Pugnacious P

I was wondering what the difference is between the traction control on mine with the later PSM. It seemed a little vague in the book and I'm a little dense

gota911

Sorry, I can't help you because I have no experience with the '99 traction contorl, nor do I have experience with PSM, because my '04 does not have PSM.

However, I wanted to let you know that anyone that can poke a little fun at themself is A-OK in my book!

newport996

Traction control uses just the brakes to control the car when it senses a loss of traction, PSM uses more sensors and also uses the throttle, which is why you needed e-gas for this.....PSM is a better option....

lowside67

Err, traction control includes a limited slip differential and can be turned off completely... i'll take t/c over psm anyday thanks.

newport996

HMMMM.....Well from what i can tell from my Boxster with TC and my PP6 with PSM, PSM works MUCH better than TC, and I have never heard of someone preferring the older technology of TC over the newer PSM. And I usually hear that one WANTS PSM on any 996 they get, UNLESS you are strictly tracking it.

GreigM

TC and PSM have nothing to do with a limited slip diff -this was a separate option.

TC - used the theory of progressive injector cuts to effectively "ease off" the gas electronically - it has no control over brakes so can only help wheelspin and power oversteer - can't help understeer or lift-off oversteer.

PSM - includes TC but also has the ability to independently apply each of the 4 brakes, by doing this it can deal with lift-off oversteer and can correct braking instability problems

Ray S

Bzzzz......wrong answer. TC does not include LSD.

Eli K

Ray, every car I've seen with TC did in fact include LSD as an option. Just check under the hood, the code is 220.

smackboy1

Fear not, as with all the most important questions in life, the answer can be found on the telly:

This is a snippet from 5th Gear with Tiff in the arctic circle where he tests ABS, traction control and electronic stability program (ESP), the generic term for PSM.

http://racingflix.com/getvideo.asp?v=1090

(you have to register to download but it's free)

aben8057

That is why Porsche now has PSM as an option not TC....

JimB

I would look at this a little differently. Traction control is a performance enhancement. Limited slip is a performance enhancement. Either together or as separate options they work to keep your rear tires at maximum adhesion. Traction control does it by limiting power output to the maximum that will not spin the wheels. Limited slip does it by shifting power between rear tires or applying power to both. So many F1 teams were cheating by adding traction control a few years ago that they finally made it legal. That's why they can just mash the pedal coming out of corners and not get wheel spin. The computer limits the power being applied rather than having the driver do it. Same thing on starts.

Every Porsche should come standard with LSD. Traction control should be an option and should come with a defeat switch.

PSM is a safety device, not a performance enhancement. It's there to save your butt when you get in over your head. I suppose that is a good thing but I really don't think it belongs on a sports car. I think we need to respect these cars and learn to handle them the way you learn to ride a spirited horse. I guess those days are long gone.

Just my opinion,
Jim

newport996

Jim, I would have agreed with you except the 2 times my PSM has kickied in it saved me and I was not driving over my head....One road was a sudden patch of mud in the apex of an otherwise dry road. ALL 4 tires suddenly lost grip and the car went into a spin, before I knew what was happening, the PSM kicked in a righted the car. Without PSM, I am sure I would have ended up in the guard rail. I was doing about 30mph. In my opinion with the HP of modern cars going higher and higher, these safety features are a GREAT option. I am not worried about my wife driving a 300HP car in the wet because of AWD and PSM. My 200 HP Boxster without PSM was a pain in the *** when the roads were wet.....I'd spin the tires leaving stop lights. Very easy to do. Again, for SERIOUS tracking and the proper driver, no need, for everyday driving, you wont notice it UNTIL you need it, then you will be glad its there.

wwest

First, my 99 had traction control and I'm quite sure it would brake the rear wheels, and dethottle the engine (via fuel starvation?) with wheelspin. I'm also quite sure it would use differential braking at the rear to simulate, virtualize, an LSD. So yes, any 996 with traction control had an "LSD".

My 2001 AWD has PSM which is a unique stability control system in that it delays activation for a few hundred miliseconds to allow the driver time to react correctly. PSM includes the above traction capability plus it uses a yaw sensor (lateral accelerometer) and a stearing wheel position sensor to determine that the vehicle is NOT following the desired "line".

In three HOT laps at Daytona PSM did not even activate once. But keep in mind that I was in a position wherein I was constantly "on my toes", fully prepared to sense an out of whack situation and react correctly.

We cannot, will not, be constantly alert and so that makes PSM a very highly desireable option, especially as implemented by Porsche.

lowside67

Maybe this is not the case on the 986, but all the 996s that had TC had LSD, and no n/a 996 except the 40th and the gt3 had an LSD after that.

In a perfect world, I'd like to have PSM (yes I said it), an LSD, and a big "off" button that can defeat all the electronic aids if I so choose to. However, as I understand it, PSM and an LSD are mutually exclusive given current technology, and PSM is not 100% defeatable. Thus, I choose T/C over PSM while acknowledging neither are the perfect solution.

Robin 993DX

To answer the original question:

I don't think there are any difference with the PSM from 99 and newer model.


Now for the PSM and traction control discussion:

FWIW, this is from my understanding.

C2 (coupe, cab or targa) - optional PSM or LSD
C4 (coupe, cab) - Standard PSM optional LSD
Turbo - Standard PSM optional LSD

I was not aware that Porsche had a separate traction control package besides the PSM. The PSM can be categorized as the traction control device, but performs a lot better than your garden variety traction control that are now standard on my cars over $30k.

What really sets the PSM different is the software programming and the array of sensors that it uses. The system reacts extremely fast like most traction controls, but in the same time it also turns off very fast. Imagine it to turn on for a brief second and turns off again, and turn can turn on right away if it sense something is wrong.

In layman's term, the Porsche PSM system is designed for a sports jockey, where the tolerance level is higher before it kicks in, it allows some wheel spin, and it lets you get back to whatever fun you were having before it steps in too much.

This is evident when I drive my 3 series BMW with traction control, the second any one of the wheels breaks loose the traction light turns on and you can feel lost of power (e-gas) and the brake calipers working to keep all 4 wheels in sync, the duration is very long and really hinders the performance.

In my C4 with PSM, I rarely get the PSM light to fire off, even if it does, it is just for a split second and turns off right away and I never felt any power lost as I did with the BMW, even thought supposely it does manipulate the throttle (only to back off not on). Even in a raining weather on a full throttle take off with some wheel slip, the PSM will not turn on at all. Like it knows, that's what I intentionally wanted to do. But now if I put the car in a 4 wheel drift on a dirt road even at a slow 10 mph speed the PSM fires off right away to keep the car in control (Very ironic, a controlled out of control).

Just for fun I started to experiment on dirt roads just to see how well the PSM works. To my amazement I found myself doing the perfect 4 wheel drift slide park consistently .... whatever you call it.

I think the PSM with the 4 wheel drive system is the perfect performance combination for spirited street driving, as the road surface changes so randomly and there are always the unexpected. But I can see how the PSM can ruin a fun experience in a familiar track environment, luckily there is always the off button, but unfortunately it can't be turned off permanently, as it always wants to keep a watchful eye on what you are doing.