4.444 swap into 91 SS, trans issues

[86 Wonder Wedge]

O.k, this is a cross post from LegacyCentral, but I think I'm into electronics/logic stuff at this point.

 

Info: MY91 (07/90) Legacy Sport. Swapped in a MY97 Outback 4EAT (4.444) and matching 4.444 LSD. Plug and play, but have intermittent duty C code and on/off-style TB. It's either there, hardcore or non-existent. I'm getting a dragging sensation 95% of the mild-hard, straight line accel situations and a slight vibration at 50+ to match. After parking and shutdown, the car will lurch forward like someone hits me ONLY when the duty C code and TB show-up. No change when FWD fuse is applied (light comes on). Duty C resistance is coming out at 11 ohms (within spec). I'm leaning toward TCU or intermittent duty C.

 

From my post on the BBS:

 

"I think I've found why I'm "dragging" in 1st gear. If I take off slowly, near crawl, the trans and car seem to move forward VERY easily. However, once I get above ~10 mph, it's like traction control kicks in. Engine power is halved and I'm not thrown backward into the seat when I punch it. This is then DIRECTLY related to the TB if I try to turn sharply (even with or without the intermittent duty C code and occasional non-TB).

 

In short, I think AWD is kicking in on mid-hard accel from a standstill and is causing the "occurs most of the time" dragging.

 

However, I want to blame a dying duty C or TCU, but I can't help but think that the new gear ratio is causing the TCU to see a speed difference between VSS1 and VSS2 (even though there is no wheel speed difference) and is locking the duty C to compensate.

 

I need an early TCU expert to chime in and see if that's how it works. If the TCU "backwards" calculates front shaft speed from the speedo head speed (where VSS2 is) and compares is directly to rear shaft speed (VSS1) instead of doing rev/sec to rev/sec."

 

Might the TCU be seeing a false "higher" road speed due the gearing for the speedo not being the same as the 3.9? Or does it not work like that?

 

Ideas?

[Fairtax4me]

If you're having an intermittent problem, it's possibly due to a chafed or cut wire to the duty C solenoid. If the trans was ever set down on the pan, there could be damage to wiring inside the pan.

 

I don't know wha values the TCU uses to determine when to lock the transfer clutch. I do know that it based on TPS input or a speed difference between VSS 1&2, but I don't think the computer is smart enough to know that the FDR is different.

[86 Wonder Wedge]

I need to get my USB to SSM cable in working order to see duty C duty cycle values and my pressure gauge for the transfer pressure.. However, I've heard there is a translator that burns out in the TCU causing code 24/duty C issues... Anyone have info on that?

[86 Wonder Wedge]

Pulled the TCU and it looks pristine (no burned or blown transistors/resistors/IC), but I know that might not mean much.. Had about 50/50 luck with the TB and code 24. Measuring 13 ohm when both the TB is and is not present. I'm still on the hunt for a good gauge to see transfer pressure..