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, Sat, 26 Dec 2015 09:44:29
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I'm not sure what you're trying to say exactly, by pointing out the percentages. There are going to be two percentages involved: wheel spin related to all other wheels, and wheel spin related to the opposite wheel. Let me clarify what I'm talking about, because I must insist this discussion is important.
In the Viggen, the TCS feature really has two functions:
1) "e-diff" If one front wheel is spinning faster than the other three, it applies the brake to that single spinning wheel to transfer torque to the opposite wheel. Assuming the other wheel has traction, you will notice an increase in acceleration.
2) "very basic stability" After applying the brakes to the spinning wheel, if the opposite wheel now begins to spin, it applies the brakes there briefly as well. If this repeats much AT ALL, or the front wheels collectively spin more than the rear wheels, it cuts the throttle COMPLETELY for about 1 second. The idea is to keep the front of the car from suddenly losing complete traction.
It is this second function that is nearly broken in the stock ECU. If you're trying to make it up a hill or accelerate from a stop light, you will go NOWHERE. It tries applying the brakes maybe 1 or two times, then cuts the throttle 100% and there is nothing you can do about it.
With the JZW tune, I believe the throttle cut is either disabled completely, or only comes on at much greater throttle positions. I can place one wheel in the ice and another on gravel and just go for it. Of course the wheel on ice will apply the brake like normal, but then it will allow some wheel spin on the opposite wheel, which is going to be expected to some degree. It will gladly grab wheels back and forth all day long, searching for traction, without cutting the throttle at all.
What this translates to is you now you CAN make it up those steep, snowy hills. Some amount of wheel spin is helpful on snow, as long as the spinning is kept under control (torque can be transferred to the wheel with more traction). Leaving a stoplight, I just place one wheel in the shoulder a little and go. You can feel the car get slingshot along as it applies the brakes to the wheel on ice. No throttle cut, ever. Just go.
Using the brakes to create a "virtual" limited slip differential is quite common and VERY much improved compared to an open diff. Audi's Quattro system uses a torsen diff between the front and rear, but only an open diff and braking left to right. It is quite effective. It is not perfect, but reduces weight and is more reliable than complex AWD systems with viscous clutches, limited slip diffs, etc.
Audi's system adds stability control, or ESP. Pressing the ESP button disables the Electronic Stability Program for acceleration, but not when braking. It does not disable the electronic diff function ever.
I think this is where SAAB got it wrong. Pressing the TCS button once should disable the throttle cut feature, but leave the electronic diff function enabled. Holding the button down for 5 seconds should fully disable the electronic nanny...
I assure you I have no reason to push any one tune over another. But I must be very adamant that the JZW tune I got is great. I'd never give it up. With the stock tune, I would drive around with TCS disabled, and actually had a habit of starting the car and turning it off right away, EVERY TIME. Now, I can't remember the last time I turned it off.
posted by 216.67.47...
, Tue, 22 Dec 2015 11:20:54, Sat, 26 Dec 2015 09:44:29, Mon, 28 Dec 2015 10:10:05
, Sat, 26 Dec 2015 19:24:04
, Tue, 22 Dec 2015 12:18:04, Tue, 22 Dec 2015 14:58:58
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