1-2 shift problem 4l60e need help asap
1-2 shift problem 4l60e need help asap it seems that 99 ls1's have this common,, at wot the car will not shift into second,, it will stay in first,, but when u let go the trottle it will shift kinda lazy and will work fine,, and 2-3/ 3-4 work fine.. also when ur doing 20 and punch it and down shifts it gets stuck again,, the car is bone stock ,stock trans,converter etc,, we put a shift kit in and didnt change a bit,, anyone have any ideas, i need this car running this weekend...please help//
If the transmission will not upshift under full throttle , you first need to use a scanner and look at the data stream and see if its comanding the shift , if the pcm is not making that comand no matter what you do to the transmissions short of making it a full manual valve body is going to solve the issue , The 4l60e can only do what its comanded , On the note of it being a common problem I have not noticed or ran into this.
Originally Posted by performabuilt.com
If the transmission will not upshift under full throttle , you first need to use a scanner and look at the data stream and see if its comanding the shift , if the pcm is not making that comand no matter what you do to the transmissions short of making it a full manual valve body is going to solve the issue , The 4l60e can only do what its comanded , On the note of it being a common problem I have not noticed or ran into this.
This is the first thing to do! 
Take the advice on getting it scanned, or better yet have
someone who can edit the tune, check out what your shift
point MPH is and what you're really turning at the top of
1st. You have to separate mental from physical problems
right off or you'll buy the wrong pill and it won't do nuthin'.
someone who can edit the tune, check out what your shift
point MPH is and what you're really turning at the top of
1st. You have to separate mental from physical problems
right off or you'll buy the wrong pill and it won't do nuthin'.
