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Thread: Deceleration Problem

  1. #1

    Post Deceleration Problem

    Stopping for traffic light, or any significant deceleration, even at highway speeds, will almost cause the vehicle to stall. My sensor settings are good. IAC 3%, TPS 0%. When this happens the IAC goes to 0%, A/F Ratio flashes red upon acceleration. Otherwise the vehicle is running great and still in Learning mode. I thought Learning mode might correct the problem, but has made no change.

  2. #2

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    Could you upload your current tune & datalog through Dropbox? Here's a video to help: https://www.youtube.com/watch?v=rHjLwJQ45Kw
    Other than that, it sounds like you need to adjust your idle settings, which you can do better through the EFI software. But Learn mode only controls fueling.

  3. #3

    Default

    I should be able to get the datalog tomorrow. Not sure about uploading with Dropbox though. I don't use that. I'll figure something out. I'm thinking about a baseline calibration of my IAC, and try to get it more consistent from idle to idle and day to day. Sometime there are deviations of 10% to 12% from idle to next idle. I never know what it's gonna be.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
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    17,693

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    Quote Originally Posted by Cuestick View Post
    Not sure about uploading with Dropbox though. I don't use that. I'll figure something out.
    Read 3rd framed paragraph for more info: https://forums.holley.com/showthread...2178#post92178 (Useful Sniper EFI Information)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  5. #5

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    Thanks Danny. The links you provide are saved & read, and are very informative & helpful. I drove the vehicle yesterday afternoon & last night, and it did a lot better. Maybe I need to be a little more patient with the Learning mode. Will work on posting the datalog this afternoon.

  6. #6
    Join Date
    Dec 2009
    Location
    Connecticut
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    Quote Originally Posted by Cuestick View Post
    Maybe I need to be a little more patient with the Learning mode.
    In my experience, the Learning functions faster than most people think. I'd like to hear what others think of this. I realize it depends on how far off the base calibration was, and your driving ability to reach the various areas of the Base Fuel/Learn Table. One or two hours should suffice. The Learn Table is constantly changing, but when the Learn Table values stop making significant changes, the ECU is finished self-tuning.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  7. #7

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    I think part of my problem when I think about it, is 90% of my driving miles is on open highway or interstate driving, and the other 10% is say city driving (stop & go). I may need more stop & go Learning time.

    I found that I have no data files stored. I learned that I have never started datalogging. I decided that I better read up & learn what I'm doing before I mess something up. After I record & store some data files I will post. Thanks for all your help. My ignorance is coming to the surface.

  8. #8
    Join Date
    Sep 2015
    Location
    Palm Bay, FL
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    156

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    Quote Originally Posted by Danny Cabral View Post
    In my experience, the Learning functions faster than most people think. I'd like to hear what others think of this.
    I agree completely, much faster than most folks expect. I would say it learns adequately in minutes, not hours, but that's minutes per RPM/Manifold Pressure cell. If you hop in, get on an open, flat road, set the cruise control at 55 then it's going to have that cell "Learned" in minutes.

    The challenge, of course, is getting the entire table learned. When you nail the throttle from an idle (assuming you don't nail it hard enough to come out of closed loop) you go from a low rpm / high manifold pressure cell almost immediately up to a low RPM, low manifold pressure cell, and (if on a flat road) almost as quickly into a high rpm, high manifold pressure cell. You might be in any one of these cells for milliseconds.

    A best-case learning scenario is a drive on a mountainous, curvy road. You want to load the engine with a hill during acceleration so that you spend time in those quickly-visited low RPM/low manifold pressure cells. That's especially challenging here in coastal Florida. About the best we can have are bridges over the intercoastal waterway. Not much of a load.

    I find it very useful to use the Sniper EFI software while driving. This will allow you to watch where the little orange cursor is on the learn table and modify your driving to stretch into unlearned areas while ensuring you don't accelerate into open loop. Do this with an assistant driver watching the display and coaching the driver, of course. Much too dangerous for the driver to be watching this while driving.
    Chris Myer
    800-880-0960 x654
    chris@EFISystemPro.com

    Check our website for live stock status on all Holley items!
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  9. #9
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    Nov 2014
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    Ont. Canada
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    Another option is to Transfer your Learn Table to your Base Fuel Table, then manually blend in the unlearned areas. I find this helps.

  10. #10
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    Dec 2009
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    Connecticut
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    Read 4th & 5th paragraphs: http://forums.holley.com/showthread....2523#post62523 (Holley EFI Tuning Tips & Information)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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