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Thread: Dies On Deceleration

  1. #91

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    I can't check it right now, but what would an appropriate APPROXIMATE A/F Ratio be for light acceleration with this motor?
    408 stroker. Camshaft is 230°/236° @ .050" duration, .600" lift, 112° lobe separation.

  2. #92
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    Quote Originally Posted by Texasdoc View Post
    I can't check it right now, but what would an appropriate APPROXIMATE A/F Ratio be for light acceleration with this motor?
    You're the only person that can answer that, because it varies greatly.
    Read pages 4-10 of this Edelbrock EFI tuning manual, it's very good:
    https://edelbrock-files-v1.s3.amazon...ers-manual.pdf
    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. #93

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    Is there any way to flip the X-axis on the datalog graph? I keep looking at AFR Left vs Target AFR. For some reason, my brain can't seem to remember that down = rich. I keep thinking it is "quantity of fuel injected", not A/F Ratio. I keep making adjustments based off what I see in the datalogs, just to remember later that I just made things worse because down = rich. I'm going to try to add a little fuel throughout the light acceleration area. I think my Target A/F Ratio is a little lean.
    Last edited by Texasdoc; 02-29-2016 at 10:27 PM.

  4. #94
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    Quote Originally Posted by Danny Cabral View Post
    Yes. When the engine is well tuned, users typically set the Advanced Control to "3" or "4".
    That's actually backwards. When the engine is well tuned, you want to decrease the Advanced Control number, so that the engine can't overshoot too far too fast. The higher the number the faster it responds, which is good for a new tune where the fuel is likely nowhere close to being correct.

    When it's fully tuned you should drop your "Advanced Control" to 1 or 2, and you should lower your Learn Gain as well.
    This will result in a more stable tune through various driving conditions.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  5. #95
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    Quote Originally Posted by Texasdoc View Post
    Is there any way to flip the X-axis on the datalog graph? I keep looking at AFR Left vs Target AFR. For some reason, my brain can't seem to remember that down = rich. I keep thinking it is "quantity of fuel injected", not A/F Ratio. I keep making adjustments based off what I see in the datalogs, just to remember later that I just made things worse because down = rich.
    Unfortunately, there's no way to flip the value the other way.
    It's always lower values at the bottom and higher values at the top.

    However, you can just create a Math Channel that will help you with what you're used to seeing.
    Make a Math Channel called AFR Error (Left/Right/Average, make one for each if you want).
    Then set it up like this:
    100 * ( [AFR Left] - [Target AFR] ) / [Target AFR]
    100 * ( [AFR Right] - [Target AFR] ) / [Target AFR]
    100 * ( [AFR Average] - [Target AFR] ) / [Target AFR]
    This value will tell you how much fuel you need to add or subtract as a percentage.
    Negative numbers mean you need to take away fuel, positive numbers mean you need to add fuel.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  6. #96
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    Quote Originally Posted by Danny Cabral View Post
    Yes. When the engine is well tuned, users typically set the Advanced Control to "3" or "4".
    Quote Originally Posted by S2H View Post
    That's actually backwards. When the engine is well tuned, you want to decrease the Advanced Control number...
    Yes, I realize that, and I should have explained myself better. At the time, we were trying to resolve his idle & off idle issues.
    Initially, if the Closed Loop Advanced Control (1-5) is set too high, it can sometimes inhibit Learning, or cause idle problems.
    I should've said, "When the idle is well tuned, you can set the Advanced Control back up to "3" or "4" to finish self-tuning".
    http://forums.holley.com/showthread....ension-Harness (More info under "Wideband O2 Sensor Notes".)

    When it's fully tuned you should drop your "Advanced Control" to 1 or 2, and you should lower your Learn Gain as well.
    Yes, I have done so on my engine.
    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.

  7. #97
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    The Learn Gain is what determines how fast it Learns.
    All the Advanced Control does is tell it how fast to correct the AFR, and it varies depending on RPM anyways.
    All the Advanced Control settings are fast enough a few hundred RPM above idle, it really only affects the lower rpm end of the scale.
    Once it's above 2000 RPM, you won't be able to see a difference in how fast/slow Closed Loop Compensation corrects.
    And none of those values have any effect on how fast it Learns.
    Learning is all controlled by the Learn Gain percentage 0-100%.
    The higher that percentage value, the faster it will "Learn".
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  8. #98

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    Quote Originally Posted by Texasdoc View Post
    I'm going to try to add a little fuel throughout the light acceleration area. I think my Target A/F Ratio is a little lean.
    This helped a lot! Still a little hesitation under light throttle, but better. I did a datalog just driving around town. I paid attention to cruise & light acceleration in the datalogs, and where they fell on the Target A/F Ratio Table. There are basically two cell rows that hold this data. The upper one is light acceleration, the lower one cruise. I set the upper row to be moderately richer than the lower row. Now, cruise still seems fine, but acceleration is better.

    I've decided that the Closed Loop Compensation Limits table & Learn Compensation Limits table don't have enough resolution. One cell goes from 875 RPM to 1750 RPM. I idle at 950, so this needs to have Closed Loop Compensation Limits set to 5% in the idle area. I frequently cruise at 1500 RPM at 1% TPS, which is in the same cell. So I cannot set my Closed Loop Compensation Limits % any higher for cruising.

    Plus, having the Closed Loop Compensation Limits at 2% in the cells that the motor passes while decreasing RPM, is what fixed my return to idle bog. When I limited it to 2% along this path in the 875-1750 & 1750-2625 columns, the original problem (the title of this thread - "Dies on Deceleration") went away.
    Last edited by Texasdoc; 03-02-2016 at 07:41 PM.

  9. #99
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    I found my IAC Hold was set at 30%. I reduced this to 5%, which seems to have helped the return to idle, and now hold at low revs (1100-1200-1300) etc., without fluctuating. Is this related, and does this mean something else is wrong?

  10. #100
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    Quote Originally Posted by CK & his '55 TBird View Post
    Is this related, and does this mean something else is wrong?
    Yes, you shouldn't need to practically disable the IAC Hold. Try this procedure from the "F1" Help Menu:

    IAC Ramp Down Parameters
    There's an easy way to set these quickly. Perform the following:
    • With the engine at operating temp and in neutral, determine the engine speed where you want to start the IAC ramp-down (for example 1500).
    • Set the engine idle speed to this speed (1500 for this example). Look at the position of the IAC when the engine is running at 1500. For this example, it is 38 (then set the idle speed back to the normal value).
    • Subtract 5 from this value and enter that value for the “IAC Hold Position” (38 – 5 = 33 for this example).
    • Subtract the target idle speed from the ramp down speed above (in this example 1500 – 800 = 700). Enter this value (700) for the “RPM Above Idle to Start Ramp.
    • Then enter a “Ramp Decay Time” as desired. A larger number will take longer to set the engine back to idle speed, a smaller one will return it quicker.
    Performing this method will optimize these parameters.

    If these values are not set correctly, it can cause the IAC to not “count down” and return back to idle. If this is the case, either one of the following needs to be done:
    • Lower the “IAC Hold Position”.
    • Raise the “RPM Above Idle to Start Ramp”.
    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.

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