A 4l60e that really holds
Like the man said, you're going to have to give a better description if you're going to get any help on this forum diagnosing the problem.
Remember that the PCM completely controls when the trans shifts and to a great extent how hard it shifts. However if under the same conditions some shifts are hard and others are soft (especially with slippage), this can be caused by a "sticky" EPS (pressure control solenoid, also called PCS). Several builder here have told me they not only replace the EPS with every rebuild, but just about any time a 4L60E car comes to their shop with apparent trans problems.
Once the 1-2 accumulator is out (to reduce the # washers), it is only one more bolt to replace the EPS, which costs under $30.
So I would suggest replacing the EPS and changing the 1-2 accumulator to only have one washer. Start there and tell us how that works for you.
This is no guarantee to fix your issues, but IMHO has a reasonable probability.
Well, actually the first thing you should consider is a sensor problem as this will also affect shift quality. Disconnecting the MAF is a quick way to test if the MAF is marginal. I don't recommend WOT with the MAF disconnected unless you are absolutely sure the PCM was tuned for speed density operation.
Remember that the PCM completely controls when the trans shifts and to a great extent how hard it shifts. However if under the same conditions some shifts are hard and others are soft (especially with slippage), this can be caused by a "sticky" EPS (pressure control solenoid, also called PCS). Several builder here have told me they not only replace the EPS with every rebuild, but just about any time a 4L60E car comes to their shop with apparent trans problems.
Once the 1-2 accumulator is out (to reduce the # washers), it is only one more bolt to replace the EPS, which costs under $30.
So I would suggest replacing the EPS and changing the 1-2 accumulator to only have one washer. Start there and tell us how that works for you.
This is no guarantee to fix your issues, but IMHO has a reasonable probability.
Well, actually the first thing you should consider is a sensor problem as this will also affect shift quality. Disconnecting the MAF is a quick way to test if the MAF is marginal. I don't recommend WOT with the MAF disconnected unless you are absolutely sure the PCM was tuned for speed density operation.








