Hello All,

 

New to these forums and looking for some 4eat advice. I have a recently acquired a 1991 Subaru Legacy wagon with the automatic transmission (142,000 miles). After a week of local daily driving, I've noticed a couple things regarding the transmission. Most interested in thoughts on #2.

 

1) This week the 16-flashing POWER light deal on the dash happened. Went through the process to determine code...TCU code 22 - Atmospheric sensor. Unfortunately, not a solenoid that can be replaced from what I gather, but actually has to do with the ECU. Checked the OBDI engine codes, no corresponding ECU atmospheric sensor fault (would be code 45). After a full reset of the ECU/TCU (pulling fuse 14 from the driver side kick panel) this has gone away (for now).

 

2) However, despite the TCU POWER indicator not coming on after the reset, I am still experiencing my primary cause for concern. From a stop, upshift from 1-2 has a little "thud" (not too unusual for the 4EAT from what I gather). Then upshift from 2-3 is smooth, BUT, there is an acceleration lag after the shift before the car starts forward again (I have NOT let off the accelerator pedal at all). It doesn't last long, but it's obvious and annoying. It seems to become less pronounced the longer I drive the car.

 

3) Fluid looks brand new, reddish and clear, not burnt or brown looking at all. It is however above the high mark on the HOT side after driving the car and go through all the gears while on a level surface.

 

Any thoughts on these issues, particularly #2? My plan is to drop the transmission pan, replace the filter, add new fluid, as well as replace the inline transmission filter located near the coolant reservoir. Could it be something to do with the brake band and if so, go tighter or looser? Is there cause for concern here?

 

Thanks(!) in advance for your time and thoughts.

 

Matt

some folks like tha additive Trans-X for older trans with shifting problems.

Ok, yea I read about Trans-X in other forum posts on these 4EATs. Thanks, I'll look into that option with the pending fluid change I mentioned. 1 Lucky Texan, do you have any idea if the brake band could need adjustment based on my description of the problem?

 

Thanks!

I have no knowledge of that, sorry

 

I bet someone else with experience will respond.

 

at 142,000 miles, I might consider a compatible lower-miles trans from a wreck before taking the pan off. But, a '91 may not be worth that effort/expense.

 

fresh fluid helps with gummy deposits and may freshen seals and lubricate better. But, it takes 3 drain/fill/drive cycles to get about 855 new fluid, not just one drain/fill.

 

and trans-X seems to help old seals work better.

Transmission problems are often just a mask for engine running problems.

 

The TCU uses input from engine sensors to determine proper shift points for the trans based on a calculated engine load. The MAP sensor/atmospheric pressure sensor on the engine is one of the sensors it needs input from to properly determine the engine load.

 

Usually a MAP sensor problem is just due to a split or broken vacuum hose. Check all of the vacuum hoses on the engine. A vacuum leak would cause sluggish acceleration or hesitation.

 

When was the last time this car had a tune-up? NGK spark plugs and wires, air and fuel filters? Subaru PCV valve?