4L60E woes

[avewhtboy]

I really could use some help diagnosing a transmission problem.

Background

I have an LT1/4l60 that has been running a long time.

Yesterday the transmission started not shifting gears properly.

I changed the filter and fluid still the same thing.

The thing shifts fine when cold, no problems at all, but after driving
for about 15 minutes it quits shifting properly.

What will happen, when you come to a stop the transmission is not
shifting back to low gear. I can manually shift it down and it will go into
low gear then shift to second and third but no overdrive.

Once it cools off it does that same thing over again.

When I changed the filter and fluid, it seemed fine, not burnt at all
and no metal shavings or garbage in the pan.

I did a google search and from what I read it sounds like I may have a bad shift solenoid or some other electronic issue.

I had the transmission rebuilt a couple years ago with all high performance pieces so I am hoping not to have to pull the transmission.

I was thinking it might be the torque converter, but I am really poor at diagnosing automatic transmissions.

Ideas?



I am going to try to get a computer connected to it to check whatever I can see but I think I am pretty limited with what I can see for transmission diagnostics.

Thanks

When I googled it this sounds most like what its doing...

3rd gear starts, can manually shift through all gears. When car has been turned off for a bit, then back on it will run normally.

Speed Sensor (VSS) dropoff w/ Hi-stall converter. The rpms are too high, but Speed Sensor (VSS) is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL.

Reprogram PCM for Speed Sensor (VSS) dropoff

[jbirdcamaro]

its not the converter
if it only does it after it warms up , it sounds like there might be a crack in the case or valve body. also if the speed sensor is bad it will not shift.
you could have gotton a piece of trash or something on the speed sensor, which will cause it not to read, which will cause the trans not to shift and do all kinds of stupid stuff.
i would also look at you tps sensor, it that dont work like it should, then the trans will not work either.
good luck

[avewhtboy]

I should have updated this just in case someone has similar problem. It was the alternator going bad, voltage was getting
too low to activate the solenoids.

I put a powermaster alternator on.