MY07 GT Spec.B ECU Upgrade / Tune & light performance mo

[Boxer]

Adam and Tehx , you are both on the money with SI drive mapping and changes.

As has been covered before and proven - SI drive in a manual transmission Lib ONLY changes engine throttle relationship to pedal travel and that is how Subaru control boost. (boost is not limited in I mode - only throttle is, but the result gives a max boost in a stock GT of 7PSI, due to the limited throttle allowed)

More correctley the pedal controls the 'requested torque' to the ECU and the ECU adjusts the actual engine throttle to the optimum point depending on RPM, load etc to provide the correct torque output for that pedal position. Therefore there is the absolute possibility that flat to the floor will not give maximum butterly opening in the throttle body until all the parameters are right to give the best torque. It allows the ECU to make the best decision of how to get the most torque in any situation and take advantage of venturi effects and the like in lower rpm ranges where a sudden throttle opening can actually 'bog' the motor.


Anyway the long and the short of it is when a tuner adjusts SI drive - its just the throttle/pedal relationship. If you want to limit boost to say 14PSI in S mode whilst S# gives 16PSI then the throttle map needs to be set to max 85% (just an arbitrary figure from my backside) at full pedal.

The boost and throttle maps are inter-related in the ECU in such a way that at any given point in the throttle axis = a set parameter in the boost map

For this reason I dont like S# mode in stock form as full throttle at 70% pedal means the last 30% travel does nothing and only makes the pedal too sensitive for heel toe driving and coming off the accelereator fast enough between gears on full throttle changes

[dwayne]

I too would like so more info on the SI modes of operation. I noticed that the MRT site has more info on the Liberty's and mentions that they can now change the boost levels with ECUTek. A friend who recently purchased a second hand liberty, with the MRT tune, informs that there is 11psi on S and 15psi on S# - that I need to confirm.

I would like to know if the SI drive changes the throttle response in such a way that it reduces the throttle travel and/or throttle opening/response over a period of time. In the first instance you can think of throttle travel as 0% (not pressed down) and 100% (foot to the floor). In this way S# would take the 80% point and remap that to 100% of engine throttle - electronically. This would mean that the last 20% of movement in the throttle - does nothing. The other method (using a factor of time) would work like this. You press the throttle to 100% and the ECU brings the engine revs up to 100% in say 2 seconds. In S# mode that 2 seconds would be reduced to say 1.5 seconds. The ECU would use a single parameter for delay or a lookup table if the delay were to change, relevant to throttle position. It's an electronic throttle so you have control over both the throttle travel and how long (delay in time) it takes to respond to a given input.

When I look at the little SI graph on the dash I think the y axis (up and down) is the throttle opening 0% to 100% and the x axis (right) is time. It then seems that 'I' mode both reduces the amount of throttle opening you can have, and throttle response (over time) is extended out. S and S# give you full throttle opening but the time taken to get that full throttle is slightly reduced in S#.

So in effect the only mode that changes throttle travel is 'I' mode - it makes the 100% point of throttle movement (foot flat) equal only about 75% of throttle opening. S and S# always give you 100% of throttle opening, but adjust the time it takes to get to that point.

OK, firstly, [I] mode only gives you max ~30% throttle ! Which is why it feels like such a sedated lethargic slug

Now, your other thoughts above are pretty spot on. Max throttle both S & S# is 100%, and as the pretty graph on the dash indicated, S# is effectively responding faster. I've been checking this out with the ECUDataScan, one of the things it reports is throttle %, and also accellerator pedal angle. I haven't measured them both together (yet), but basically for any given accellerator pedal angle, the amount of throttle being fed to the engine is different based on the mode. For example, a light press might give 10% in [I], without changing the accellerator position, a switch to S will give maybe 22%, but switching to SI will give say 47% in the same throttle position. It seems to behave like mouse accelleration on a PC - the higher the setting, the steeper the accelleration curve until it reaches full speed.

I'll do some tests on my way to the gym shortly, and log both accellerator pedal angle and throttle opening together, that should give a map of what's going on. Will post it up later tonight.

Cheers

Dwayne

[smythie]

dwayne, keep in mind Boxer's comments above. Your throttle opening on a non-fettled car will not necessarily consistently match accelerator position

[tehx]

Agree with the comments about 'I' mode; it's pretty useless, if not somewhat dangerous. You get to know the characteristics of your car in S mode, like overtaking ability with respect to power and distance etc. Then try pulling out into traffic, or overtaking a semi, while in 'I' mode suddenly you find yourself in a position where you don't have enough of the good stuff to do so. I guess it might be useful if, for instance, you loaned the precious GT (with 15psi of boost) to grandma for her weekly shopping run. Then, it just might prevent her from ploughing the thing into a crowd or something.

I too prefer S mode for drivability however since the ECU flash/tune the characteristics of S mode are now quite different to the factory setting. I’m assuming Paul tweaked this mode while tuning. It seems to have a more aggressive response (more so than S# now). For heel-and-toe I find that I only need to tap it - short and sweet. Its almost like it has been setup for heel and toe. In S# mode I have to tap further and for longer. In some ways I think S and S# feels swapped around.

[GTB Liberty]

I too prefer S mode for drivability however since the ECU flash/tune the characteristics of S mode are now quite different to the factory setting. I’m assuming Paul tweaked this mode while tuning. It seems to have a more aggressive response (more so than S# now). For heel-and-toe I find that I only need to tap it - short and sweet. Its almost like it has been setup for heel and toe. In S# mode I have to tap further and for longer. In some ways I think S and S# feels swapped around.

This is one of my concerns with any "tune". The drive ability factor after a "dyno" tune sometimes does not always equate to "in the back" road driving feeling right.

Another +1 on "I mode being useless" excepting "fuel missions" on long range drives when the S# steering wheel button is my friend. Around town I can barely get 50 Km in 5 gear without lugging and 60 in 6th in I mode without giving up. In S mode its not an issue. Interestingly, my fuel usage around town "granny short shifting" is better in S v I mode.

[parso_rex]

Woud you like me to post up the relevant maps to show you the SI drive's workings. A picture tells a thousand words

[moggy]

Another +1 on "I mode being useless" excepting "fuel missions" on long range drives when the S# steering wheel button is my friend. Around town I can barely get 50 Km in 5 gear without lugging and 60 in 6th in I mode without giving up. In S mode its not an issue. Interestingly, my fuel usage around town "granny short shifting" is better in S v I mode.

Why would you be using 5th & 6th gear around town? I only use them as overdrive gears when i'm highway driving.

Bob.

[GTB Liberty]

Another +1 on "I mode being useless" excepting "fuel missions" on long range drives when the S# steering wheel button is my friend. Around town I can barely get 50 Km in 5 gear without lugging and 60 in 6th in I mode without giving up. In S mode its not an issue. Interestingly, my fuel usage around town "granny short shifting" is better in S v I mode.

Why would you be using 5th & 6th gear around town? I only use them as overdrive gears when i'm highway driving.

Bob.

It's called being a misery old bastard when there's no chance of utilising the power

Regardless it was to illustrate that I mode isn't all that it should be.

[GTB Liberty]

Woud you like me to post up the relevant maps to show you the SI drive's workings. A picture tells a thousand words

You had to ask?

Yes please

[parso_rex]

OK here you go, these are examples of the 'requested torque' tables located with in the Liberty Rom and for that matter all of the later models with SI drive. In this case its an 08 Liberty Spec B wagon . Look at the Sport and Sport Sharp modes and notice the 350 raw ECU value don't try and quantifiy this as anything just think of it as your engines peak torque output with the number representing as decreasing level of torque as they lower to the left. Now look at the Intelligent mode notice the maximum on the right hand cells, its down somewhat on the two 'Sports' modes. This effectively means you''l not be seeing the full amount of torque here with normal driving (this isn't actualy true truth be told.... hold the throttle to the floor and it will switch ). Also notice the amount of pedal travel in each of the three tables, you'll see that there is quite a bit of difference. This is what gives you your throttle feel if that makes sense. You can change this too btw I could swap thing round all over the place and really make it unpleasant. I think they are pretty good as they are, maybe you'd say customise one lets say 'Sport' to suit your usually driving style and leave the other two. I actually find 'Sport to be pretty close to be honest.

This torque limiting technique is not just a Subaru thing either. You should see some of the software we are getting for The Euro branded Cars its very common. I used to think that big capacity NA cars were all tuned to their limit but no, there are big gains for example in the VW R36 and Mercs where they use torque limiting to effectively clamp the car back so it doesn't 1) risk warranty claims relating to faulty transmissions or 2) make their higher end models look less inviting .




Hope I haven't bored anyone to death
Mark

[smythie]

very interesting. I didn't make out in your comments whether you had played with those tables at all. Did you? If so, what areas did you change?

[sundayDriver]

I just got back from Sydney. I got my 07 GTB tuned at Pulse racing today. I got 164.3kw atw and 480nm (done in 4th gear).

what's really intersting is the before chart. it has two valleys over the rev range and this was a result of the ecu trying to pull back the unexpected boost after fitting phat's dump pipe.

when I work out how to post up images, I'll put up the chart.

[sundayDriver]

Here is the before and after power runs:

pulse tune chart

pulse_tune1s.jpg (251.26 KiB) Viewed 4004 times

Red solid line = before power
red dotted line = before torque
blue solid line = after power
blue dotted line = after torque

[gordy]

sundayDriver, Can you give some details please. What model is your car, auto or manual, and besides a phat DP any other mods?

Cheers

Gordon

[Arith]

Tan, is your Liberty a manual and do you have a centre pipe & muffler as well as a pod intake? Just curious about the 30kw difference between your tune and Trieu's with those 3 mods being the only difference.