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How to Tune 5EAT Line Pressure


ClimberDHexMods

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I spoke with a respected Subie shop in the area and one of the comments the service guy focused in on was line pressure. He suggested that they could pull off a line and test the pressure with the tranny still in the car to see if that could be the problem.

 

Resetting the learned settings with FreeSSM has not solved the problem.

300k miles, BNR 16g, CryoTune, 'Bullet-Proofed' IC, Motor rebuild @ 250k b/c of a cracked exhaust valve. Original 5 EAT. Oil changed religiously @ 3,000 mi.
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That's what mine does. There is a very slight delay with 1>2, and then slam. It began only after beating the piss out of the car while stage 2. I looked it up in the RE5R05A manual, and I'm 90% sure now the direct clutch is the culprit. It makes sense. Fish, we have a shift solenoid PWM initiating ramp angle for comfort, so there is a little pressure on the direct clutch for a moment, and then the grip quickly increases on the clutch pack. I would bet maybe $20 on this explaining the shock :lol:
[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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I believe slammy shifts were something addressed by SOA but I am too lazy to look it up. If the gears were slipping, you would definitely know (the car doesn't pull and it feels like it's in neutral).

 

Thanks Fishbone...

 

If I were an enterprising Subie driver with some skin in the game, where would I go to look this up?

 

I'm about to make an appointment with said Subie shop to test the line pressure. If that's it, I'm just going to purchase a new line pressure solenoid and pop it in and see what that does.

300k miles, BNR 16g, CryoTune, 'Bullet-Proofed' IC, Motor rebuild @ 250k b/c of a cracked exhaust valve. Original 5 EAT. Oil changed religiously @ 3,000 mi.
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Thanks Fishbone...

 

If I were an enterprising Subie driver with some skin in the game, where would I go to look this up?

 

I'm about to make an appointment with said Subie shop to test the line pressure. If that's it, I'm just going to purchase a new line pressure solenoid and pop it in and see what that does.

 

You google for TSBs (Technical Service Bulletins) regarding TCU reflashes to upgrade shotty TCU programming from the factory. Or you call ahead and see if your dealer's service department bothers to look up these kinds of things (some are lazy and don't) in which case you would not need to look it up.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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  • 2 months later...

Like anything, requires time to test, and there is never enough time. However, this is absolutely worth testing, so at some point I hopefully will.

BTW anyone can test this. Just make a serious change to your requested torque map, then watch or screen record before and after pulls of line pressure and other solenoids with FreeSSM. See if the TCU changes anything.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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I have leave starting next week, maybe at the end of the week(going camping at the begining) I will get to try this. I have a lot of stuff to work on besides this, but all I really need is an hour or 2 ....
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  • 7 months later...

Bringing this thread back to life...thought i'd chime in here.

 

I have been working on tuning my G35x, which has the same tranny as the LGT's 5EAT. We discovered that we can't change the shift points per-se, but adjusting the requested torque tables has resulted in firmer shifts, both at WOT and normal driving.

 

I won't take credit for what I did not do, but another member on that forum added his RTq tables to my tune and it was certainly a great improvement; not too hard, but quick and responsive.

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Glad to know it works for you. I also felt a difference. Now that romraider can log trans parameters, i want to log the difference in line pressure to see how much of a difference there is.

 

To be honest (and I haven't logged anything from the transmission), I don't see how logging will help a whole lot here. I think the best indicator will be how it feels for you. As long as it's not slamming into any gears, whatever feels good for you should suffice (that's what she said :dm:).

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Upping the requested torque valve is old news at this point. Since RT directly correlates to target boost, early onset RT of 350 is all we can do in the ecu map to help with line pressure. However its not enough when running stage 3, we need more line pressure, thus the reason climberD has been selling his vb mod service for 05-06 lgt valve bodies.
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Upping the requested torque valve is old news at this point. Since RT directly correlates to target boost, early onset RT of 350 is all we can do in the ecu map to help with line pressure. However its not enough when running stage 3, we need more line pressure, thus the reason climberD has been selling his vb mod service for 05-06 lgt valve bodies.

 

Oh, I never said this was a replacement for a VB upgrade. But my point in bringing this back was that, if done correctly, it can certainly help with firmer shifts. I'm pushing around 300chp on my car.

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Yes. The tcu knows what the rt is based on the ecu map, it does help maxing out the rt but the tcu only recognizes rt of 350(or is it 380). If you were to set rt in the ecu of 400 the tcu would not know what to do with it. I'm at 300wtq and with the maxed out rt the tranny still hates shifting with all that torque. Inbetween gears is terrible for the tranny at that power level. Albeit the shifts are firmer, there still is slip time and heat build up. I would not feel comfortable wot it and letting it shift itself in D. I cringe because I know the clutch packs are hating it.

 

So i only wot when its in gear, and let off for a split second while paddle shifting.

 

Thus the wait for the 07+ climberD valve body mod

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No datalogs yet. But that's what I'm planning to do, since we can log line pressure along with pedal angle and rpm. We'd have to map the logged rpm and pedal angle values to figure out what the RT is though.

 

BMX, I don't think it's old news since in this entire thread I'm the only one who seems to have noticed any difference. I don't think anyone is doing this other than me and maybe a couple of others.

 

My tcu recognizes up to 408RT. Anything above that and it will reduce your throttle plate to whatever correlates to 408 in the map.

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It is old news, climberD mentioned it a while back, and also in the TCU reverse engineering thread its been discussed, hell my tuner told me about it too. Also, if your open source tuned, your RT is maxed to begin with when in open loop, as to what value youre tuned to may vary. Most OS tuners know this as well. Regardless whether its old or new news, it's not enough to hold when stage 3...thus why the vb mod even exists. Auto trannys, and manufacturers know that when rt is up so is engine output so for the line pressure to not go up is boggling. I noticed a difference once my tuner mucked around with the RT and rev limiter, it shifter firmer and sometimes jerks you back, that was with upping the RT earlier on in the table
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My tcu recognizes up to 408RT. Anything above that and it will reduce your throttle plate to whatever correlates to 408 in the map.

 

There's a table for that... Have you upgraded to 521R yet? ;)

 

   <table name="Maximum Requested Torque" category="Drive-by-Wire Throttle (DBW)" address="CA8BC" type="2D" level="1" scaling="rawecuvalue">
     <description>Requested torque values will be limited to this maximum.</description>
     <table name="Maximum Requested Torque" type="Static Y Axis" elements="1">
        <data>Maximum</data>
     </table>
  </table>

MaxRT.PNG.c618bfc0497796bd97472af246092e7f.PNG

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There's a table for that... Have you upgraded to 521R yet? ;)

 

   <table name="Maximum Requested Torque" category="Drive-by-Wire Throttle (DBW)" address="CA8BC" type="2D" level="1" scaling="rawecuvalue">
     <description>Requested torque values will be limited to this maximum.</description>
     <table name="Maximum Requested Torque" type="Static Y Axis" elements="1">
        <data>Maximum</data>
     </table>
  </table>

 

I have the rom ready. Just need to flash it. Looks like ill be doing that tonight. That makes things a bit more interesting

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I already have it set to 408 so i doubt there would be a difference. My guess is that it would default to 408 if it cant use anything higher. But i would like to try higher numbers just to see what happens.
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