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Chevy 2500HD engine/transmission skip

dayjdayj Posts: 5
edited February 9 in Chevrolet
I have a 2002 2500HD with Allison transmission and the big engine 8100V8. There is a noticeable skip in the truck whenever I am in a slight pull. When serviced, I was told the truck engine checked out OK, but I know there is a problem. I'm also told that there may be a program 'fix' that may be available. Has anyone else had a problem and what is the remedy?

Comments

  • 0patience0patience Posts: 1,542
    My crystal ball cracked, so I have a hard time knowing for certain what we are working on. Dodge or GM?

    Is the Check engine light coming on when this happens? If so, what are the trouble codes?
    Are you certain that the trans is slipping?
    Have you actually seen it on the tach?
    Or are you hearing it?
    If you are hearing it, it is the radiator fan engaging.
    What do you mean a noticeable skip under a hard pull? When you get into the throttle? When you first pulling a hill? Be precise.
    It is not likely there is a trans proble, unless you have failed to service it correctly or the PCM has the incorrect calibration.
    A flare on an Allison is either one of a few things, low trans fluid, a sticking control valve, low main pressure, a problem with the speed sensor signal or a PCM miscalibration.
    No matter what it is, it is a dealer problem and should be a warranty deal. Tell them that there is a problem and they need to reflash the PCM.
  • dayjdayj Posts: 5
    Thanks for the response. The truck is new, the problem began when driven off lot. Foolish on my part but truck was transfered from another dealer and was purchased before I drove it. On a 3/4 ton the supension is stiff and the skip is like road bumps. Doing around 60, it is most noticable. I mentioned transmission since in the shop the motor checks out OK. It's on the road, maintaining 60 or in a slight pull up hills or gaining speed. It's a single skip every 2 seconds or sooner. No RPM change noticed.
  • dayjdayj Posts: 5
    Next installment. The dealership now has plugged in a unit called a 'snap shot' to record when and what conditions occurred when the engine skipped. But they also say that because the engines are now controlled by computers, they may not be able to do anything; just live with it because the problems now becomes a characteristic of the combination of engine and allison transmission. If all 2500HD's skip (a lot), then GM has a major problem that they need to solve. Any suggestions?
  • swschradswschrad Posts: 2,171
    there would be a hue and cry if they all skipped
  • 0patience0patience Posts: 1,542
    Want to call their bluff?
    If this was something that was happening to all 2500HDs with the Allison trans, then there would be an information bulletin issued to the dealer. Basically, it explains what to tell the customer when they complain.
    Ask the dealer what information bulletin told them that, because if what they are telling you is fact, there will be an informational bulletin on it.
    If they give you some song and dance about it being too new, that aftermarket systems won't have it listed, then call your customer service toll free number in your owners manual and explain to them that they are not being truthful to you and if what the dealer is telling you is indeed fact, you would like to know the information or technical bulletin number that states that. If they give you a number, (the first set of numbers will be 00 or 01 or 02) let me know what it is and we can take a look at it here.
    Here is the informational bulletins for the trans and driveability issues released by GM for your vehicle.
    #01-07-30-031 Info - 1-2, 2-3 or 3-4 Shift Characteristics During Cold Weather Operation on 4L60-E or 4L80-E Transmission - (10/09/2001)
    #01-07-30-030 Info - Diagnostic Information on Harsh 1-2 Upshift - (10/09/2001)
    #01-07-30-043 Info - Diagnostic Tips for Slipping or Missing Second, Third and/or Fourth Gear - (12/17/2001)
    #01-07-30-042 Informaiton on 2-3 Upshift Clunk Noise - (12/18/2001)
    #01-07-30-041 Info - Transmission Fluid Leak Diagnosis - (12/18/2001)
    #02-07-30-011A Info - Diagnostics for Possible Gear Indicaor (PRNDL) Concerns (Blank PRNDL DIsplay, Flahsing PRNDL, Slow or No Engagement of Automatic Transmission, DTC U1000 or U1024 Set) - (05/22/2002)
    #02-07-30-028 Info - Automatic Transmission Serial Number and Site Code Locations - (06/13/2002)
    #02-07-30-032 Info - Allison Transmission Control Module Fast Learn Procedure Update Required After Transmission Repairs - (09/16/2002)
    #99-07-30-016A Info - Diagnsotic Information for Intermittent Transmission Downshift, Slip, Busy/Cycling TCC or Noisy Cooling Fan - (09/16/2002)
  • dayjdayj Posts: 5
    The snap-shot did not show a engine skip. They are now going to set it to track the transmission. They are saying that they believe it is a problem between low RPM's and high gear/transmission ratio. IF it is, they are also saying that they will have to wait on a decision from GM even though they know there is a problem. As of now there is no bulletin on the problem, just hear-say from another dealer.
  • gdblakegdblake Posts: 18
    I've just returned from a 6200 mile pull of a 9000 lb.- 5th wheel trailer with a 2500HD CC, SB, Duramax/Allison. While on some rough roads in Michigan, do to the spacing of the expansion joints on the interstate (and the particular wheel base of this truck), the truck violently jerked (loped) back and forth during a stretch of hard pulling on this road. Never had anything like this with my previous Ford. After a change in road--no more jerking. Got me--Is this similar to what you are questioning?
  • dayjdayj Posts: 5
    No, this is more like a motor skip, bad points or incorrect timing in older engines. Last week the dealer pulled the gas tank and cleaned gas lines and injectors. No help. This week the GM engineer is going to be here and check it out. I'm afraid that they will say that this is just the way it is and I will have to live with it. That's when I exit chevy and go to a Ford, or find out how 'arbitration' works.
  • jolly4jolly4 Posts: 1
    Have heard problems with engine at 60,000miles because of bad heads. Any information on this would be appreciated.
  • I have a 95 chevy cheyenne 2500 5.8..I feel wat seems like a tranny slip. When i drive off from a start my truck feels like its lagging tryin to get out of first gear then I get big jerk like I ran over a bump..it felt like it finally got out of first gear then the check engine light comes on..but after I parked the truck drove it again no check engine light and no violent jerk feeling..any suggestions what it may be? Thnx

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