How to Tune 5EAT Line Pressure

[ClimberDHexMods]

I had no TP issue when adjusting RT on my 05 with RomRaider, per the 1st post of this thread. I cannot speak for 08+ cars.

[seabass07]

I don't remember a 3rd thing to adjust. I just upped RT and rescaled the TP to match it. I also fine tuned it in the lower TP area since I was getting hard shifts while cruising. It is very smooth now. I didn't touch the 0-20 TP region and raised it in increments up to 50% TP as opposed to just a blanket 27.5%.

[seabass07]

I had no TP issue when adjusting RT on my 05 with RomRaider, per the 1st post of this thread. I cannot speak for 08+ cars.

 

 

What value were you logging for throttle? I noticed it with throttle plate position%. When I upped RT to the max, My TPP didn't go over 89ish and logging requested torque it would not go above 408. As I reduced the peak to closer to 408 but still over, throttle plate % increased the closer it was to 408. When I made the max 408, TPP went to 99.7 which is the same as I get with stock RT. This is on my 05 ecu.

[ClimberDHexMods]

Throttle Plate Opening Angle (2-byte)** (%)

 

and

 

 

Throttle Opening Angle (%)

 

Both 100 +/- .5ish

[seabass07]

That is interesting. I was able to see my actual TP% correlate to where 408 was on the TP map. It was most noticeable at 40% 35% increases. When I ran 30% like you did, my TP was in the upper 90s. I also ran lower boost and wastegate due to less throttle. Now

 

Have you logged RT to see what the max numbers are?

[ClimberDHexMods]

I have not. My transmission is going to get replaced soon, so I'm not making any further progress on this. That and I am working on MegaShift, so I don't see a stock TCU too far out in my future. With MegaShift there are two more code tweeks I need before the controller can be ran with zero hardware modifications. We are getting there.

[seabass07]

I'm much more interested in your project than the RT tables. Keep us updated!

[ClimberDHexMods]

As it stands now you could buy a MegaShift controller, and the current code can be setup to run the transmission very well (untested on a 5eat though). But you would have to convert the inhibitor switch outputs (High or Low voltage for each P R N D) to a single variable voltage wire with external hardware. You would also need to add external hardware to make the extra shift solenoid outputs work properly. I am compiling a list of alternative edits to the code so that you would only need to make minimal or no modifications to the controller, which would be ideal since I know jack about making fancy circuits with SMT... But it requires that Lance actually make the changes, and he has already done a lot for us as is. But it is my January obsession, and it may easily spill into February since it's kind of a necessity with a stock 5eat seeing an eventual 500chp with E85.

[seabass07]

Have you figured out what you will do about the transfer clutch?

[ClimberDHexMods]

The center differential clutch/solenoid... I'm going to leave it alone and run it unlocked until I feel comfortable to take on a new project. Down the road I might try to run a simple controller. It is probably possible to write code for MegaShift to do it. Inputs are TPS, brake sense, and lateral G sensor. Output is PWM to the solenoid, but simple ON/OFF with a resistor in series will probably be sufficient. Therecis also the Spider DCCDPro controller for the STi. It is probably the best one and would work well and would require little or no tweeks. If enough 5eat MS converts wanted him to make a controller specific to the 5eat, he would probably do it. Depends if his is ON/OFF or PWM output, etc.

 

I am still learning about a lot of this, and am far from completely understanding it yet.

 

Frankster knows a lot more than I do, but he is going the RWD/AWD route with a simple switch.

[motorbykemike]

i have been following this thread since the beginning as i am i need of some 5eat attn as well ..

 

i have some questions ..

 

1 : can the aspects of the tranny being attended to here be tuned using a cobb ap ?

 

2 : if the cobb ap cannot be used will the romraider tune interfere w/ my existing ap tune ?

 

3 : is there some way to lock the line pressure values in the "high" mode found when in the sport manual shift mode ?

 

4 : if i am correct the values are modified in part throttle only ?

 

5 : what is "megashift" , what does it do , it it available for purchase & from who ?

 

 

 

car is my wifes , dd, it ate the turbo a few weeks back so i replaced/upgaded to vf52 , dw740cc injectors , greddy up , perrin 2 pc catted dp , & a cobb ap w/ etune to make it work ..

 

i am staying conservative w/ boost/power output but the already iffy trans is telling me to do something NOW , esp at part throttle dd shifts in drive . i do not expect it to live & am looking for another to replace it but i know the new used one will need to be setup properly , or should i say , controlled properly , if i expect some semblance of reliability .

 

ughh

[ClimberDHexMods]

1) I believe so. But we're still not sure what or how much of an affect it has. We don't yet completely understand the TCU shift line pressure logic. Progress on this has completely stalled the last few months.

2) This requires deeper research in the dual AP/RR tuning threads, since you don't want to accidentally lock out your AP

3) Yes: cut the line pressure wire. You will get lots of dash lights though. But it will be wide open line pressure. Or you can splice in a resistor in the line pressure wire. This takes trial and error. It has been discussed in other 5eat threads, but as usual few people actually tried it. But it has been done several times.

4) We don't really know what it does, but one user claimed a definite improvement. Who knows.

5) It is a general purpose control board that can be setup and programmed to shift and control a transmission. No one has tried it yet on any 5eat, including Nissans and Infinitis. Frank_ster or I might be the first to actually set it up on a 5eat, since the TCU has not been hacked

http://www.msgpio.com/manuals/mshift/index.html

http://www.msgpio.com/forums/viewtopic.php?f=4&t=133&sid=3d1a9d5683271e98abca6819fd2bad63

 

The 5eat TCU control logic is so sophisticated compared to the MegaShift capabilities, it is hard to tell exactly how it will turn out. We will see.

[motorbykemike]

thanx , in response to q/a # 3

 

where is this wire , how do i identify it , what resistor do i use , who has done it & where do i find info on the process/results ?

[ClimberDHexMods]

thanx , in response to q/a # 3

 

where is this wire , how do i identify it , what resistor do i use , who has done it & where do i find info on the process/results ?

 

You're killing me smalls, you're killing me. Since you're nice:

 

 

P/L Solenoid Output B54 Pin 9 Line pressure

 

Remember this is backwards of all the other solenoids. Cut = full open pressure, as a safeguard in case it actually does get cut. In normal operation is never even gets close to full open so I wouldn't actually cut it. A resistor will tone down the current (or is it voltage?).

 

In this thread http://legacygt.com/forums/showthread.php/5eat-tcu-reverse-engineering-136175.html?t=136175&highlight=resistor

 

Search for the word "resistor". http://legacygt.com/forums/showthread.php/5eat-tcu-reverse-engineering-136175.html?t=136175&highlight=resistor

 

This in general is how you find things http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=5eat+resistor#q=5eat+resistor+site:legacygt.com&hl=en&safe=off&prmd=ivns&ei=hXFITc-xIsT_lgfKxfj0BA&start=10&sa=N&fp=fca90e9507624f80

 

You may need a VagCom cable and download FreeSSM so you can reset your 5eat TCU's learned parameters, or to just clear the over-pressure code if you put in a resistor that raises line pressure solenoid current above the TCU's threshold of non-CEL.

[Apex-XT]

I've been following this thread with interest bc of very rough/hard shifting in my OB-XT/5EAT. 1st to 2nd sometimes revs high and slams into gear, jolting the car so badly I'm concerned it will damage the trans. I noted with great interest your comment that you suggested FreeSSM could reset the TCU's learned parameters. Is that the 'Clear Memory' function or something else? I don't want to kill my TCU. Any thoughts on whether this would help?

 

Background: I've already performed several, over about 30k miles each, trans flushes with official Subaru AT fluid and BG AT+ and most recently changed the spin on filter but the problem seems to be getting worse. It happens more when cold, but I know it has a tendency to shift harder when cold, but also happens occasionally when hot. I've consulted with my dealer who suggests another trans flush. I've also asked them reflash the TCU, but they don't have an option to do this in their computer. This is a last resort before going to an IPT TB build. Any suggestions?

 

I apologize for this side track on the thread. I'm trying all options before $800.

[gotsugg]

^^^To clarify, you have no power mods, nor a valve body upgrade, correct?

Mine does the exact same thing now and then. There is no pattern that I am seeing.

[ClimberDHexMods]

I've been following this thread with interest bc of very rough/hard shifting in my OB-XT/5EAT. 1st to 2nd sometimes revs high and slams into gear, jolting the car so badly I'm concerned it will damage the trans. I noted with great interest your comment that you suggested FreeSSM could reset the TCU's learned parameters. Is that the 'Clear Memory' function or something else? I don't want to kill my TCU. Any thoughts on whether this would help?

 

Background: I've already performed several, over about 30k miles each, trans flushes with official Subaru AT fluid and BG AT+ and most recently changed the spin on filter but the problem seems to be getting worse. It happens more when cold, but I know it has a tendency to shift harder when cold, but also happens occasionally when hot. I've consulted with my dealer who suggests another trans flush. I've also asked them reflash the TCU, but they don't have an option to do this in their computer. This is a last resort before going to an IPT TB build. Any suggestions?

 

I apologize for this side track on the thread. I'm trying all options before $800.

 

1) FREESSM will reset the longterm trans learned adaptations if you choose to, without wiping any of the base operating settings It's like what pulling the negative battery cable does as an ECU reset.

2) your trans may already have a worn clutch pack, in which case a VB mod will make it feel even worse in some instances, and may or may not prevent it from getting worse. Your trans is in fact slipping and then slamming into 2nd. I have the exact same problem.

The time to modify the VB is when the trans is in perfect condition. It's like a bra. Holds everything up great from the start to the end, but won't fix the sag if it's already there. If you have the money, the proper thing is to get augmentation so its back to good shape, and then maintain with bra. But some prefer to drop extra for bigger capacity / better service life if they're already in there (full IPT build). But for many this is appealing only in theory, and excessive in reality. Hope that makes it nice and easy to understand.

[Apex-XT]

^^^To clarify, you have no power mods, nor a valve body upgrade, correct?

Mine does the exact same thing now and then. There is no pattern that I am seeing.

 

Its running stock now. I had a Infamous1 Stage 1 tune running for a while, but never pushed it. The car is a daily driver. About 75 mi one-way with 150k miles in Denver. Even though it is a turbo, the altitude limits the output power considerably.

 

1) FREESSM will reset the longterm trans learned adaptations if you choose to, without wiping any of the base operating settings It's like what pulling the negative battery cable does as an ECU reset.

2) your trans may already have a worn clutch pack, in which case a VB mod will make it feel even worse in some instances, and may or may not prevent it from getting worse. Your trans is in fact slipping and then slamming into 2nd. I have the exact same problem.

 

Thank you for the clarification. I'll probably try the FreeSSM reset to see if that helps. Regarding slipping, wouldn't it attempt to shift at normal RPM and then take a while to 'catch' instead of rev to a high RPM, sit there for a couple of heartbeats, then shift, then 'catch'? Also, if it were slipping, wouldn't it 'ease into' it instead of slam? I've experienced clutch slippage before in an AT and this doesn't seem like it. But, I have no prior experience with 5EAT. Also, I get what you're saying about the VB mod.

 

So, is there a DIY or instructions on replacing the clutch pack?

 

Thank you both for your responses.

[ClimberDHexMods]

Thank you for the clarification. I'll probably try the FreeSSM reset to see if that helps. Regarding slipping, wouldn't it attempt to shift at normal RPM and then take a while to 'catch' instead of rev to a high RPM, sit there for a couple of heartbeats, then shift, then 'catch'? Also, if it were slipping, wouldn't it 'ease into' it instead of slam? I've experienced clutch slippage before in an AT and this doesn't seem like it. But, I have no prior experience with 5EAT. Also, I get what you're saying about the VB mod.

 

So, is there a DIY or instructions on replacing the clutch pack?

 

Thank you both for your responses.

 

1) The trans control logic is not as intelligent as a human would hope it to be, so it doesn't know precisely that it's slipping or not, unless there is a significant malfunction, or some calculated input is out of range. Reports on this forum show many folks with a particular shift, such as 2-3 or 1-2 being a bit slammy, so it's not unheard of. The TCU only has several speed sensors and on/off pressure switches to determine what it is doing. It tries to learn best it can, but it cannot learn around clutch pack wear past a certain point. I do not know much more than that. But I plan to figure out if there is some sort of clutch pack pressure ramp angle, which would probably explain the slight slip and subsequent slam. I have heard this version of "slipping" described re older gen transmissions on other cars.

2) No one outside of a dedicated trans shop has done any sort of rebuild on our 5eat other than a center diff assembly swap. It is definitely an advanced procedure, with little-to-no margin for error. That said, where there is a will there is a way There are diagrams showing how each clutch pack and planetary gear set is assembled individually, but I have not seen rebuild instructions anywhere. I would love to get my hand on them though.

[Apex-XT]

Thanks ClimberD,

 

If I could find a 5EAT rebuild how-to, I'd make a DIY for the forum. I've searched here and haven't found anything beyond Frank-ster's center diff build. I've found complete 5EAT rebuild kits for sale, but no instructions. It may be as simple as disassemble, reassemble in reverse order with new parts. But I don't want to attempt it without some indication that it works like that. I'm not uncomfortable in the innards. Just built out a BMW motor - bored, stroker crank, Schrick cams, head work, etc. for my old '94 325i Convertible week-end driver. If I find instructions I'll send to you.

[ClimberDHexMods]

Thanks ClimberD,

 

If I could find a 5EAT rebuild how-to, I'd make a DIY for the forum. I've searched here and haven't found anything beyond Frank-ster's center diff build. I've found complete 5EAT rebuild kits for sale, but no instructions. It may be as simple as disassemble, reassemble in reverse order with new parts. But I don't want to attempt it without some indication that it works like that. I'm not uncomfortable in the innards. Just built out a BMW motor - bored, stroker crank, Schrick cams, head work, etc. for my old '94 325i Convertible week-end driver. If I find instructions I'll send to you.

 

That would be perfect. Likewise if I ever find anything I will send it to you. But take a look in the 6000+ page factory service manual. Blow-ups of each trans component. That would be half of it. I hear you will need special spring compressor tool and things that hold the clutches in a specific alignment, etc, but I also see plenty of people figure their way around needing half the special tools out there.

 

I have a spare old 5eat, so if you want to come down to DFW we can tear it apart and see about putting it back together the way it came apart. Also if you can find a 350Z/G35/Titan 5at teardown of any sort, or any Jatco literature on their 5at rwd gen transmissions, that would be useful as well. The center diff housing was just slapped on as an afterthought. The info on the assembly of the main case is where all the goodies are.

[ClimberDHexMods]

Apex-XT, I'm looking up 5eat rebuild kits as we speak.

[fishbone]

Apex-XT, is the transmission holding the gear for too long, or do you feel it let go and it slips up? There is a difference. The line pressure is high in 1st gear so if it holds it and shifts at high revs, it will shift very firm in 2nd.

[motorbykemike]

a good friend of mine owns a tranny shop . he is building a 5eat to go into one of his race cars , it's not a subaru or suby powered , i will be helping him w/ the project .

 

i have informed him of everything i have seen here & he is on it , ipt , transgo , 350z , ect . he may use pcs box or cars motec to run it but not sure yet . when something happens i will advise .

 

he is doing research on the vb & it's controls now & may come up w/ something new & improved , bright guy , i have confidence .

 

my trans is next in line after his .

[Apex-XT]

Apex-XT, is the transmission holding the gear for too long, or do you feel it let go and it slips up? There is a difference. The line pressure is high in 1st gear so if it holds it and shifts at high revs, it will shift very firm in 2nd.

 

Thanks for the input Fishbone. Yes, it revs high, holds there for a heartbeat or two, then slams, sometimes very hard, into 2nd. I get a little of the same in the 2nd - 3rd shift, but not nearly as much. I stated elsewhere that I didn't think it was slipping necessarily, as it catches real good when the 'slam' happens. It seems to me to be more of a delayed shift problem. But, I don't have any experience with a 5EAT, so it could be as ClimberD suggested and the clutches are slipping, then grabbing.

 

FWIW, I reset the learned memory using FreeSSM over the weekend. It has not solved the problem as I'm still getting some slamming in the 1st-2nd, and a bit in the 2nd-3rd shifts. However, I haven't gotten a very hard one, yet. My gut tells me that it didn't solve the problem.

 

Any solutions to the line pressure issue?