2005 WRX 4EAT Problem shifting from 3rd to 4th under full throttle

[1986Brat]

I have a 2005 Saab 9-2x Aero (WRX) 141,000 miles, completely stock, with the 4EAT automatic.   Under full throttle, at about 70 mph, it will shift from 3rd to neutral (and redline) rather than shift to 4th.  I must let off the throttle and give it a few seconds to find 4th gear when this happens.  Under normal acceleration, it has no problem going from 3rd to 4th gear. 

 

I have just replaced the transmission fluid and filter (using genuine Subaru stuff) and still the problem persists.

 

I have never driven anything with an automatic transmission before and really don't know where to start with this, it is also difficult for me to find anything on the web about this exact problem, so any help would be appreciated.  Thank you!

[GeneralDisorder]

Just get a used trans. They are cheap. It's slipping and that means an overhaul which is not economically viable nor a good idea in my experience as few trans shops know what they are doing inside a Subaru auto.

 

GD

[1 Lucky Texan]

GD - that trans model isn't 'special' or 'rare' is it.

 

any flashing lights at start-up? maybe there's a TCU code stored.

 

any dents in the trans pan?

 

still, at that mileage - you might find a used trans as GD said, maybe with a lot less miles. LKQ or www.car-part.com ?

[1986Brat]

That's not what I wanted to hear... now I have two subarus that need transmissions.  Nothing else I could try?

[1 Lucky Texan]

3 drain and fills are required to get about 85% fresh fluid because of how much is left in the torque converter. Unless you changed your fluid in a manner that got all of it out.

 

some folks have had good results with a bottle of Trans-X for things like delayed engagement - but it won't fix a broken a transmission.

[GeneralDisorder]

Yes it *is* a special transmission. The WRX auto is different than all the others. It has a special tailshaft section with a more advanced transfer system.

 

You throw away fluid if you want on doing drain and fills but that type of behavior is unlikely to be solved by it. You can't put back worn out clutch material without opening it up. There's no adjustments that can be made externally so that means opening it up and if you do that you might as well overhaul it.

 

GD