presslab

That page is from the PDFtown link posted in the other thread, should be for 93-96 Impreza. My '90 Legacy TCU will not shift to 4th or lock the TC when the tranny temp is below 64 deg F.

Looks like it's supposed to be 4.7V fully closed, not at WOT; are you measuring it like the FSM says? Looks like when using a voltmeter to take out the ECM, not sure if that means unplug ECM as well. However you have a SSM so why not use that? [ATTACH]6027[/ATTACH] Is it dropping out of 4th or is it just the torque converter unlocking? If the tranny temp is cold it will not shift to 4th. Maybe the temp sensor/connection is flakey. Check the SSM for the tranny temp when it shifts out of 4th.

Hmm, yes you are right. I'm sure it's possible to modify the /4 to /6 in a Legacy TCU. OTOH I don't see any reason why a SVX TCU would not work. There are some SVX ROMs on the www.alcyone.org.uk site, so you wouldn't necessarily need to download your TCU ROM through the select monitor. It would be worthwile to investigate the XT6 4EAT vs a SVX 4EAT to see if the number of clutch discs is similar, etc. Differences could be worked out by modifying the maps but it adds more work, of course.

I use the select monitor software from alcyone.org.uk with my 4EAT, I modified the software with my memory addresses, of course. The one MPH difference is nothing really, the Subaru end wrench article actually says be wary if they are always the same because that means one of the VSS is not working right. Mine is usually pretty close but sometimes it is +/- 1 MPH when going straight and while turning it can be a few MPH off. Yes remove the TPS and squirt the contact cleaner into a crack while turning it. Don't use any other solvent like brake cleaner it will damage it. I'm not sure how much it matters but I'd think the lube is a good thing too - it's probably some light silicone oil. You should readjust it, but I'm sure if you mark it's location before you remove it you'll be ok. You ever hear a radio that is scratchy when you turn the volume knob? The TPS is the same thing as that volume knob, a potentiometer.

One MPH error at what speed? Probably no big deal. The front VSS speed is driven off the diff speedo gears. The rear VSS is off the "teeth" on the transfer clutch hub. Changing just the sensor should have no effect as long as both are working correctly. Is the TPS in it the one from the junk yard? Maybe it is dirty, you can clean it with some contact cleaner. Radio Shack has some with a little lube in it; that's what I used when my TPS was dirty. Just spray it in there and turn it back and forth a bit. http://www.radioshack.com/product/index.jsp?productId=2103700 So how do you know the TPS voltage is spiking? Is this just inferred from the TCU downshifting erratically? Have you put a scope on it to see the TPS signal?

So are you saying that when it should be shifting into 3rd the engine just spins freely? Have you tried unplugging the TCU? This will cause the tranny to use 3rd gear with full line pressure, and a locked transfer clutch. If unplugging the TCU doesn't work then it's something hydraulic/mechanical inside the tranny. Freewheeling in 3rd gear sounds like the high clutch is not working right. Sorry to hear you are laid off, I just got another (albiet low pay) job after being out of work for 6 months.

If it has problems in the "L" selector position I would expect something wrong in the extension case and not the VSS sensors. In the "L" position the Duty C acts the same as if the front wheels slip. My guess is that your transfer clutch has too much slop and needs a thicker drive plate, or your extension case has worn down and is leaking a lot of transfer clutch pressure. Subaru came out with newer lathe cut rings that are softer but if your extension case is worn it's too late. Your transfer clutch hub could have deep grooves as well. Mine had moderate grooves and I left them alone and it works fine. While you are in there replace the orifice plate behind the solenoid as there have been a couple revisions. When you moved the "new" clutch discs to your current transfer clutch hub, was the stack play from 0.2-0.6mm?

I love my soob in the cold, hot air out of the vents in 2 mins! It's cold for here (N. Cal) but only about mid 20s F at night. A while ago I noticed that the heater duct on the pass side (by the center console, under the dash) was leaking a lot of cold air. I tightened up the metal strap with some wire and it's been great since.

I was an EE for a company that made automated measuring machines. It was a crappy place, I'm much happier now that I'm not there any more. Canada has less people, beautiful scenery, and lots of outdoor stuff to do; perfect for me. I'm done with the "rat race," it's not worth it. I'm checking out Vancouver Island, and I've been up there twice. Lately I've been looking for jobs and there aren't many. Maybe I'll go back to school. My DCCD control is this switch; a few dollars from the surplus store: I still need to make a decal with the switch settings. Maybe an Avery label printed on color inkjet would look good. A quick spray of matte clear coat to finish it off.

I'm sure it's possible, but I believe it uses a different CPU; I haven't cracked the cover open on my ECU. It's a lot different, like Macintosh vs Windows. (Although those use the same CPU now.)

Thanks Gary, this is my first time modding any ROM on a car but I'm pretty good at this kind of stuff. I used to do the hardware/software for motion control, servo loops, that kind of stuff. About 6 months back I quit my job because I was about to have knee surgery and I hated who I worked for; that gave me some time to tinker with stuff. I have a job again but just doing computer repair, it pays the bills for now. I'm thinking of moving to Canada soon but this isn't the best time of year. My citizenship has been approved and I should get my certificate any day now.

Yes, it's possible to modify the shift points, torque converter lockup, line pressure, transfer clutch, etc. Phil over at www.alcyone.org.uk has been doing some work with SVX TCUs, which are similar to the Legacy ones. I used his tcuscan software to interface to the select monitor port on the Legacy TCU. The tcuscan software had all the wrong memory locations though, so I had to figure this out; while the Legacy and the SVX TCUs use the same type microprocessor, the circuit board and the ROM are similar but not the same. To hack it I downloaded the ROM through the select monitor interface. I then used IDA Pro software to disassemble the ROM to the assembly source code. This is the lengthy part, where I had to figure out what the code meant and what it was doing. Once I figured out where to hook into the code, I made my paddle and dccd assembly code and compiled it. I then used a hex editor to modify the ROM file so that it would execute my code before it executed the original code. I stuck my code in some unused ROM locations. Then, the ROM file was burned into a chip and stuck on the TCU. Okay, it wasn't that simple, more like crash and burn. But after a while I got it to work and with some more trial and error the paddle and dccd was working just the way I wanted.

Thanks. If you get serious about this, I could email you my ROM file, although you'd need an EEPROM burner. You'd need up upgrade your transfer clutch if it's the same as mine was. Yes, it's currently set up to enable/disable paddle mode by pulling both paddles at once. Once out of paddle mode it works automatic just like before.

It seems the forum does not allow text file attachements anymore, so here is the code in this post. Unfortunately the formatting is messed up so it's hard to read. ; Paddle shift TCU mod for '90 Legacy AWD TCU 31711AA911, v705005 ; Ryan Press ; version 1.1prevPaddleFlags EQU $D0paddleFlags EQU $D1paddleGear EQU $D2ignorePaddleCtr EQU $D3signedSlipRPM EQU $D4tempVar EQU $D6paddleFlagOn EQU $1paddleFlagUp EQU $2paddleFlagDown EQU $4paddleFlagStopped EQU $8vehicleSpeed EQU $14inShaftRPM EQU $19engineRPM EQU $32currentGear EQU $45shiftFlags1 EQU $4FgearParm EQU $BCpowerMode EQU $51paddleUpPort EQU $08paddleDownPort EQU $07paddleUpBit EQU $40paddleDownBit EQU $40redlineTable EQU $CDFFLookupShift EQU $D99CCalcVSS1 EQU $D6EDCalcSol3 EQU $DF46CalcPowerMode EQU $DA84IGNORECT EQU 8 ; Number of cycles to ignore input from paddlesSTOPPEDKPH EQU 3 ; Vehicle speed <= STOPPEDKPH then we are stopped org $F000 ldaa gearParm staa paddleGear ldaa paddleFlags anda #(~(paddleFlagUp | paddleFlagDown) & $FF) ; Clear paddle flags staa paddleFlags ldaa paddleUpPort bita #paddleUpBit bne GetDownPaddle bset paddleFlags, paddleFlagUpGetDownPaddle ldaa paddleDownPort bita #paddleDownBit bne CheckOnOff bset paddleFlags, paddleFlagDownCheckOnOff brclr prevPaddleFlags, paddleFlagUp, CheckOnOff1 ; Check if both paddles pressed, but not previously brclr prevPaddleFlags, paddleFlagDown, CheckOnOff1 bra CheckPaddlesCheckOnOff1 brclr paddleFlags, paddleFlagUp, CheckPaddles brclr paddleFlags, paddleFlagDown, CheckPaddles ldaa #IGNORECT ; Reset paddle ignore staa ignorePaddleCtr brset paddleFlags, paddleFlagOn, CheckOnOff2 bset paddleFlags, paddleFlagOn ; Paddle mode off, so turn it on jmp ExitCheckOnOff2 bclr paddleFlags, paddleFlagOn ; Paddle mode on, so turn it off jmp Exit CheckPaddles tst ignorePaddleCtr beq CheckPaddles1 dec ignorePaddleCtr jmp ExitCheckPaddles1 brset paddleFlags, paddleFlagOn, CheckRedline ; Exit if not paddle shift mode jmp ExitCheckRedline ldx #redlineTable ; Get redline rpm from table ldb paddleGear abx ldd engineRPM lsld lsld tab ldaa 0,x sba ; compare engineRPM to redline bcc NotRedline inc paddleGear ; Redlined, shift up ldaa #IGNORECT ; Reset paddle ignore staa ignorePaddleCtr bra ExitNotRedline ldaa vehicleSpeed cmpa STOPPEDKPH ; If we just stopped, set gear to 0 bhi NotStopped brset paddleFlags, paddleFlagStopped, CheckUpPaddle bset paddleFlags, paddleFlagStopped clra staa paddleGear bra ExitNotStopped bclr paddleFlags, paddleFlagStoppedCheckUpPaddle brset prevPaddleFlags, paddleFlagUp, CheckDownPaddle ; Check if up paddle pressed, but not previously brclr paddleFlags, paddleFlagUp, CheckDownPaddle ldaa #IGNORECT ; Reset paddle ignore staa ignorePaddleCtr ldaa paddleGear ; Increment gear but only if gear < 3 cmpa #3 bhs Exit inc paddleGear bra ExitCheckDownPaddle brset prevPaddleFlags, paddleFlagDown, Exit ; Check if down paddle pressed, but not previously brclr paddleFlags, paddleFlagDown, Exit ldaa #IGNORECT ; Reset paddle ignore staa ignorePaddleCtr tst paddleGear ; Decrement gear but only if gear not zero beq Exit dec paddleGear ; Downshift overrev protection ; Check for over-rev, multiply RPM by ratio difference ; newRatio / curRatio * inShaftRPM + (engineRPM - inShaftRPM) ; use CalcVSS1 instead which calculates inShaftRPM with VSS and currentGear ldd engineRPM ; Calculate TC slip subd inShaftRPM std signedSlipRPM ldaa currentGear ; Save currentGear staa tempVar ldaa paddleGear staa currentGear jsr CalcVSS1 ; Use CalcVSS1 function to get inShaftRPM ldaa tempVar staa currentGear ; Restore currentGear ldd inShaftRPM addd signedSlipRPM lsld lsld sta tempVar jsr CalcVSS1 ; Put VSS1 variables back to normal ldx #redlineTable ; Get redline rpm from table ldab paddleGear abx ldaa 0,x ldab tempVar sba bcc Exit inc paddleGear ; Would be over redline, so put it backExit ldaa paddleFlags staa prevPaddleFlags ldaa paddleGear staa gearParm brset paddleFlags, paddleFlagOn, Return ; Exit if not paddle shift mode jmp LookupShift ; Execute automatic shift lookupReturn rts org $F600 brset paddleFlags, paddleFlagOn, SetSS3 ; If in paddle shift mode, set solenoid 3 jmp CalcSol3 ; Execute automatic shift solenoid 3 calcSetSS3 bclr shiftFlags1, $10 ; Set shift solenoid 3 off for engine braking rts org $F650 brset paddleFlags, paddleFlagOn, SetPwr ; If in paddle shift mode, set power mode jmp CalcPowerModeSetPwr ldaa #1 staa powerMode rts ; Driver controlled center diff mod for '90 Legacy AWD TCU 31711AA911 v705005 ; Ryan Press ; version 1.0dccdInput EQU $11 ; Previously used as atmospheric pressure inputCalcSolCDuty EQU $E062CalcSolCReturn EQU $E23CsolCtargetDuty EQU $72solPeriod EQU $C005 org $F800 jsr CalcSolCDuty ldx #dccdMap ldaa dccdInputmapLoop: cmpa 0,x bls mapLoopEnd inx inx bra mapLoopmapLoopEnd: ldd solPeriod ; $4E20 = 100% subd solCtargetDuty ; solC = period - ((period - solCduty) * dccdMap / 64) ldab 1,x cmpb #$FF ; if dccdMap is $FF then just lock it up beq fourwd mul lsld bcs fourwd lsld bcs fourwd jmp CalcSolCReturn fourwd: ldd solPeriod ; Set duty to max (4WD) jmp CalcSolCReturn dccdMap: fcb $B, $0 ; FWD fcb $21, $30 ; 75% fcb $37, $40 ; 100% (no change) fcb $4D, $60 ; 150% fcb $61, $80 ; 200% fcb $75, $FF ; 4WD fcb $FF, $40 ; DCCD input disconnected (no change)

This is about my paddle shifter project on my GL-10 with the 4EAT automatic. I used a 1990 Legacy TCU because it was easier to modify the code, it uses a much faster 68HC11 processor vs the stock GL-10 TCU which is an old Hitachi type. The first thing was to graft the Legacy TCU onto the GL-10 harness. It's quite straightforward - I basically matched up the wires using the wiring diagrams. There are a few differences, like the "1 hold" switch, but these things aren't needed once the paddle shift is in place. The Legacy also uses a atmospheric sensor input which I left disconnected. The tach input to the Legacy TCU is 0-5V where as the GL-10 TCU is right off the coil. I initially hooked it straight up and it worked, however I wasn't really happy with it so I used a zener diode and a resistor to clip the signal. Apparantly the Legacy 4EAT has a stronger high clutch, as initially the 2-3 shift was pretty slow. The transfer clutch has changed as well. To resolve the 2-3 shift problem, I modified the maps in the TCU ROM to make the 2-3 shift faster. This solved that problem. Initially I modified the maps for the transfer clutch; this made the AWD work again, but it wasn't so great. Sure, it worked as well as it did with the GL-10 TCU but there was a lot of room for improvement. There was a delay in engagement, and it sometimes spun the front tires on takeoff. I decided to upgrade the Duty C solenoid/valve body in my 4EAT to a Legacy unit, along with the orifice plate right behind the Duty C valve body. There were obvious differences in these parts, it seems like it is designed to flow much more fluid volume to the transfer clutch unit. I also replaced the friction discs while I was in there. It's a tad grabby now, but it works much better; I'm back to using the original Legacy TCU transfer clutch maps in place. I'm sure the clutch plates just need to break in a bit, as the cluch was pretty tight when I put it back together. The TCU was modified by soldering a socket onto the circuit board. I was going to use a different Legacy TCU but it had no holes to solder the socket! I'm not sure what year that TCU was. After the socket is in place, there is a 0-ohm resistor on the bottom of the board that needs to be moved to enable the new socket. The ROM chip I am using is a SST27SF512; this EEPROM is easily reprogrammed without a UV eraser. The paddles are just bent metal rods that I tack welded to some switches. They work pretty good. I made a small metal frame that attached to the steering column; the switches screw down into that. The paddles use the "manual" and "power" button inputs to the TCU. The paddle code will protect against overrev on downshift, upshift at redline, and downshift to 1st when stopped. My most recent modification is a DCCD knob. It's a six position rotary switch with FWD, 75%, 100%, 150%, 200%, 4WD settings. It still allows the TCU to calculate the transfer clutch value but it then it modifies it depending on the knob setting; 100% would be stock, 200% would be twice as aggressive as stock, etc. The DCCD knob switch has some 1N4001 diodes wired in series between each pole. The FWD switch pole is attached to ground and the common is attached to the atmospheric sensor input. FWD=0V, 75%=0.5V, 100%=1V, 150%=1.5V, 200%=2V, 4WD=2.5V. If the switch is disconnected the code defaults to 100%.

That looks like a pretty good quality kit. I am looking forward to your pictures. I do wonder though, if a bulb burns out is it a standard type replacement?

I've holed the side covers on my dirt bikes and they have been welded no problem, no leaks; it might be worth a shot. You can do it! The newer (I think Legacy '93+) extension housings have a steel sleeve installed where the two "lathe cut rings" ride. You can see the two rings on the transfer clutch assy near the start of the splines. The rings will wear a groove in the aluminum and pressure will leak out making the AWD not as effective. Supposedly the newest rings available at the dealer are also softer.

Looks like a pretty clean break, maybe you can weld it up yourself? A real weld, not J.B. Weld like the pic of Turbone. When changing the extension housing you should check the transfer clutch end play. Subaru sells different thickness thrust bearings for this. My tranny mounts tore the same way. I happened to have some urethane windshield adhesive left over and I glued them back together. It's only been a few months but they are still looking good.

The VLSD uses a non-newtonian fluid, sealed inside the diff. This fluid changes its viscosity based on the shear stress. The two sides of the diff have plates with little burrs on them; when the difference between the two sides is great enough, the shearing action of the burrs in the fluid causes the viscosity to change and become thick, effectively locking the plates together. I would guess that a tire would slip one revolution or so before the VLSD locked. The clutch type LSD on the other hand uses the propeller shaft torque to change the pressure on the clutch pack. So under heavy throttle the clutch binds up. In my opinion the clutch LSD is better for street, VLSD better for mild off-road and some kind of locker is best for rock crawling.

Just wanted to bump this thread. I've decided to use a Legacy TCU. It's currently wired in and working okay; the AWD is having a few problems. It basically disables AWD at about 15 MPH. I believe it is due to the R&P/tire size difference in the Legacy. The front/rear speeds aren't quite matched up, about 6% error. I have downloaded the Legacy TCU ROM through the Select Monitor interface. I've been disassembling the ROM and I've identified the const for the vss1, and I believe I can correct the 6% error which I hope will fix the AWD problems. The Legacy TCU should have better control of the AWD than the GL10 TCU, it already works better at a standstill. It has a Motorola 68HC11 which is a much easier to deal with CPU than the GL10 which is some Hitachi CPU. The eventual plan is to add my own paddle shift code to the ROM, there is a lot of unused space in there. There should be a couple inputs available for the paddle shifters.

My stop warning lamp was on, it turned out to be the coil bulb sensor thing at the rear. It only came on when I pressed the pedal so I think your problem is different.

My EA82T with 137k miles is 124, 125, 126, 122.

Well, if you are at stock boost it's probably not running lean... Hook a multimeter up to the o2 sensor wire and ground. Have someone in the car watch the meter while you do a full throttle run. If the voltage drops to like 0.1V then it is running lean. It should stay around 0.8V or so when full throttle. You can see how the top of the FPR is dimpled in. It's a very delicate operation, be careful or you will ruin the FPR. If you don't also modify your MAF, your car could run like poo and get bad mileage. You do not need a specific fuel pressure gauge, any pressure gauge that goes to 70 PSI or so should work fine.

Yeah the first test would have been better with straight gasoline. However it sounds like all the tests were at 40 PSI, so the RRFPR doesn't matter. 100% duty cycle just means the injector is full on, maximum flow. There are two readings because it was tested at two different fuel pressures. The output flow rate is almost directly proportional to the fuel pressure.

A lot of people say the stock injectors are 180cc, but at what pressure? The 280ZXT are ~250cc @ 40psi. Someone on here measured the stock turbo injectors at ~220cc @ 40psi. http://www.ultimatesubaru.org/forum/showpost.php?p=323920&postcount=68 http://www.ultimatesubaru.org/forum/showpost.php?p=598691&postcount=3