I just picked up my winter beater, 1991 TSi FWD Auto. Have a quick question.

Will the auto trans start shifting like crap if there are voltage issues? I.E: Battery not holding a charge.

Basically, after driving it for a while, the tranny won't shift until about 4-4.5K.

I figure it's voltage, as I just had the car CAA'd from a parking lot (dead alternator).

Any thoughts?

Yes, your transaxle will shift like crap if your battery lacks juice. If the problem persists, it could be that you're in limp mode (3rd gear full time). If you have coolant leaks in your system that will also cause your tranny to shift erratically. FWIW, drain your tranny fluid and put in seven quarts of synthetic ATF. It will make your tranny shift much better than the crap that's probably in there now. Welcome to the world of AT DSM's.

Had a similar problem, ending up with a new tranny in my old 95 NA AT. It would start to shift weird. It would shift at higher RPM than normal. One day, it got stuck in 2nd or 3rd, probably a safety feature ( pretty fansy for dsm ).

$960 for a rebuilt with me R/R the trans

I do have a voltage problem, my alternator's dead.

Tranny fluid was changed 3 months ago by previous owner.

Also check the TCU they have the same cap problems as the ECU in these cars...

Nah, it's fixed now. I changed the alternator with a brand new one and it's working great.

Now my TPS is fracked and causing my tranny to mess around a bit.

Ok, so.. update;

Just drove this thing from Belleville to Sudbury. Drove like a charm all the way up. As soon as I got into town and stop-go traffic, the tranny started shifting like crap.

Here's what I know:

The tranny fluid was changed 3 months ago.
The TPS is throwing a code. The CEL will come on for a bit, then shut off, then come on, then shut off. Pulling the code shows TPS (Code 14)

Here's what the tranny is doing:

Having a hard time kicking down when warm.
When I come to a stop, the tranny will downshift rather hard.
I can launch the damned car when I throw it into reverse.
Shifting from 2-3 or 3-4 may require me to punch it up to 3500 before it will shift.
"POWER" and O/D work, but don't make a difference.

So... There are a few things I feel may be causing this. If anyone has any experience with the 1G Auto tranny's, chime in.

A: ISC (duh)
B: TCU
C: Synchro's
D: Kickdown switch

Any thoughts all? Remember All the above symptoms are when the car is warm! Drives like a charm when it's cold. Also, my T-Stat needs to be replaced, so when the car is stopped, it will get to operating temperature, however when I drive it, the temp does go down.

The transmission will begin screwing up after it has been driven around a while.

Thanks.

First of all, fix the TPS.

My second thought is maybe the transmission is overheating.
How does the cooler look? Get it to temp and then feel the lines. If one line isn't a lot cooler than the other, pull the cooler off and clean it out (providing it isn't simply a pinched line).

Hmmm... good point Rob.

The car's in Sudbury, and I'm back in Belleville, so I'll give that a shot next weekend when I move in.

Hey Ryan the shifting doesn't have much to do with the battery voltage, your tranny internally is starting to go bye bye ... especially considering the fluid was changed 3 months ago, the frciction plates are worn in my opionion. The old fluid had some of the friction particles floating around in it but now the new fluid is to slippery. I went through 3 auto trannys in my old 1g before I converted it to a manual. I had a very similar problem and 3 months later tranny wouldn't shift at all.

Also the reason why is works good when its cold is because the fluid is thicker when its cold and thinner when warm, simply put I would say the main reason this is happening now is because of the fluid change.

Hmmm, you bring up interesting points James, however I don't think that's it.

The car is magically driving fine now! However, once I get a good hour or so in, my check engine light starts flashing. The TPS does play a role in your shifting right? Because that's done.

Car drives very well actually, Amazing for 280K on the thing.

Bahh... as long as it gets me through the next 4 months, then I might do a manual swap over the summer or something.

I wanted to change the AT fluid a while ago, and talked to a guy who owns a good tranny shop (rebuilt my old Maxima tranny)...he said if you never changed the fluid...don't do it now, cause the new fluid will do more damage on the inside. The new fluid is more aggressive chemically, and can damage seals & rubber. I guess once the fluid is there for a long time, its pretty well inert.
I left it alone, and its been OK since. It does sometimes downshift rather hard when coming to a stop.
My Power/Economy sw. doesn't seem to do anything either...wonder if its more to do with ECU timing adjustment than with the tranny shift points.

Throw some Lucas tranny treatment in there. I hear there is a religious following around that stuff.

Yeah... Lucas sits on the LEFT hand side of the Father apparently.