DSC didn't catch 2nd gear power shift
 

I had a peculiar experience this Labor Day weekend. It was raining here in New York most of the weekend.

I know from experience that DSC checks wheelspin launches in 1st gear from a standstill, but this did not happen in second gear. I found an isolated stretch of road and stabilized my speed at 25 mph. I then revved to 7000RPM and engaged the clutch rapidly (but didn't drop it) still on second gear. The wheels spun out like crazy and I sweeped the road right and then left with the RX-8's rear end as I regained control with 2 corrections. The DSC never came on.

Has this been documented? I couldn't find one on this forum. Is this normal?

I am sure the Mazda tech will love having to recreate that scenario. I think the owners manual covers what happend to you.

It still doesn't explain why the DSC checks a wheelspin on 1st at standstill and not on 2nd in motion.

BTW, this was a voluntarily induced wheelspin on an isolated road to check DSC at a relatively low speed, in case anyone thinks that it was a reckless maneuver.

After the shock wore off you had a big smile on yout face? :rock:

I thought I smelled clutch. :p:

I've noticed it allows a bit of wheelspin at times, usually when going relatively straight and especially if it's a little wet. It kicks in more quickly when I encounter an over/understeer condition.

Also, I was under the impression that a power shift was an upshift (usually at redline) without clutch.

For some reason this reminds me of My Cousin Vinny. ;)

I actually had a very confused expression on my face since I was fully expecting the DSC to kick in and prevent the fishtailing. From what I understand, part of DSC's algorithm is to calculate the difference and the rate of change in the difference of all the wheels and if one is excessively off, then the DSC kicks in. Clearly in my case, the rear wheels were spinning way faster than my front wheels, which were travelling at a low speed.

Sorry my mistake about the term. It wasn't a power shift. Is there a term for when you rev up the RPM and engage the clutch in the same gear, essentially urging the engine into a "fatter" part of the powerband?

Yeah, clutch dumping, it's what drifters use. As you're going into a corner, release the clutch, rev it up a bit, then dump the clutch again - rear end breaks loose and you're in a powerslide. Try it a couple times around a traffic circle. It's kinda fun, though your clutch hates it. :)

You're operating the vehicle outside the parameters of how the DSC was designed to work. What you're doing does not fall under normal vehicle operation(i.e. emergency manuevers in slippery conditions). That's why they put the warning in the manual. People don't drive like that normally so the DSC algorithms probably don't do anything when it's outside of the parameters.

Thanks for the answer.

It would be nice to know what those parameters are, but I guess the algorithms are somewhat of a trade secret.

That's great news then. We can keep the DSC on and still have fun.

Actually, the DSC did kick in, you just didn't notice it because the algorithm is meant to make sure that it's intervention won't cause any horrible side effects, like a pendulum effect for example.

Here in UK, every RX-8 owner is invited by Prodrive (the company that made the rx-8 PZ and improved the RE040's original CZ design into the RZ).

They take you on their skid pan which is meant to simulate ice conditions.

With the DSC engaged, they show you how to provoke a power oversteer. But no matter how hard you try to spin it, the car just hangs in the power oversteer, eventually straightening up as you unwind, without pendulum side effects.

Repeating the same manouvre several times with the DSC OFF, the car can be spun very easily if provoked.

So, the DSC is configured to allow a certain degree of side away action, without compromising the recovery from it.

All true, but I don't think that revving the engine to high rpm and dropping the clutch constitutes a normal driving parameter. When you do the wet skidpad tests, you don't rev it in neutral and drop the clutch do you? They try to simulate normal driving conditions (i.e. taking a wet corner too fast or using too much throttle coming out of a corner). I believe one of the techniques drifters use is the nuetral high rev-clutch drop to provoke oversteer. The engineers probably lump all these into the "agressive driving category" so DSC probably won't save you if you do anything like this.

uh,

traction control controls wheelspin... did you have it turned off???

traction control and dsc are two different things..

beers :beer:

A "power shift" as I know it is not the same as how you describe it. To ME, a powershift is changing gears in the conventional fashion but for not letting up on the accelerator pedal at all... Or maybe that's a "speed shift". I think they both describe the same thing.

Upshifting (or downshifting) without using the clutch? It can be done (I did this with an old car of mine to see if it could be done), but I don't think your tranny will last long if you do so, even with careful rev-matching.

Marisa Tomei(spelling) :yumyum:

Yes it does! You weren't hydroplaning at a dead stop.

Isn't a power shift something one does with an auto tranny?