Boxster Question

[RobM77]

I found this comment in a review:

"This brings us to our only complaint about the car: It's drive-by-wire, so the PCM must close the throttle when the brake light switch closes"

full review here: www.motorage.com/motorage/article/articleDetail.jsp?id=15354

Is this true? Surely this means that you can't heel and toe, as you are pressing brake and throttle together when you do this.

I don't own a Boxster now, but I'm thinking of buying one and this worries me!

[anonymous-user]

I think, therefore this comment is bollox!!!!!!!!!!

[RobM77]

Thank god!

I can't quite see Porsche making a car you can't heel and toe in!

[mindgam3]

and even if the mechanicsm was true, it wouldn't be connected to the brake light switch! it would be connected to the brake servo or similar

[stefan1]

On the GT3 the throttle is cut if the brake is applied at the same time. However, this does not apply whilst the clutch is depressed, thus facilitating heel and toe. I would imagine the system on the Boxster is the same.

So it just means left foot braking is out.

Kind regards

Steve

[Don]

For a start PCM and PSM are different systems.

PSM being the "traction control" one. PCM being the phone (and Sat Nav etc)!

In my Boxster (986S) I can brake as hard as I like clutch in or clutch out and blip the throttle as much as I want - no problem at all.

So if you're worried about not being able to left foot brake to facilitate early throttle, or not being able to heel and toe to smooth out downchanges then don't worry. PSM does not get in the way of that. If you fancy a Boxster - I can highly recommend them. I've had two and will likely get another - if I don't decide to change to something utterly different and get a nice pre-depreciated Turbo.

PSM does a number of things but the main one is to brake opposing wheels in the event of a slide. It can also reduce throttle to assist in recovering grip after losing traction. The system is designed to cut in really quite late - so you can actually get the car drifting with it switched ON. Its only if things get out of hand that it steps in to save the day - which it does remarkably well.

If you want to get seriously sideways you can always switch it off too...

If you get one - ENJOY!

[DanH]

The drive by wire does let you apply a bit of throttle before cutting power when the brake is applied, but even mk2 GT3s will cut the power after this brief period. I think you can then lift off and reapply the throttle and it will then work, but I've not tried. There is some discussion of this on rennlist and its true for all modern Porsches with drive by wire.

[RobM77]

blimey - and I thought Porsche built driver's cars!

So I can heel and toe, that's one box ticked.

What about throttle response? All DBW cars I've ever driven have a delay on the throttle, making them useless as driver's cars and actually quite dangerous when driven quickly. This applies when coming onto the throttle, and also when coming off it...

What about left foot brake spin correction? If things go pear shaped on track and you're going to spin, normally in a RWD car a jab on both pedals recovers even the most perilous situation. Does this mean I can sue Porsche when I spin into a barrier at the ring that I would have otherwise avoided?

[Don]

RobM77 said:

blimey - and I thought Porsche built driver's cars! So I can heel and toe, that's one box ticked. What about throttle response? All DBW cars I've ever driven have a delay on the throttle, making them useless as driver's cars and actually quite dangerous when driven quickly. This applies when coming onto the throttle, and also when coming off it... What about left foot brake spin correction? If things go pear shaped on track and you're going to spin, normally in a RWD car a jab on both pedals recovers even the most perilous situation. Does this mean I can sue Porsche when I spin into a barrier at the ring that I would have otherwise avoided?

They do build drivers' cars. Test drive one. You won't be disappointed.

[DanH]

RobM77 said:

blimey - and I thought Porsche built driver's cars! So I can heel and toe, that's one box ticked. What about throttle response? All DBW cars I've ever driven have a delay on the throttle, making them useless as driver's cars and actually quite dangerous when driven quickly. This applies when coming onto the throttle, and also when coming off it... What about left foot brake spin correction? If things go pear shaped on track and you're going to spin, normally in a RWD car a jab on both pedals recovers even the most perilous situation. Does this mean I can sue Porsche when I spin into a barrier at the ring that I would have otherwise avoided?

Throttle response is awesome in my RS. Can't speak for other models.

Don't use left foot brake spin correction, jump on the ABS and it will sort you out. You can even let go of the wheel and the ABS will stop you spinning and stop any locking etc. The problem with the technique you are espousing is that its hard to pull off if you aren't already left foot braking into the corner, and it requires you to lock up the front wheels to get them to understeer which I don't see ABS letting you do anyway? Works great in a pre-ABS Elise which is the car I was taught it in, but the same instructor suggests not trying to be too clever in a 911 and just using the ABS once you are in deep trouble. I tested this approach on an airfield 2 weeks ago and it definitely works.

[Don]

DanH said:

The drive by wire does let you apply a bit of throttle before cutting power when the brake is applied, but even mk2 GT3s will cut the power after this brief period. I think you can then lift off and reapply the throttle and it will then work, but I've not tried. There is some discussion of this on rennlist and its true for all modern Porsches with drive by wire.

Very interesting. I wasn't aware that GT3's did that. In fact, I thought they weren't equipped with PSM!

I'm pretty sure my 986S doesn't cut throttle under braking - because I once had a over-large-shoe-brake-and accelerator experience where I didn't get the braking I wanted! Luckily I was braking early (for a roundabout, actually) and had plenty of time to reposition my foot so I could brake without accompanying throttle. Needless to say I haven't driven in those shoes again!

I'll have to get the Box out next sunny day and give it a try...

[RobM77]

I will drive one, yes. I have heard wonderful things about them. I do wish people would leave the driver in control though!

[DanH]

Don said:

DanH said: The drive by wire does let you apply a bit of throttle before cutting power when the brake is applied, but even mk2 GT3s will cut the power after this brief period. I think you can then lift off and reapply the throttle and it will then work, but I've not tried. There is some discussion of this on rennlist and its true for all modern Porsches with drive by wire. Very interesting. I wasn't aware that GT3's did that. In fact, I thought they weren't equipped with PSM! I'm pretty sure my 986S doesn't cut throttle under braking - because I once had a over-large-shoe-brake-and accelerator experience where I didn't get the braking I wanted! Luckily I was braking early (for a roundabout, actually) and had plenty of time to reposition my foot so I could brake without accompanying throttle. Needless to say I haven't driven in those shoes again! I'll have to get the Box out next sunny day and give it a try...

It gives you a few seconds at low speed before cutting power.

There is no PSM on GT3s, the nature of ABS means it will save you from a spin if you activate it once you have lost the back end. It does a great job too.

[RobM77]

DanH said:

the nature of ABS means it will save you from a spin if you activate it once you have lost the back end. It does a great job too.

really? How does that work then? surely decelerating is the last thing you want to do in an oversteer situation.

[DanH]

RobM77 said:

DanH said: the nature of ABS means it will save you from a spin if you activate it once you have lost the back end. It does a great job too. really? How does that work then? surely decelerating is the last thing you want to do in an oversteer situation.

It has very good 4 channel ABS. It detects slip on a per wheel basis and moderates braking to each wheel to maximise retardation. A side effect is that it will gather up the back end if its sliding and allow you to steer where you want to go.

It just works

Do some airfield training with a decent instructor if you want to verify, but its also mentioned in the back of Evo this month where the chap has a driving lesson in their 993 C2. John Lyon points out the technique to him.

[RobM77]

cool Sounds good!

I've got plenty of experience on track (5 years of racing, 3 years of track days and some informal instruction), but never in car with ABS...

Maybe one day I'll own a trackable car with ABS and I can try it out!

[paul y]

if you have your foot on the throttle and apply the brake at the same time the ECU will close the thottle after approx 3 seconds.

If you apply the brake first and then the throttle it does not close the butterflys.

Thank our American cousins for this one, stops them driving through the back of their garage when trying to park....

Doesnt stop heel and toe.