4EAT doesn't always automatically downshift

[sspeed]

We've got a '98 Outback... 4EAT has been great up until recently, now it doesn't always downshift on its own anymore. From a deadstop it seems to go almost right to 4th, we can floor the accelerator and it won't downshift. We can manually do it and it works just fine. Some days normal operation works fine, other days it does not...

I drove around in a circle tightly and checked for torque bind, there is none... Not that it's related, but I figured that's the first sign of trans problems...

I guess next I could unhook the battery in case the ECU has "learned" something that's keeping it from working quite right...

Any other suggestions? What controls downshift on the trans? It's not vacuum, is it just the ECU?

[Wagondude]

Could be something sticking in the valve body. When was the last fluid change?

[98obster]

how many miles? fluid level and color? does the AT light blink on startup? disconnect the battery and step on the brake and leave it for 20 minutes to reset the ECU/TCU and see if it does anything but you may early signs of a tranny failure. just for grins, make sure there's no AT fluid in the front differential i.e., gear oil in the tranny.

[sspeed]

Ordering up the fluids for a tranny and both diff change tomorrow... this car sat apart for 5 years with the previous owner, I put it back together and we've been driving it for about 4 months, it was great until now... fluid has probably never been changed, so that's a good start, it looked pink and smelled ok... 125k miles total, AT light doesn't blink...

It also had one mismatched tire for a long time with the previous owner, which resulted in the steering wheel pulling to the right constantly.. changed all 4 tires and that went away, then this new problem surfaced, which worries me...

[Zipi]

My AT light never blinked either, but I noticed a big change when I had the trany fluid flushed and replaced two weeks ago. Much smoother shifting, not so much shaking while idling anymore either.

[8kGoodENuff]

Yeah... definitely get the fluid changed. When I changed mine, it was like night to day. I kicked myself in the a$$ wondering why I didn't do it earlier.

Andre

[sspeed]

So, the answer is.... like everyone said, fluid change... 2 drain/fills to be exact...

Drained it the first time, fluid looked and smelled ok, put 4.5 qts new in... took it for a test drive, nothing... thought I'd try 4.5 more just in case... took it for a test drive again and it's back to shifting nicely again...

[sspeed]

What do people think of an auto trans filter kit such as this one?

Derale Cooling Products 13090 - Derale Cooling Products Standard Automatic Transmission Filter Kits - Overview - SummitRacing.com

[sspeed]

Crap, I might have spoken too soon... it's back to not downshifting again tonight... fluid is nice and pink, not burnt...

I was going through the service manual, I think it would take me a month to try all the different tests there... I know nothing about automatic transmissions... bummer to pull the engine, fix it myself, pop it back in and now consider taking it somewhere to have the trans looked at..

[sspeed]

This is driving me crazy... I let it sit all night, took it out, for the first 7 blocks I could downshift in D at will, then once the fluid or something heats up it will no longer downshift, it seems to try, but nothing happens. I can do it with gear selector still...

I don't have any codes at all, or rather no Check Engine lights... I've disconnected the battery and tried it to no avail...

I've done 2 drain fills so far, the second seemed to cure it for a day, but it could have been coincidence.. I saw some sites recommending unhooking the line to the trans cooler and then starting the car and letting fluid flow out under pressure to get most of the trans fluid out... I'm scared of it, but I wonder if SeaFoam and that method might work?