Input needed for N/A AT Forester

lebshiff21 · **Joined:** Thu Aug 31, 2006 11:26 am **Posts:** 7

I found this thread on nasioc:

http://forums.nasioc.com/forums/showthr ... ?t=1537010

It directly relates to an "issue" that's been bugging the crap out of me: I'm going 65mph on the highway using cruise control, I want to speed up to, say, 68mph, so I use the cruise control arm to "accel"... Immediately the car downshifts and seemingly floors it. SUPER ANNOYING.

What I'd like to know, and can't seem to find any info on, is if this modification to the tables described in the thread is safe for an AT? Do these tables have anything to do with the module that controls the trans?

lebshiff21 · **Joined:** Thu Aug 31, 2006 11:26 am **Posts:** 7

bump - anyone have any input?

Jon [in CT] · **Posted:** Wed Nov 05, 2008 6:52 pm

That NASIOC thread has nothing to do with the problem you described. Need details about your car (like year and market).

williaty · **Joined:** Tue Jul 24, 2007 6:28 pm **Posts:** 214

yeah, I wrote that thread on NASIOC and I can't even figure out a way to pat myself on the back enough to make that thread relate to this :lol:

The bigger issue sounds like your TCU logic is set to downshift too readily under those conditions. I don't think there's anything you can do about that.

lebshiff21 · **Joined:** Thu Aug 31, 2006 11:26 am **Posts:** 7

williaty wrote:

yeah, I wrote that thread on NASIOC and I can't even figure out a way to pat myself on the back enough to make that thread relate to this :lol:

The bigger issue sounds like your TCU logic is set to downshift too readily under those conditions. I don't think there's anything you can do about that.

This is what you wrote on NASIOC:

Quote:

The 06 saw an additional, surprising, benefit. The 06's cruise control had always been a little flaky. Frequently, when you would set it, it would floor the car, gain about 8-10MPH and then settle back down to the target value. It also had trouble dealing with any change in the angle of the ground (hills) at all. Altering the DBW tables (and I strongly suspect it's specifically related to simplifying the Target Throttle Plate Angle tables) has completely eliminated the problem with hills and reduced the surge on set to 1-2MPH. A win all around!

Isn't that related?

It's a MY05 USDM Forester X

williaty · **Joined:** Tue Jul 24, 2007 6:28 pm **Posts:** 214

No, you're talking about the tranny downshifting too easily. I'm talking about the car picking up speed when the cruise is engaged.

lebshiff21 · **Joined:** Thu Aug 31, 2006 11:26 am **Posts:** 7

I thought the flooring of the accelerator with the touch of the accel button was what you were referring to. Isn't the tranny downshifting related to the way the accelerator responds to the accel button (target throttle plate opening angle)?

williaty · **Joined:** Tue Jul 24, 2007 6:28 pm **Posts:** 214

The cruise seems to open the throttle a fixed amount when it's set of when you hold the cruise lever up to accelerate. I've not yet seen a table where you can alter this. Your problem seems to be that this increase in throttle position is larger than the amount required to kick the tranny down at cruising RPM. That sucks. I've actually driven an old hydraulically-actuated auto that did that. It went to the dealer and they changed some sort of valve to make it require more torque at low RPM before it would downshift.

lebshiff21 · **Joined:** Thu Aug 31, 2006 11:26 am **Posts:** 7

williaty wrote:

The cruise seems to open the throttle a fixed amount when it's set of when you hold the cruise lever up to accelerate. I've not yet seen a table where you can alter this. Your problem seems to be that this increase in throttle position is larger than the amount required to kick the tranny down at cruising RPM. That sucks. I've actually driven an old hydraulically-actuated auto that did that. It went to the dealer and they changed some sort of valve to make it require more torque at low RPM before it would downshift.

Interesting... thanks, maybe I'll ask the dealer if there's anything they can do. Thanks for the research and info.

Jon [in CT] · **Posted:** Thu Nov 13, 2008 5:26 pm

There is a reflash available from Subaru for the TCM in your 05 non-turbo Forester. The problem fixed is described as: "Downshift shock 4 to 3 and 3 to 2 when engine is cold. Applicable when ATF temperature is 20 degree C (68 degree F) or below." Probably not your problem but just thought you should know.

RomRaider

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