95 Base 3100 4T60E Shift/Engagment Issues

[UncleFluffy]

Hey all

I'm new to the forum but been a 'Retta fan for over a decade and a half. I have a '95 Base 3100 with the 4T60E transmission or "Loretta" as the wife and I have named her. Been a great car for the 3 years we've had it but over the last year and more over the last few months she's starting to develop some issues which is to be expected seeing as how she's pushing upwards of 300K. My biggest concern at the moment is the transmission. It does have a leak and I find I'm adding fluid somewhat regularly but it's not too bad. The problems that I'm having is sometimes you can put it into reverse and back out of the driveway and it engages just fine then stop and put it into drive and it hesitates to shift and if you give it some gas, it shifts and goes. It does it in reverse as well and these both happen intermittently. The ongoing issue is if you put it to the floor the car accelerates up to about 70km/h and then hits the rev limiter and won't shift. You let off the gas and it will shift and you can continue on your way. If you slowly roll on the gas, it shifts normally all the way thru and if you're at highway speeds and you put it to the floor, it downshifts and accelerates like it normally would. I did notice one of those hard plastic(and easily breakable) plastic vacuum hoses was broken going into that 'vacuum canister' above the transmission(no cruise in this car either), could that be causing the transmission not to shift under hard acceleration from a stop? Just wondering if anybody has any ideas. Loretta has been a good car to us and I just picked up a 92 3.1 GT for $300 that cranks but doesn't fire that I'm gonna look into this weekend to try and get it running.

Anyways, any help would be greatly appreciated. Really happy to be on here and looking to get some more info so I can make the wife's car a lil more fun for her to drive

[ifixalot]

The trans is getting old. The seals on the clutches harden and don't seal so it takes longer for them to fill. I had this in my 94 mini van.
I got a bottle of trans seal conditioner and after a little while it stopped pausing before going into gear 1st thing in the morning.
The real cure would be rebuild the trans but it's not worth doing on an old car so I tried the bottle cure and it worked.
The other problem you have I'm not sure about but if you do have a vacuum leak it can cause a late shift so fix that.

[3X00-Modified]

Recheck the fluid level and make sure the vac line is making it to the modulator on the front. Most late shifts are from either standard wear and tear, OR the pump is scavenging and running out of fluid in the pan. I have that issue but I'm trying to make it shift at 6500RPM so I need to run 1qt over full.

Also a vac leak should not cause a late shift since there is no vac at WOT... All the modulator does with the vac input is lessens the transmission line pressure when at part throttle to make the shifts smoother, when at WOT it is at full pressure. SO depending on when that line broke you could have been driving it at full pressure for a while which would wear out the pump quickly and explain these issues.

[ifixalot]

and the line pressure is used by the governor to determine shift points.
TPS, TV cable and vacuum modulator all play apart in determining shift points.

[3X00-Modified]

No they don't... The 4t60e shift points are electronically controlled by RPM and MPH. There is no TV cable on that trans.

[UncleFluffy]

ok...thanks for the help...I'll try and get that fixed....currently in the process of replacing a CPS in a 92 3.1 GT....$42 for one of those here in canada at the local parts store......ugh.....gotta track down an oil pressure sensor too that works with the gauge as mine appears to have busted....but i'm not paying $50 for that one too.....looks like I may be off to the wrecker on monday for that