I turned PSM off last weekend and wow what a difference. my question - is it still worthwhile to press that "sport" button when PSM is off? I couldn't tell if "sport" adds anything when PSM is off. 2009 CS

 

confused on why no one respodned to this pretty good question

 

Try it, sport button maps the throttle to a lighter mode. PSM keeps the gears longer adn wont shift automatically if redlined.

 

The sport button should still stiffen up the suspension (assuming airbags) and change the throttle input, shift maps, etc.

 

Sport Button on a Cayenne does NOT re-map the throttle (as it does in other models); however, it does stiffen up the suspension. PSM turns off all stability control safety features and robs a lot of HP.

 

How does the PSM "rob HP"?


The one big differnece you will notice is that when you turn off the PSM the Cayenne will always start out in 1st gear. With the PSM on it will automatically start in 2nd gear all the time. This is going to be the biggest difference.

You can manually select first gear with the buttons on the steering wheel without putting it in manual mode. Just click down on the button when you roll up to a traffic light and it will now start in 1st and still have PSM on.

 

"How" it robs HP techically I do not know. PSM and AC both diminish available power. Simply tyring different settings and take offs and it becomes readily apparent (admittedly seat-of-the pants) that those features take a lot of HP.

 

A/C is a mechanical pump being driven directly off the crankshaft of the car and has a "parasitic loss" associated with it. It simply takes HP to drive the pump. Usually 10-15ish hp. Many modern cars are cycling the A/C compressor all the time weather you have the A/c on or not. Not sure I could feel the differnece on my CTT, but on my 86 951 turning on the A/C is like throwing an anchor out the window.

PSM is an electronic system that should only interfer when wheel slip is detected. If you accelerate hard enough to spin the tires the PSM will simply pull back throttle to let the tires grip and maximize acceleration on the slick surface. Its' not limiting HP. You should actually accelerate faster wtih the PSM on than with it off. It will just *feel* and *sound* faster with the wheels squealing and the back end sliding around.

Now, it you want to spin the tires, drift, etc. Then, yes, the PSM will take away the power you need to do so and should be shut off.

Keep in mind that Stability Management systems on modern cars can do things you don't even have the controls in the vehicle to do. For example, they can sense yaw and brake just one wheel to prevent a spin/slide. Not as much fun, but certainly safer. This in no way should be an excuse to not learn the skills to control a car in a slide. It should be a great backup to your own skill.

 

My autocross instructor insisted I turn PSM off.

During winter driving when I expected to slide (purposely as I am quite skilled at winter driving) PSM would interupt my driving flow so much that it was rude & embarassing.

HOWEVER, on the Alcan at speed PSM saved my *** on many ocassions, especially appreciated the system working to keep me and that dirty ice cube of an overloaded trailer on an icy road (Top Dead Center Speedometer ;-) ) when i blew a tire out on the trailer. Fact is, I was about the only car towing that stayed on the road druing the first winter strom on the Alcan. Also, it saved my *** when I was about to T-bone a 40-wheeler.

Driving skills need to be developed under all conditions for all conditions.

My CTT has four climate zones and I need to figure out how to turn the back seats A/C off to save gas. Tme for the manual--unless someone here can explain it easily to me.

 

This has nothing to do with "power". The goal of an AutoX is to drive at the limit without going over it. So pushing the car to the 100% mark without goint to 101%. Stability programs will typically start to step in early than the actual limit, say 90-95%. They try to use the remaining 5-10% to save you from the limit. This all means that the PSM would be stepping in too early to have a fast autoX run. The same is happening to you in the snow if you are trying to slide the car around.

4 zone or 2 zone does not make a difference, there is only 1 A/C compressor on the engine.

 

On the CTT the traction controls kick in way too early (but I drive with them on). And they come in HARD. I wish the PSM came in gradually and step-wise like I imagine it does on the Cayman and 911.

Actually, the way PSM woks on the CTT, it steps in far under 90%. As I get more experience I'll have a firmer percentage but right now it seems close to 80% or even 65%!!!

 

On my 05 S I drive with the PCM off all the time accept on long highway trips. With PSM off and my sprintbooster installed, my c leaps off the line and between 2500 - 5000 rpm has very tight throttle control. PCM on has almost killed me a few times as there is large dead-zone in the pedal (even with the sprint booster) which does not work so well when you are slow rolling through a left hand intersection turn. If I could find someone to make me a foil overlay that says "FUN" instead of "PCM" I would gladly install it.

 

roxboxxx, I find that in left hand turn situtions in which I need to clear an intersection or speed up my entry into the roadway my CTT often cathces me by surprise. All four tires dig in and she takes off almost emabrassingly fast.

 

Lol - happens to me also sometimes when psm is off. Just a tad to far and you look like u are just learning how to drive a manual. I don't dare drive barefoot around town. In this instance it's more like PMS then PSM.

 

I don't understand why my CTT becomes such a beast during those broad left hand turns, yet won't lay it down nearly as much on right hand turns. Of course, they are generally tighter.