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4l80E weird shifting problem

Discussion in 'Chevy Trucks' started by chris694205, Feb 23, 2010.

  1. chris694205

    chris694205 Senior Member
    Messages: 175

    im having a random problem with my 97 2500 silverado... just starting a couple days ago i start it up and let it warm up, when i take off it is shifting really hard.. 1st gear through overdrive banged into gears... After driving it a couple hours it stopped... the next day i drive it somewhere and its fine.. Today it shifted hard again.. its kind of like an on and off thing.. anyone know what the deal is??
  2. jblatti13

    jblatti13 Senior Member
    Messages: 123

    ive had a similar problem, wasnt really bangin into the gears but they were rough. changed the fuel filter and problem solved. id check that out first, its a cheap part even if its not the main problem.
  3. ontario026

    ontario026 Senior Member
    Messages: 228

    do you have a decent scanner that can read enhanced trouble codes? Not just the regular codes, you must be able to read enhanced codes.... My bet is that you are showing a code 1870 when it is shifting hard, which is a trouble code for trans component slipping.... When the computer picks up on a slip rate that is too high it goes into a default mode where it maxes line pressures, etc to attempt to minimize slippage.... It will not necessarily set the engine light, I think it has to pick up on the fault on 2 consecutive trips to actually set the engine light on...

    apparently the 4L80E transmission the valve body can wear in the bore where the torque converter lockup solenoid plunger rides, causing it not to seal well, reducing the torque converter clutch grip and resulting in slippage... there is a fix I guess where they ream the bore out and install a new plunger with a teflon seal...... From what I am told there are other factors that can cause an 1870 code as well.....
    Last edited: Feb 23, 2010