2001 Montana Ext does funny shift thing sometimes?

[fritcr]

Our Montana has about 90k on it. The tranny (sometimes) seems to sort of slam in gear. It does with going from like reverse to drive. Like when backing out of a parking spot or something. Also, from time to time it does a funny downshift thing when doing a rolling stop...ie...like crossing a double lane hwy when your in the middle of the hwy but don't have to actually fully stop. It sort of jerks into gear. This don't happen all of the time.
Here is what I have done:
I did a pan drop and put a shift kit in it from ZZP and filled it back up with new fluid. Of course that kit included a new filter. This did not seem to make any difference at all to the tranny. Maybe just a bit firmer shifting when going through the gears. I did this on the advice of someone on this site. Actually, I found most of the info on the Grand Prix site. (I also own a Grand Prix GT)
Anyway, if anyone had an idea on what might be going on let me know.
Rob

[merc81]

You are a veteran poster of some 200+ messages on this forum and you really don't know what's up with that tranny? Try here:http://www.automotiveforums.com/vbul...t=transmission
or here:


or here:

Or better yet, do a search on 4t65e transmission and see what shakes out. This is as common a problem as the lower intake gasket failure. There are a couple of guys on here that are certified asme tranny specialists and they have posted photos of the bad parts and how to change 'em out.
John

[fritcr]

No not really, not a tranny person AT ALL. I did do the zzp mod and dropped the pan...filter etc. But now have this lurching problem sometimes.
I noticed you mentioned something about the LIM gasket just noticed that is leaking too. I'm about to give on GM cars. I have has so many cars with the intake gaskets going out.
Well, the other thing I read is about this PCS selonid but it is associated with hard shifting..mine does not shift hard at all. Only on take off or when just rolling and then taking off mostly...like it can't decide which gear to go into.
Thanks for any responses.
Rob

[jwright76]

Hey Rob,
have had some experience with the 4t65e and two things that come to mind. It is common to see burnt clutches for both first and second gear. If you have access to a scanner, not the cheapy code readers as the do not always catch everything, have the transmission scanned for codes. Look for code p1811 Max adapt long shift. What happens with this code is the control module commands the transmission to shift and monitors the time in which it takes to see an rpm change (i.e. the actual gear change), if it is consistantly above .75 seconds it will set this code. Once this code is set the control module goes to a default mode and set the transmission line pressure to maximum pressure which cause mostly a hard 1-2 shift .In a nut shell , the transmission has internal worn parts such as clutches and or bands and will need to be overhauled or replaced. I have seen these with as low as 40K miles have worn parts. Good Luck