kyoo

iTrader: (29)

how does the behavior of the car feel?

awdboosted

iTrader: (30)

This tread is interesting.

I've had an old Gruppe-S ACD tune on my car and I've only driven my car on track with that tune. I've been fighting corner entry understeer for the longest time and I never thought that the ACD ECU could causing this. I'm going to try and change the ecu back to stock and see if it changes the way the car handles.

kyoo

iTrader: (29)

it's the gruppe-s acd, but i dont think stock is an improvement really. would try something else, ie ER.

NW IL = where exactly? i autocross in Rantoul quite often, you can drive my car and see how different the car behaves in each mode

psushoe

iTrader: (8)

Stock acd never fully unloads the center clutch pack. That means the front and rear wheel speed is never fully independent, which is what you want for turn in and off power or neutral throttle corner turning. Mitsu likely did that for stability. They also increase lockup with speed... also for stability.

RazorLab

iTrader: (8)

Care to share your defs? I'd like to see if it helps with defining the XML for my Evo 10.

Same case and ACD/AYC controller AFAIK. Evo 10 has a slightly different part #. 8631A040 vs 8631A028

kaj

iTrader: (60)

I had Tom do mine also. Things I've noticed:

* Car is much more willing to turn in. I was happy with how my car drove otherwise, so this eliminated the one complaint I had. It really surprised me, how well it works. I should have tuned the ECU long, long ago. No matter what setup you have, it's gotta be a huge help.
*On "lightest", tuned setting: Front tire spins under tight-corner, full-throttle acceleration (turn 11 @ Laguna Seca, AutoX, etc).
*On "mid" setting: My favorite, being on "200"tw tires @ 350whp. I feel like I can control the car better with gas pedal. I don't feel like I have to wait as long to start rolling on the throttle. Car used to be more "point and shoot", but now is more linear.

I haven't tried the more aggressive setting. Tom says I'd need a really sticky tire to make it work best and I never run more than a DOT 200tw.

When anyone who tracks/autoxes their car asks if they should do it, I tell them "Yes". No doubt.

kyoo

iTrader: (29)

it is pretty amazing how much it impacts the car's behavior when you're NOT on throttle

kikiturbo

sure, but I do have some older defs, did not work on it in a while because my car is off the road.. will dig up what I have..

we actually wanted to log the solenoid behaviour with regards to different inputs while the car was on a lift.. by manually moving the G sensors.. and see how that corresponds to the map. But that has to wait..

kikiturbo

I am not sure I can agree with your first statement. When you start the car the ACD valve runs some base current that is constant. However, that doesnt lock the central diff. If you put the car on brake test rollers it will happily turn each axle independent of each other..

kikiturbo

Some time ago we did some ACD/AYC logging in controlled circumstaces of my e9 to show some people that were developing their own torque vectoring system how the mitsubishis one works..

it is real interesting how it works..
in constant speed corner (skid pad) the ACD is open all the time. At lower lateral G the AYC is inactive too. As you increase the speed the AYC will slowly start ramping up the pressure. ACD is still open... However... the system is very sensitive to steering wheel speed, so change of steering angle speed...

if you do a quick steering input the pressure will ramp up immediately.. if the steering is smooth the ACD will be open all the time..

psushoe

iTrader: (8)

I'm talking about at speed, and I don't mean "locked". I mean it applies some pressure to encourage the wheels to spin at the same speed without locking them. You could spin them independently, but with some drag. When I first looked at the ACD tables, I noticed things like lateral g force decreased lockup on the center diff. That makes sense and encourages turning, because the rear wheels need to turn slower to follow a tighter line than the front (on tarmac without oversteer). Then I noticed that is true only at very low speeds. As speed increases, there are less things that decrease the level of lockup.

kikiturbo

ok, understood. But I have logs that show the same base minimal pressure all the way up to 0.97 G lateral in steady state cornering...

psushoe

iTrader: (8)

Have you compared stock acd programs from ayc and non-ayc cars? I wonder if they are different.

psushoe

iTrader: (8)

Also, what speed was the steady state g load?

psushoe

iTrader: (8)

Btw, not doubting your pressure logs, just trying to compare your findings with my general experience tuning my own car. Mine is based on car behavior change vs a change I made ina table. What did you use to log pressure? A sensor in the hydraulic line?