2001 Forester w/ AT - 60K miles

 

Got a bad tank of gas and the car drove like crap (surging, stalling, backfiring, missing, pinging) until i could run the gas through - much better, but not great like it was before the bad gas so i changed the fuel filter AND reset the ECU.

 

All bad gas symptoms gone, except now I have this new issue - a slight but annoying "bucking" problem that occurs if going downhill at 35 mph, coasting - just like you would get in an MT vehicle if you let the clutch out at too low an RPM - I'm guessing the torque converter is locking-up incorrectly.

 

I am convinced it was the ECU reset that is causing this bucking. I could do another reset, except I am now getting the best mileage EVER since I purchased this car new 6 years ago. Getting 24-26 mpg every tankful, versus 20-23 previously.

 

I think I'll live with the bucking for a awhile - the 3-4 mpg increase is worth over $200 per year!

 

Any other thoughts ? Thanks!

You realize that a Subaru AT will often automatically downshift when going a steep hill? The car is employing "engine braking" on its' own. Some people find it annoying. The ECU reset may have made this feature more noticable. Then again, it could be something else.

I just bought a 2003 obw A/T, and I find the engine braking very annoying. It makes it feel like something is wrong with the transmission. On down hill grades, it shifts into gear with a noticeable, but mild bucking.

 

I initially thought there was a problem, but the service manual describes the engine braking feature.

 

Matt

Thanks for the replies. Not sure if the AT isa ctually downshifting or if tits the torque converter locking up, the rpms do not raise up like they would on a downshift.

 

The other thing I am noticing since this started is a slight performance (acceleration) decrease.

 

I can live with all this as long as I keep getting the improved mileage!

 

Thanks again.

My new 2006 Outback Sport with MT feels like this all the time and I really hate it. It just annoys the heck out of me.

 

How do you reset the ECU? I'd try anything to get rid of the bucking and surging and braking. Thanks.