98 tahoe shifting problem

Discussion in 'GM Powertrain' started by Bobby1021, Jul 14, 2010.

  1. Bobby1021

    Bobby1021 New Member

    when ever i punch the gas my truck doesn't let me shift unless i release the gas a little bit. but it only does this when i punch it. normal city driving i dont have a problem
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Is the CEL lit?? Also try a sweep test on the TPS since that could be misreading and sending a poor signal to the computer.
  3. 97Tahoe

    97Tahoe New Member

    I have the same problem engine revs but it doesn't down shift untill I let off the gas a little
  4. trapperdon

    trapperdon Rockstar 100 Posts

    mine just took a crap on me the same way yesterday, just as i got into the fast lane of the freeway, not good !
    couldnt get it to upshift above 50 mph, had to limp it home.

    last night ( this morning at 3 am ) on way home from work it wouldnt shift from 40 mph, then when i could
    finally coax it to shift i'd get to about 56 mph and it would act like it was a manual tranny in 2nd gear at high rev...

    i am on vacation as of today, was going to replace the entire suspension & bushings and do a write up,
    but getting it to be able to drive right now takes top priority !!

    would it be vacuum lines to the tranny or would it more likely be something in the TBI or related systems
    that would cause it to fall flat and not shift?

    i'm better at helping other people with probs, i get braindead when diagnosing my own issues...
  5. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    I would do a sweep test on in the TPS, also you might have a bad solenoid on your truck.. And did the CEL come on? If it did i would pull the codes.

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