Help needed with 09 Legacy base model (H4, 4AT)

[wsn]

New to the forum. I tried to search old posts, but could find anything that's relevant (maybe I didn't use the right keywords).

 

Here it goes:

 

I bought my car in May 2009 and everything was fine until now. When I drive the car at roughly 35mph, occasionally the car would suddenly launch forward. It's rare, but keeps coming back maybe once every 20 miles.

 

It's not like the Toyota unintended acceleration thing. My Legacy isn't keep accelerating. Just a single notable push. It can happen during light acceleration or even cruising. It doesn't happen at other speeds or during heavy acceleration.

 

I am no expert but I guess it has something to do with improper shift timing of the 4 speed automatic.

 

Does anyone know what it is? I thought by 2009 whatever problems should have been resolved. Thank you very much!

[surolegga]

If you want to rule out shift timing, stay in the gear you are in @ 35 during light acceleration (3rd I would guess) with the sport shift.

 

It sounds more like a computer problem to me. I have a '08 Limited (also auto) and the only wierdness I've ever had around 35mph is a strange harmonic tone.

 

Maybe the dealer can reflash you for free, is the car a PZEV?

[katalyst]

i'm not sure i've come across another member that has described a similar issue. but i do know that the 08+ PZEVs did suffer from erratic idle which was solved by a reflash of the ECU

 

but that seems liek a different problem since you're already rolling. your car should be under warranty still? try to replicate the problem with a tech in the car at the dealership.

[wsn]

Thank you both for the advices! My car is indeed a PZEV.

 

How is erratic idle defined? When just started, my car would rev at about 1000+ rpm in P gear. When I put it in D or R and hit brake, it's about 700 rpm.