07 Legacy Spec.B - Jerky Acceleration

Have you thought about a plug momentarily fouling with too much gass when you floor it?

That's what mine feels like

On Wed, 29 Aug 2007 08:54:38 +1200, Bugalugs uttered like so:

That sounds like as reasonable explanation as any, but what would cause such a thing to happen in a brand-new vehicle?

Anyway, I posted this same question on the forums at

and apparently this is a very commoncomplaint, about something that people have been referring to as"stuttering" or "studdering." It sounds like the problem might becaused by a fault in the ECU program, though I'm not certain yet thatmy problem is exactly the same one they're describing.

I have an 07 Legacy 2.5 GT sedan with automatic, and, I've felt a slight "hesitation" or something, almost like the power shutoff, then back on, while accelerating a few times. It's almost like you ran over a slight bump in the road, and, the car kinda slows then speeds back up quickly.

I know it's a different engine, but, maybe it's something to do with the

4-cylinder or turbo?

Lothar of the Hill People wrote in news: snipped-for-privacy@4ax.com:

This is a known issue with the 07 STi, and I just read that it MAY extend to the 07 Legacy Spec.B also. It has to do with the ECU mapping, which apparently Subaru had to radically modify to meet the new emissions standards for 2007. Subaru released an ECU reflash for the STi, but it does not really fix the problem.

You might want to check out the online forums.

Dee

On Wed, 29 Aug 2007 15:31:26 +0000, Dee uttered like so:

I had actually already checked out the forums at

(which I guess is a different website thanthe URL you posted above) yesterday, after I posted my question here,and one of the replies I got said basically the same thing you justsaid. He elaborated that the problem is shared between the 2007Legacy Spec.B and the STi because they share the same "new" ECU. Can you elaborate what you mean when you say the ECU reflash doesn't really fix the problem? I read a few people post that they had a reflash done and it did fix the problem (though only temporarily for some people).

On Wed, 29 Aug 2007 06:21:27 -0600, "Bill Bradley" uttered like so:

That sounds somewhat similar to what I'm experiencing, but I'd describe it more like a very quick stutter every time I try to accelerate hard. On my car though, I don't think it's a transmission issue. I have a 6-speed manual. Like the other poster said, it appears to be a poorly-programmed ECU. My dealer told me today that there is an ECU update available for this issue, so I'll try that out and see if it fixes it.

Lothar of the Hill People wrote in news: snipped-for-privacy@4ax.com:

I wrote that it doesn't really fix the problem because from reading the forums it seems that for the majority of the people the symptoms return. I'm not sure why that happens; perhaps it has something to do with the ECU "relearning" or reverting. There are a couple of people who say they've never experienced the hesitation/stuttering, but they are in the minority.

For me, the reflash smoothed things out for a couple of days, and then it reverted back.

A couple of things that work for me: keep the revs up and in the boost zone so that when you need the turbo it will respond immediately. Also, turn the A/C on - people are finding that this somehow reduces or eliminates the hesitation. This summer I have had the A/C on constantly and the car does seem to run better and smoother.

There is a poster on IWSTI who swears up and down he has never experienced the hesitation, but he lives in Miami, so you can imagine he's probably never driven the car without the A/C.

Dee