93 Impreza won't shift into OD!

[kchurch05]

Hi everyone-
I have a 93 Impreza wagon, 1.8L 2WD automatic with about 150K on it.
For the past few months I've been having a problem where it takes close
to 10-20 minutes at highway speed (55-60) before it shifts into
overdrive.

I've noticed the car has some sort of mechanism that keeps it in 3rd
for a bit before shifting into 4th if it's particularly cold and the
engine hasn't warmed up yet, so I usually take the long way to the
interstate to let it warm up a bit. However, the car doesn't still
doesn't want to shift into OD once I've gotten on the highway with the
engine fully warmed up. I've noticed this problem occurring even when
the weather hasn't dropped below freezing, but it seems now that the
temperature is lower it takes even longer to make the shift to OD.

It's driving me nuts, because the car stays at 3000 rpm in 4th and
absolutely refuses to go into OD even if I speed up slowly to try to
get it to shift... or slow down/speed up, rev the engine, etc... so
basically I spent my entire commute in 4th and then 1 minute in OD
right before my exit. Maybe I'm being paranoid, but I feel like it's
also killing my gas mileage.

Any idea what could be causing this? I had my transmission fluid
changed last month, and I'm up to date on my oil changes/etc. The only
recurring problem with the car is a slow leak with the power steering
pump, but I doubt that has anything to do with the delayed shifting.

Thanks!

-Kendall

 

[strchild]

I have a '93 Impreza sedan, 1.8L AWD automatic with about 140K on it...

basically I spent my entire commute in 4th and then 1 minute in OD
right before my exit. Maybe I'm being paranoid, but I feel like it's

On my shifter I only have, 1st, 2nd, 3rd, 4th, and a "Manual" button. I
don't remember the '93 Impreza automatic having more gears.

Once you're up to speed in 4th, what speed are you getting out of your 3k
RPMs?

~Brian

 

[Orienteer]

It's not an overdrive, but a lock-up clutch for the torque converter. It's
programmed not to work until the transmission oil reaches about 20C. Either
the temperature sensor or the clutch itself has failed. Since it has been
gradually taking longer to come into operation, sounds as though it's the
sensor.

 

[kchurch05]

Ohhh! Makes sense now.

Right, when it hasn't warmed up it will not shift into 4th - e.g., I
can downshift to 3rd and the RPMs don't change, but it DOES shift after
a few minutes. Hence I try to take the long way to the highway entrance
to let it warm up.

When I'm in 4th and waiting for the fake OD to kick in, I'm going 60 at
3000 RPM.

I read somewhere that changing the transmission fluid to synthetic
might help. Any thoughts?

Thanks!

 

[Carl 1 Lucky Texan]

Ohhh! Makes sense now.

Right, when it hasn't warmed up it will not shift into 4th - e.g., I
can downshift to 3rd and the RPMs don't change, but it DOES shift after
a few minutes. Hence I try to take the long way to the highway entrance
to let it warm up.

When I'm in 4th and waiting for the fake OD to kick in, I'm going 60 at
3000 RPM.

I read somewhere that changing the transmission fluid to synthetic
might help. Any thoughts?

Thanks!

Depending on previous maintenance, a tranny FLUSH (or, several
drain/fill/drive cycles) and new fluid could be a good idea. Even if the
fluid is not dark/burnt ,cycling some fresh fluid through may clean out
some gummy deposits. Not sure on a '93, but a vacuum leak may also cause
some problems on some transmissions.

Carl