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  1. #1

    Default Silverado engine or tranny problem?

    Hey guys,

    New to the site, I have been having a problem with my 1999 Silverado 4x4 4.8L , Everything works fine, tranny shifts with no problems, but it seems when im driving between 40-55 mph (70-90kph) and im depressing the accelerator slowly right before it wants to shift into overdrive the truck studders or jerks alot, almost feels like a tranny slip, but my idle doesent change, could it be a bad misfire? is there an overdrive sensor of some sort? Fuel problem? , more so happens up hill. Its hard to explain, Engine idle at the time is around 1000-1500 rpm, just before downshift into overdrive. but doesent happen all the time. any info would be appreciated. Thanks

  2. #2

    Default

    Quote Originally Posted by Silver1 View Post
    Hey guys,

    New to the site, I have been having a problem with my 1999 Silverado 4x4 4.8L , Everything works fine, tranny shifts with no problems, but it seems when im driving between 40-55 mph (70-90kph) and im depressing the accelerator slowly right before it wants to shift into overdrive the truck studders or jerks alot, almost feels like a tranny slip, but my idle doesent change, could it be a bad misfire? is there an overdrive sensor of some sort? Fuel problem? , more so happens up hill. Its hard to explain, Engine idle at the time is around 1000-1500 rpm, just before downshift into overdrive. but doesent happen all the time. any info would be appreciated. Thanks
    It's probably a misfire. Drive it until it misfires and then lightly depress the brake with your left foot while maintaining the condition with your right foot. The misfire should go away when you do this. Also if you get your truck scanned you will probably see a freeze fram pending code for the misfire.
    Jim

    2004 SILVERADO 2500HD LS
    Pro Comp Leveling Kit
    285-75-16 Cooper ST All Terrains
    Pro Comp Programmer
    Bilstein Shocks
    Linux Bed Liner
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    Other rides:

    1967 Landcruiser <350 Chevy>
    1970 Camaro
    1990 Geo Metro Convertible
    2007 FJ Cruiser

  3. #3

    Default

    I will give that a shot and let you know how it goes. thanks for the help

  4. #4

    Default

    Change your sparkplugs - check wires and cap - I had the EXACT issue on my 95 burb - I swore the tranny was failing - installed new plugs and it shifts / runs like new - 198k

    ALSO make sure the plug gaps are correct - the ones i removed were waaay off .45 too large
    Last edited by jtwh20; 09-13-2009 at 05:25 PM. Reason: add gap
    burbn' in NC

  5. #5

    Default

    Thanks. do you recommend Ac Delco?

  6. #6

    Default

    I just went with Autolite - I couldn't find 8 AC delcos in a hurry
    burbn' in NC

  7. #7

    Default

    Quote Originally Posted by Jimmiee View Post
    It's probably a misfire. Drive it until it misfires and then lightly depress the brake with your left foot while maintaining the condition with your right foot. The misfire should go away when you do this. Also if you get your truck scanned you will probably see a freeze fram pending code for the misfire.
    I tried this and when i did it, it dropped to overdrive fine is this good? or a sign of something?

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