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  1. #1

    Default 98 suburuban hiccups at highway speeds

    Hi guys and gals. I have a 98 'burb that I bought new. I have had a problem for the last 1.5 years in that the truck hesitates or hiccups at highway speeds. It is like it misses one cylinder firing. I have changed the fuel pump, filter, and ran several tanks with injector cleaner thru it. It seems to be getting slowly worse. It is not throwing any codes. I have seen other posts on here about similar problems and the run from a computer reset to a failing tranny. Any more ideas to narrow down my problem with out throwing tons of money at it? Thanks for any help you can give me.

  2. #2

    Default

    What engine, how many miles, how do the plugs look, have you done a compression test.
    Just trying to get a little more info.
    2010 Silverado LT 1500 5.3L 4X4
    '95 BMW K1100LT
    '97 BMW K1100LT

  3. #3
    Jr. Engineer Jamm3r's Avatar
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    Dec 2012
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    Default

    If the tranny you will find out soon enough just by driving it....
    Minneapolis area - 1997 K2500 regular cab long bed + 8.5' Western Unimount plow + modified transmission + 2nd battery + modified camper charge circuit + 1971 Cayo camper -and- 2004 4x4 Suburban 2500 8.1 + Maxbrake controller + 2nd battery + modified trailer charge circuit + Reese receiver, pulls 30' Airstream trailer

  4. #4

    Default

    More info for you all. I had the Tranny serviced just 6 months ago. Engine is a 5.7L, all plugs recently pulled, gapped and look fine. I have not done a compression test. The "hiccupping" doesn't happen constantly, but is intermittently between a few minutes and 30 minutes. It does not matter if I have the cruise control on or off. It doesn't seem to occur when I am pulling a trailer. If I am just driving the truck without a trailer, it only happens on flat level ground at a steady speed, I have not noticed it when I am accelerating or decelerating, climbing or decending a hill.

  5. #5

    Default

    It almost sounds like a weak zone in the throttle position sensor.
    As you describe the details, the engine runs fine when you are "working" the throttle.

    "It doesn't seem to occur when I am pulling a trailer. If I am just driving the truck without a trailer, it only happens on flat level ground at a steady speed, I have not noticed it when I am accelerating or decelerating, climbing or decending a hill."

    I personally haven't gutted one open to see what is internal to them if it's an optical sensing assy or if it's a mechanical resistance wiper assy.

  6. #6

    Default

    I had not thought of the TPS switch. I will look into replacing that as I have also noticed the gas pedal sticks occasionally at idle and it have to give it a quick healthy tap to break it free then it works smoothly for awhile.

  7. #7

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    If the throttle is getting stuck check to see if the throttle plate is dirty it may be causing it to stick when closed.

    1996 Chevy Tahoe LT 5.7L V8 4X4 205,000+ miles. Built proudly at Janesville Assembly in Janesville, Wisconsin
    Basic mods: Lights all over, bunch of electrical work, and a couple cooling mods.

    Check out my other mods in My Garage: http://www.gmtruckclub.com/forum/sho...t-Tahoe-4-Door

  8. #8

    Default

    Conlan, can you tell me where the throttle plate is?

  9. #9

    Default

    Odd, I had the same issue when I was drive to and from work on Sunday. I was doing about 60ish and all of a sudden it hiccupped. Thought my tranny went out but I kept rolling. I will have to look into that as well.
    -K&N Air Filter


  10. #10

    Default

    Under the intake resonator on the top of the engine. Its the big butterfly valve that the throttle cable controls in the throttle body. Its hard to miss. Check front and back of it by moving the throttle to WOT and looking at the back side. Also even tho I'm sure your smart enough to know do this all with the engine off.

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