wording in the instructions was a little ambiguous and I wasn't sure if there was some means to populate the other 3 cells around the 3rd idle RPM with software scaled values.
    So with a target idle RPM of 950 is the following for the first 4 cells good? 750, 850, 950, 1050? Or would it be helpful to set the scale lower or higher before and after the 3rd cell?
    BTW, I appreciate your help and will go back and rebuild my GF making sure I use all of this information and suggestions in the link you provided.

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