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How to Tune 5EAT Line Pressure


ClimberDHexMods

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Would be great to have a quick and dirty system to match RT colums and TP header values to turbos, but I can't figure how since the RT table changes by accelerator angle, not RPM. If anything, it would be better to make all the values in any column the same, or even high RPM-biased, which is the opposite of what we get now. We also don't know how mph affects the line pressure solenoid duty cycle calculation...

 

Are you talking about on the fly (as in ECU opening the throttle more or less depending on boost) or pre-configuring the tables to match your turbo? Is the second, why not now? Both tables select the "Y" axis peramiter based on rpm. Thus, you an go tweak your part throttle settings to try and match the actual torque your car produces

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If all values are the same for all RPM in each TP angle, then in theory the LP will increase only with RPM and TP angle. I'll play with that as well and see what happens when the RT table is very different from the TP table.

 

I would like to see those raw values as well. Maybe they will give an indication as to how much effect on LP they have.

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Are you talking about on the fly (as in ECU opening the throttle more or less depending on boost) or pre-configuring the tables to match your turbo? Is the second, why not now? Both tables select the "Y" axis peramiter based on rpm. Thus, you an go tweak your part throttle settings to try and match the actual torque your car produces

 

Talking about rough pre-configuration.

 

Both X and Y axes would need to be tweaked, but I don't think RPM will emerge hugely important in this relative to TP. Or so is my off-the-cuff prediction for my final "ideal map." Torque is much more a function of throttle angle than RPM. We only think RPM is the big variable because we hold throttle angle at 100% constant. Change throttle angle at all and it throws the torque curve right out the window.

 

I would love to keep on guessing, but I really think the next step is people just logging and tuning by shift shock preferences, sharing, and then someone coming up with a rule of thumb AFTER. At least we know what setting works well for a stock car...

 

If all values are the same for all RPM in each TP angle, then in theory the LP will increase only with RPM and TP angle. I'll play with that as well and see what happens when the RT table is very different from the TP table.

 

I would like to see those raw values as well. Maybe they will give an indication as to how much effect on LP they have.

 

Don't forget about mph. We don't know what that does to line pressure solenoid duty cycle yet. It's a compensation likely made in the TCU. You can't tune it at present, but know that it will be doing something when you go out and drive and take logs.

 

Just realized, RPM logged can be referenced against time to measure shift time... sort of. So we CAN QUANTIFY LINE PRESSURE TUNING.

 

But I'm going to do it by feel :lol:

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I was just going to log rpm and speed to time the shifts. It should be a decent resolution that way. The thing is that MPH and RPM are always going to be related based on the gear.

 

Good call, but you still need to log the Y axis of the Requested Torque map to accurately tune anything area in the RT map other than coasting and WOT.

 

Edit: Eh RPM is hardly representative of mph below 3000rpms, and not quite accurate below 5500rpms. But you can probably ignore MPH 'until or if' you notice you get different shift feel at 20mph vs 90mph (on a closed private road :lol:) Resolution is king, so yeah I'm with you on dropping it, but not forgetting about it.

[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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Is it perportional? One could estimate the torque output based on the load (g/rev), so it might play into some sort of usefull calculation.

 

If that's true, we should bump this up anyway as we are making more torque.

I don't know about the automatics, but in a manual car bumping the RT value beyond a certain point prevents you from reaching 100% throttle angle in 1st and 2nd gear. I have it on good authority that there are some undefined tables that conspire in this. Again, no idea what the story is with a 5EAT as I didn't try increasing the RT values from the stage 1 map I installed.

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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Ha, found the long thread on NASIOC:

http://forums.nasioc.com/forums/showthread.php?t=1537010

The Dirty Details:

In Denso's (the company who makes the ECUs for Subarus) DBW system, there are two sets of tables. Roughly you can consider them input (Requested Torque) and Output (Target Plate Angle). The input tables take the position of the accelerator pedal (as percentage) and the current RPM and return a "Requested Torque" number. This Requested Torque number has NOTHING to do with the actual amount of torque the engine is making! It is simply an arbitrary value made up to make the programming possible. Changing the Requested Torque table will not make your engine stronger or weaker! The output tables take the Requested Torque from the input tables and the current RPM and return a Target Throttle Plate Angle (as a percentage). The ECU then moves the actual throttle plate to match the Target Throttle Plate Angle.

 

remember that the Requested Torque numbers don't mean anything real. They're just an arbitrary number. You could run them up to 5 million and get the car to drive exactly the same.

But maybe that only applies to MT cars.

 

You push the pedal, say, halfway. The computer looks at the "requested torque vs. accelerator angle" chart. It sees you having 50% throttle, and it sees the engine is at, say, 4000 RPM. It finds the number corresponding to that - in williaty's map that number is 20. Go look.

 

Now, it takes that number, 20, and looks at the "throttle plate target vs. requested torque" chart. It sees that the engine is at 4000 RPM, and so it picks the number associated with a requested torque of 20 and an RPM of 4000. In williaty's map, that is 20%. The ECU then attempts to open the throttle plate to 20%.

 

Therefore, pushing the pedal 50% yields a 20% opening at the throttle plate. The "requested torque" number does absolutely nothing after that math has been completed.

 

I'm not sure if I need to scale the rescale if that makes sense, in ATR since there is no rescaling of the table like RR does. Maybe opening it up in RR and editing it there would be easier.

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Here's input on the last 2 pages of that thread from some with an AT

I still have the strange side effect of high rpm shifts on the autotranny even when switching up the values on requested torque/TP angle tables.

 

I guess it can't be solved.

 

I guess I'll either live with it or maybe try out sa4b's values to see if that'll remedy it somewhat.

I thought i was the only one... i have noticed a increase in rpm's before it shifts.. before it would shift around 3500 rpm, now it's around 4000 rpm driving normaly..

Hmm, interesting. Try changing the Requested Torque->Throttle Position (output) table rather than the input table then. It's probably designed to shift at a given RPM based on how much torque you're asking for

It doesn't really make a difference. I've changed both and it doesn't do anything.

 

I really think that the TCU is looking at Accel Pedal Angle numbers in which the relation cannot be changed unless access to the TCU is available.

 

And here's something interesting

 

Sometimes my car will shift into 3rd when it's set to cruise going up hills and such, but will never shift back up to 4th gear when it's flat and has reached the target speed.

 

It's a TCU issue, i can only assume.

Actually, if the TCU is reacting to the DBW changes when in cruise, that implies the TCU isn't watching the accel pedal angle directly. Cruise doesn't move the pedal.
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Has any one actually checked the amount this changes the line pressure? You can use FreeSSM to see what it thinks it should be.

 

 

It doesn't look like anyone has done this yet. I wouldn't even know where to begin...but it may be worth playing with. Does it work through the vag-com cable?

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Nope. I've used all sp's of xp and vista. I'm missing something I think. I even tried installing it from a QT environment, but nothing. I just need to get my vag-com drivers working in linux. freessm looks ridiculously simple to use once working.
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Utc_ pyro, could you perhaps do an idiot-proof walkthrough like the one in this thread to help us use FreeSSM? I had never even heard of it until your thread...

 

I have a 4-day weekend starting now, so I should have time to play with it. I want to try this my self any way.

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I have Windows 7 64 bit on my computer and everything works fine. I also have the ebay Vag-Com cable. I can try and get some line pressure values with my current Requested Torque tune at +40% above stock if someone wants to get the stock values. FreeSSM only allows you to see the current values and records only the maximum value seen while the program is running. I say that whoever else does this should have their car at operating temperature before taking readings so we can keep it fairly consistent.
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