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Thread: Stumbling on Deceleration

  1. #1
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    Dec 2003
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    Default Stumbling on Deceleration

    Hi
    Just finished changing the motor in my 97 3500 4x4 standard.Everything went good.The doner motor came from a 97 2500, i replaced the intake with the original non egr one.Both had the same inj pump.
    I now have a hesitation/stumble when i decelerate.This happens when driving and when revving in neutral.So far there are no codes being thrown.
    Anyone come across this before?
    Thanks Thomas
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  2. #2
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    May 2014
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    us, ga
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    Default

    Did you ever figure this problem out? Thanks

  3. #3
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    Default

    Hi Aftermath
    This was a truck i got used,it had electrical gremlins.It wasn't used everyday just as required.After i changed the engine i went trough a couple of PMD's which were remote mounted,and were not Stanadyne units. Then i replace the ignition switch.Then one day i went to start it and it wouldn't fire,this was after driving it into my shop and shutting it off.By then i had accumulated everything to convert it to mechanical.I tried a few things and gave up and started cutting wires,now there is a computer living in the dash screaming away because it dosn't get any input and the truck does/did everything normal.Till the crank broke.
    So i bought a Dmax tow truck,should have bought the Dodge Cummins truck,but i am a die hard GM guy.
    Thomas
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  4. #4
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    May 2014
    Location
    us, ga
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    166

    Default

    Quote Originally Posted by Yukon6.2 View Post
    Hi Aftermath
    This was a truck i got used,it had electrical gremlins.It wasn't used everyday just as required.After i changed the engine i went trough a couple of PMD's which were remote mounted,and were not Stanadyne units. Then i replace the ignition switch.Then one day i went to start it and it wouldn't fire,this was after driving it into my shop and shutting it off.By then i had accumulated everything to convert it to mechanical.I tried a few things and gave up and started cutting wires,now there is a computer living in the dash screaming away because it dosn't get any input and the truck does/did everything normal.Till the crank broke.
    So i bought a Dmax tow truck,should have bought the Dodge Cummins truck,but i am a die hard GM guy.
    Thomas
    So I have a buddy that is experiencing a similar problem, issues on decelleration. Really nothing else I can find on this specific issue.

  5. #5
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    Dec 2003
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    Default

    Try changing the PMD
    I went through a couple of the aftermarket ones in that truck,they were remote mounted.
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  6. #6
    Join Date
    Mar 2000
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    Quote Originally Posted by Yukon6.2 View Post
    By then i had accumulated everything to convert it to mechanical.I tried a few things and gave up and started cutting wires,now there is a computer living in the dash screaming away because it dosn't get any input and the truck does/did everything normal.
    You mention it was a '97 4x4 standard - which I assumes means manual transmission? I'm curious about what else the computer controls (or tries to)? I'm thinking about MFI on my '94 and would swap in a manual at the same time, but then got to wondering what else I'd have to tinker with. ABS? Instrument cluster? Other things?
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  7. #7
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    Default

    There was nothing else effected by the swap.
    My ABS was already disabled,all guages worked fine.
    I lost the high idle through the computer,just used a manual high idle.
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  8. #8
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    Just out of curiosity, what resistor do you have on the PMD? I recall when I had a high number (don't remember if it was 9 or "13") on a pump that called for a 4, I had issues with surging just off of idle. Seems like when it transitioned from "closed throttle" to the pedal reading it gave too much fuel. I theorized it's because fuel rate at idle is based on RPM whereas off idle it's calculated, and the high number forced it to calculate a higher rate.
    The Constitution needs to be re-read, not re-written!

    If you can't handle Dr. Seuss, how will you handle real life?

    Current oil burners: MB GLK250 BlueTEC, John Deere X758
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  9. #9
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    I tested the SOL-D FSD for TDP a long time ago. When descending a grade with the cruise set and the BD TorqLoc engaged, that thing would cause the engine and truck to surge and buck violently until you turned the cruise off. I dug a little deeper and realized that the engine would hunt or surge when descending a grade with cruise off as well, it just wasn't very noticeable. The SOL-D apparently had troubles with metering fuel rate under no load situations. In fact, my negative review probably sunk that whole project.

    This never happened with a Stanadyne FSD. I would look at the FSD as a potential culprit.

  10. #10
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    Quote Originally Posted by Yukon6.2 View Post
    There was nothing else effected by the swap.
    My ABS was already disabled,all guages worked fine.
    I lost the high idle through the computer,just used a manual high idle.
    Thank you for the input. I can't say that losing ABS would necessarily be a bad thing as far as I'm concerned.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  11. #11
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    I prefer the ABS delete option myself...
    One of the joys of living here,no inspections to worry about.
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

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