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Thread: Getting my KR under control going well, one other issue

  1. #1
    Lifetime Member Whippled 496's Avatar
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    Default Getting my KR under control going well, one other issue

    Well after bunches of help from DCJustin and 02Sierra as well as a few others, i am on the right track now with my tune. Seems my knock sensor filter was not set correctly (7.90) and needed a little time to adjust to the proper setting (4.70). Now everything in the KR separtment is looking good. Getting ready to do a MAF dial in and get my spark and IAT tables pegged down. The VE is very close with a BEN factor on average of about 0.8-1.1. And the Spark table is real close, i just want to tweak it out. My LTFT's are off some, but i will work on that too.

    The other issuse i have (not a real big deal) is when i start the truck up for the first time, i find it needs to crank a little more than it used to and its hesitant to fire right up. After its warm, it fires up with no problem at all. It seems to idle fine (warm or cold) its just that first cold start. The truck is not a daily driver, i use it on the weekends and for vacation mostly. It gets driven maybe 50 miles a week and usually just on Fri, Sat, and Sun. What do i need to adjust to get this thing to fire up on cold starts like it used to?
    2014 GMC 2500HD RCLB SLE
    LML / Allison

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    Lifetime Member Whippled 496's Avatar
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    Any ideas? Its not really an idle issue, its just the first crank up when its cold. I have not messed with any "starting/cranking, or idle" tables at all. Just struggles to start on the initial cold (first) start-up. Has to crank 3 or 4 times more than it does when its warm. When i start it up after its warm, it fires right up no problem, but when its cold, it takes a few more turns and stumbles a little for about 2 or 3 seconds before it falls into a nice idle.
    2014 GMC 2500HD RCLB SLE
    LML / Allison

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    If any tables were off, the problem would be most pronounced immediatley after a reflash, until the idle learn process compensates. It would be less noticeable on susequent cold starts. Are you running off the MAF?

    If your desired airflow/cranking/throttle area/etc. tables are still stock then perhaps there is a mechanical issue. Did you do a "summary of differences" compare of your current tune to your original tune to ensure that there were no inadvertent changes to any tables?

    Does your fuel pressure hold when the pump is not running?
    2017 Camaro SS, 2014 Ram 2500 4x4 Cummins 6.7L, 2004 Chevy Avalanche Z71 4̶X̶4̶(now 2WD), 5870lb race weight, 10.93@ 124, Twin TVS1900s, Twin Throttle, 429 LSX, 4L80E, custom 14 bolt rear, V2, R̶o̶a̶d̶R̶u̶n̶n̶e̶r̶(dead), COS3......
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    Lifetime Member Whippled 496's Avatar
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    Yes, i am running off the MAF. The problem only exists on the initial cold startup, after that, it has no problem. The only tables that were adjusted were the high and low spark tables, IAT table, VE table, and PE vs RPM table. Everything else is stock, i have been doing a lot of reflashing as of late trying to get my tune dialed in, perhaps i have not allowed sufficient time for it to learn.

    Thanks for the reply DrX.
    2014 GMC 2500HD RCLB SLE
    LML / Allison

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    EFILive Reseller kbracing96's Avatar
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    You changed out your fuel pump a while back right? could be that the new pump isn't holding pressure as long. I'd try turning the key on a waiting a second or two and then start it. Might need to repressurize the fuel system to start fast when cold.
    01 ECSB 1/2 ton 4x4 Forged 5.7 LS1 GMC

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    Lifetime Member Whippled 496's Avatar
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    Quote Originally Posted by kbracing96
    You changed out your fuel pump a while back right? could be that the new pump isn't holding pressure as long. I'd try turning the key on a waiting a second or two and then start it. Might need to repressurize the fuel system to start fast when cold.
    I never changed the pump, i dropped the tank and was going to change it but realized i would have had to hack the bucket up in order for it to work. I ended up just buttoning it back up and its worked fine since. I dont see any drop in psi at the rail according to my gauge.
    2014 GMC 2500HD RCLB SLE
    LML / Allison

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    Quote Originally Posted by kbracing96
    You changed out your fuel pump a while back right? could be that the new pump isn't holding pressure as long. I'd try turning the key on a waiting a second or two and then start it. Might need to repressurize the fuel system to start fast when cold.
    That's what I have to do with my walbro

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