I just got my '93 Legacy Touring wagon back from the transmission shop and noticed an odd change. Here's the rundown of the work done:
• Rebuilt torque converter with approx. 400-500rpm higher stall speed
• Rebuilt 4EAT with slightly modified valve body for firmer shifts throughout
• Transmission cooler
What happens is that when I have the selector in "3" and let off the gas the RPMs completely drop to engine idle speed; not immediately but just as if you put the selector in Neutral. There's no compression braking at all. It doesn't matter what speed I'm at and it only happens in "3" whether or not I have the "Manual" button depressed or not. As the car decelerates I can feel the transmission trying to engage downshifts but they don't engage; just an initial bump from the downshift action and then the car keeps coasting. Manually downshifting into "3" from "D" doesn't make a difference but downshifting into either "1" or "2" plants it FIRMLY into the appropriate gear (very nice for spirited driving)
Could it be that the ECU is getting confused by the slightly higher stall speed? I doubt the valve body adjustments could be causing this; it appears to be an electronics misunderstanding to me but I know very little about how the 4EAT and ECU talk to each other. Any enlightenment will be greatly appreciated since I really do like the way the 4EAT behaves now other than that glitch! I have confidence in the shop I took it too since they have been around for over 4 decades and regularly work on the 4EAT; but I guess they're not familiar with the issue since not many people want performance rebuilds on their 10+ year old Subaru wagon...
I don't have the answer to your question, but I doubt it has to do with the stall speed and electronics not getting along. Based on my very simplistic understanding of automatic transmissions, I'd think it was either a problem with the valve body as THAWA says or a problem with the torque converter staying unlocked.
The transmission control unit (TCU) is separate from the engine control unit (ECU)... just in case you're trying to do searches or something and having trouble.
"Just reading vrg3's convoluted, information-packed posts made me feel better all over again." -- subyluvr2212
I checked all the connections and they seem fine. I'm going to ask about the TC lock-up and valve body. I might have them revert the valve body to stock settings to see if that's the cause. But that's a last resort since i REALLY like the shift quality right now! I've been paying very close attn. and i've noticed that overdrive while in "D" seems to dip in and out too easily; it's very sensitive to throttle position now. I'm going to try to see if there's any codes on the TCU.
I bet it's gotta do with your TC upped stall speed. With a stall of, say, 2000, you have to stay above 2000 RPM on the highway and in the city (for cruising purposes).
Your TC is probably falling below the stall speed as it locks when you let off the gas.
Just an update: I finally got the problem sorted out. Apparently the valve body adjustments the trans shop made, in addition to the shift kit, were a little too much and caused the engine braking to disappear for some reason. So they got another stock valve body and just used the shift kit and it works perfectly now.
I actually am happiest with this setup. It's not super-firm like when i first got it back (with the engine braking problem) but definitely quicker shifting while still being unobtrusive on the daily commute routine. Plus, they didn't charge me for the shift kit.
what is this shift kit you speak of? I know nothing of these, but since i'm now going to a 4EAT, i'd kinda like to know.. What kind of tranny cooler did you use?
THAWA: yup, you called it 1st! I still wish they could have figured out exactly what the problem with the valve body mod was though. For whatever reason it didn't want to play with the shift kit.
Tristan: I don't know exaclty which shift kit the tranny shop used, but it was probably something like the TransGo kit which is basically a rebuild kit with upgraded/reinforced components to last longer and give a slightly quicker shift (quicker/firm shifts, in general = lower trans. temps which = longer life). This kit is not a valve body mod.
FYI, all the transmission work was done at Leon’s Transmission in Garden Grove, CA
