1G FWD Turbo Auto Transmission Help!

[rslasrgrl]

Hi All,
I'm having an intermittent issue with my 91 Laser RS Turbo FWD's Auto Transmission.

It usually behaves just fine, no noticeable slipping or rough shifting. However, every few hundred miles I will be driving, and it can be at any speed, in town or on highway and it will go into Neutral. The engine will rev, tach goes way up and I lose all power to the wheels.

I then have to coast to the side of the road and the only way to get the car moving is to shift into first gear and then I must shift the car manualy, 1,2,D. Of course I can't get into 4th gear this way and cannot go very fast.
I can shift up and down through 1-3 gears manually this way and it runs fine. I cannot start out in D when it acts this way.

Then, sometimes just an hour or so later after I park the car, it will run fine again and shift normally on it's own for hundreds of miles.
At first I assumed it was the TCU so I pulled it out and opened it looking for the leaking capacitors. Everything on the circuit board looks very clean.
Not a leak or even a bulge in any of the capacitors. So should I assume it could still be a bad TCU and spend the money to have it tested or replaced or
do these symptoms sound like something in the transmission?

This transmission has about 132k miles on it, I got it from a donor car with 122k miles and do not know how it was maintained. Since I have had it I've changed the fluid (with Mitsu ATF) and filter twice just to be sure. This has had no effect on the problem. The fluid is full and looks clean and smells fine.

The other thing it has done since having this transmission installed is that if I try to coast at a lower speed as when approaching a stop,
the car will act as though I keep hitting the gas and letting off of it. Kind of a surge ahead and then slow down repeatedly unless I actually accelerate or stop. The car runs and idles smoothly except during coasting in lower gears during the surging.
Has anyone else had these problems?

Any ideas would be greatly appreciated.
Thanks!
Kristen

 

[DSM1G90]

Possibility that the fluid pump in the tranny is going out.

TCU can look visually clean, but the caps could be all but dried out (or even shorted, or open inside) which then they can't do the filtering the current as needed along with some of the driver chips are bad.

Yet, have to ask a question: I didn't know that 91 FWD turbos got automatic trannies - not until they went 1Gb with AWD in 1992.

Does your VIN have a letter "M" for '1991, or "N" for 1992 in the number string?

 

[rslasrgrl]

My car started out as a 91 Laser RS 2.0 N/T Auto. About 7 years ago I had an engine and transmission swap (along with ECU and TCU) from a 92 Talon TSi FWD.

If it is the fluid pump, is it expensive/difficult to replace and would it explain my ability to shift through the gears manually?

 

[whe3ls]

im pretty sure overdrive is going out. It wouldnt hurt to change the fluid

 

[bryanwheat]

sounds like the end clutches are burn't. It's a relatively easy fix.

 

[DSM1G90]

My wife's friend, who has a '92 Diamante with the F4A33 auto is doing the same. Thus told her to just run it with OD disengaged until the end clutches in her tranny are replaced, then she can use OD again.

Which the tranny doesn't have to come out.

Drain the fluid, raise it up and take off the passenger tire, and you see the end clutch plate cover on the end of the tranny. Matter of popping that cover off, take out the assembly, replace clutches and the reverse to put it all back together.

Please do a search on how to rebuild the end clutch assembly in these forums.

Good luck- DSM

 

[rslasrgrl]

Thanks for the replies. It looks like most think it's the end clutches. Where is the best place to purchase the kit and what brand is best to use?

 

[pats16valve]

IPT has what you need.

 

[bryanwheat]

You want to replace the seals on in the hub also. Bad seals is usually what causes the clutches to go bad because the pack can't hold enough pressure on the clutches and causes them to slip.

 

[rslasrgrl]

It was the end clutches. They were replaced and 4th gear has returned. Thanks for your help to everyone who replied!