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Thread: Cold Weather Acceleration Bog

  1. #1
    Join Date
    Jun 2013
    Location
    Calgary, Alberta
    Posts
    106

    Default Cold Weather Acceleration Bog

    I know this has been brought up a few times before, but I have a couple of questions Danny. The car runs great once it hits operating temp, but until then, accelerating, especially from a dead stop, creates a bog, but not quite to a stall out. With temps hovering between 35-60° until the end of June this is a minor pita.

    I did a datalog within two minutes of startup. As soon as I did a moderate acceleration I got the bog which showed an off the chart AFR spike over 19. RPM dropped to 350 and Coolant Temp Enrichment showing about 117%. I'm going to start adjusting the Coolant Temp Enrichment 5% at a time in the affected temp range. (I had already bumped up the acceleration to 125%.) In the advance tuning section of the handheld, Closed Loop Compensation learning was disabled for starting in the temp & rpm. I enabled these. Is this a good idea? Closed Loop Compensation LEARNING now will start at 32°F & 0 RPM.

    Forgot to mention, my car is a '65 Oldsmobile Cutlass with a 5.3L LS327. Terminator throttle body. Timing run to the ECU.
    Just waiting for the car to cool down to check my adjustments, so I thought I would check in with you to get your opinion and any suggestions.
    Last edited by 442SCOTTY; 05-18-2017 at 01:44 PM. Reason: Missed the learning part

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    14,581

    Default

    Quote Originally Posted by 442SCOTTY View Post
    I'm going to start adjusting the Coolant Temp Enrichment 5% at a time in the affected temp range. (I had already bumped up the acceleration to 125%.)
    http://forums.holley.com/showthread....6649#post66649 (Coolant Temperature Enrichment % Table Tuning)
    You might also need to adjust the coolant temperature based Acceleration Enrichment parameters, especially if it's just a quick lean spike.

    Acceleration Enrichment can't be tuned until the Base Fuel Table is well tuned.
    If you have a momentary lean spike, on light throttle acceleration, check
    your AE vs TPS/MAP RoC Blanking values (in Fuel Modifiers/Fuel Control):
    If they're 15 & 7, those are the old values from the V1 ECU firmware.
    Change the AE vs TPS RoC Blanking value to 4-6.
    Change the AE vs MAP RoC Blanking value to 5-7.
    Some users reported the need for an even lower TPS RoC Blanking value.
    Ensure there's no TPS/MAP RoC signal activity at idle, due to noise/kPa fluctuation.
    http://forums.holley.com/showthread....1379#post61379 (AE Tuning Information)

    In the advance tuning section of the handheld, Closed Loop Compensation was disabled for starting in the temp & rpm. I enabled these. Is this a good idea? Closed Loop Compensation now will start at 32°F & 0 RPM.
    "Enable Closed Loop" & "Base Fuel Learn Enabled" are the only parameters that need to be check marked in Closed Loop/Learn Parameters.
    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

    New Holley Dominator ECU for sale: LINK.

  3. #3
    Join Date
    Jun 2013
    Location
    Calgary, Alberta
    Posts
    106

    Default

    Thanks Danny. Some good info as always. I will plug away at it. And I will return the two Closed Loop/Learn conditional boxes (temp & RPM) to disable as they were before.

  4. #4
    Join Date
    Jun 2013
    Location
    Calgary, Alberta
    Posts
    106

    Default

    Looking at a few datalogs that I did this morning, when the temps were about 60°, when the car bogs on acceleration the AFR spikes off the chart while the Closed Loop Compensation drops to the -40s. The coolant enrichment seems close at idle and cruise with some minor tweaking to follow. It looks like the Closed Loop Compensation Limits seem to be the problem? I lowered the Closed Loop Compensation Limits to 10%. I was going to check it again tomorrow, then hopefully lower the Closed Loop Compensation Limits to 5%. The car has a couple thousand miles on it now, so I should be on the right path. My only issues were the cold weather acceleration.

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