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01-15-2009, 03:43 PM
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PSM (not PASM)
Although many threads deal with PASM, I don't believe any have given a good description of the components of PSM and how it works. The Porsche website is noticeably lacking in this regard as well. How does PSM work? Is any type of slip differential involved?
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PASM - Porsche Active Suspension Management
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This active damping system offers continuous adjustment of individual damping forces based on current road conditions and driving style.
The driver can choose from two setup modes, ‘Normal’ and ‘Sport’, using a separate ‘damper’ button on the center console. ‘Normal’ mode is designed for general road driving and circuits with uneven tarmac. ‘Sport’ mode is intended for smoother track surfaces, where the harder settings help eliminate pitch and roll.
In either mode, PASM continuously evaluates the current conditions while automatically selecting the corresponding damper rates from the respective set of mapped values.
A range of sensors are used to monitor the movement of the body under acceleration, braking and cornering maneuvers, as well as on poor road surfaces. The PASM control unit then evaluates this data and modifies the damping force on each individual wheel in accordance with the selected mode. The result is a significant reduction in body movement as well as a better grip on the road.
For example: if ‘Sport’ mode is selected, the suspension is automatically set to a harder damper rating. If the quality of the track surface falls below a certain threshold, the system immediately changes to a softer rating within the ‘Sport’ setup range. When the quality of the tarmac improves once more, PASM automatically returns to the original, harder rating.
Need more information about PASM? Click this link: FAQ for PASM |
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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01-15-2009, 04:02 PM
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Geek
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Re: PSM (not PASM)
Download this The Cayman Club - Downloads - AfterSales Training - Suspension, Brakes & Alignme and read the sections about PSM. There is a LOT of excellent information! Read chapter 4 in its entirety. It describes many older PSM systems, but it's important to understand those earlier systems to best understand the current system. 
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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01-15-2009, 04:05 PM
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Moderator & 11 Year PCA Member
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Re: PSM (not PASM)
Some years back, when PSM was introduced, Panarama had a spectacular article that fully explained the operation. Aside from that the literature I have seen since is fairly less comprehensive.
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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__________________
*******************************
The search tool is your friend. It is very
likely that your question has already been
answered countless times.Very,very likely.
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Cayman S - a portable amusement park 
- 2006 Cayman S
- 2003 Dakota SXT
- 1963 Studebaker Avanti, R2, 4-Speed
*******************************
LL
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01-15-2009, 06:45 PM
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Site Donor
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Re: PSM (not PASM)
Thank you.
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01-30-2009, 10:01 AM
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Re: PSM (not PASM)
Alot of information there and I'm not capable of digesting all of it, however, it seems the autiomatic brake differential is a form of LSD. NO?
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LSD - Limited Slip Differential
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A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.
The main advantage of a limited slip differential is found by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely– the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels.
To see the installation of a LSD style unit Click Here -> Article Forthcoming Stay Tuned |
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01-30-2009, 10:13 AM
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Moderator & 11 Year PCA Member
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Join Date: Jan 2006
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Re: PSM (not PASM)
No.
LSD's point is to ensure that you retain traction. With the differential you have now, you can get wheel spin (loss of traction) coming out of hard right turns, as the inside wheel can't handle all the load. If the outside wheel is also used for "drive" then this loss is minimized to the maximum possible.
What PSM does is to apply the brake to avoid loss of control, by correcting steering. And while is isn't the same, it may have a similar effect. Some folks have reported better track times with PSM on than with it off. But, I haven't heard of anyone reporting PSM being better than an LSD.
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LSD - Limited Slip Differential
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A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.
The main advantage of a limited slip differential is found by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely– the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels.
To see the installation of a LSD style unit Click Here -> Article Forthcoming Stay Tuned |
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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__________________
*******************************
The search tool is your friend. It is very
likely that your question has already been
answered countless times.Very,very likely.
*******************************
*******************************
Cayman S - a portable amusement park
- 2006 Cayman S
- 2003 Dakota SXT
- 1963 Studebaker Avanti, R2, 4-Speed
*******************************
LL
Last edited by fmarshall; 01-30-2009 at 10:35 AM.
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01-30-2009, 01:26 PM
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Site Donor
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Join Date: Jun 2008
Location: NY
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Re: PSM (not PASM)
Thank you, fmarshall.
Would you say then that PSM obviates the need for LSD if the vehicle is used for daily driving only?
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LSD - Limited Slip Differential
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A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.
The main advantage of a limited slip differential is found by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely– the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels.
To see the installation of a LSD style unit Click Here -> Article Forthcoming Stay Tuned |
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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01-30-2009, 03:14 PM
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Porsche Spieler
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Re: PSM (not PASM)
Originally Posted by SGF
Alot of information there and I'm not capable of digesting all of it, however, it seems the autiomatic brake differential is a form of LSD. NO?
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I actually thought the exact same thing. It made me thinking, if that's an LSD imitation, then it must be a real blast driving an LSD equipped car!
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01-30-2009, 03:57 PM
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Re: PSM (not PASM)
Originally Posted by SGF
Thank you, fmarshall.
Would you say then that PSM obviates the need for LSD if the vehicle is used for daily driving only?
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Not at all. IMO a Quaife ATB/ LSD is highly beneficial for street driving. Since new, my '06 CS has been 90-95% year 'round daily driver and 5-10% track car in advanced/instructor groups. Wheelspin on the track has not been a major issue. However, getting up hills/driveways in the snow (even with my winter tires) has. PSM/TC helped, but not much, and certainly not enough.
I recently installed a Quaife & it's made a huge difference in improved handling, stability and driveability in wet/slippery conditions. I can easily drive up hills/driveways that were impossible before the Quaife. There's a noticeable improvement in the rain. If you'd like a more stable, sure footed car, you'd like a Quaife/ LSD.
PSM is designed to (hopefully) save you after you're in trouble, while ATB/ LSD will keep you from getting into trouble. Although having PSM is comforting to have, I don't ever rely on it to save me. I generally turn it off for the track. Even if I could, I can't think of a circumstance I'd turn off the Quaife.
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LSD - Limited Slip Differential
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A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.
The main advantage of a limited slip differential is found by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely– the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels.
To see the installation of a LSD style unit Click Here -> Article Forthcoming Stay Tuned |
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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__________________
Dan
Last edited by STLPCA; 01-30-2009 at 04:06 PM.
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02-01-2009, 10:44 AM
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Porsche Enthusiast
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Join Date: Nov 2008
Location: TX
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Re: PSM (not PASM)
I really don't like the fact that the car thinks and reacts for me now that I've had it for a couple of months. I know when the rear will go out and when it will stay put (i.e., I know how much throttle I'm using). Yesterday, after watching the PSM light trigger as I went around a corner and slowign me down at the same time, I tried the PSM in off. I really like the extra control I can give the car. So, is there a way to reverse the way the switch works--when you start the car, PSM is off, and when you push the button, PSM is on?
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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02-02-2009, 01:51 PM
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Moderator & 11 Year PCA Member
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Join Date: Jan 2006
Location: CA
Posts: 2,482
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Re: PSM (not PASM)
It would seem to be pretty easy to reach over and push a button. Forgetting to do so, for those folks that need PSM on, wouldn't be safe from Porsche's point of view, IMO.
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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__________________
*******************************
The search tool is your friend. It is very
likely that your question has already been
answered countless times.Very,very likely.
*******************************
*******************************
Cayman S - a portable amusement park
- 2006 Cayman S
- 2003 Dakota SXT
- 1963 Studebaker Avanti, R2, 4-Speed
*******************************
LL
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02-02-2009, 01:54 PM
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Moderator & 11 Year PCA Member
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Join Date: Jan 2006
Location: CA
Posts: 2,482
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Re: PSM (not PASM)
Originally Posted by SGF
Thank you, fmarshall.
Would you say then that PSM obviates the need for LSD if the vehicle is used for daily driving only?
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Unless you drive in rain and snow like STLPCA does. 
I live in CA, and it works just fine for me.
__________________
*******************************
The search tool is your friend. It is very
likely that your question has already been
answered countless times.Very,very likely.
*******************************
*******************************
Cayman S - a portable amusement park
- 2006 Cayman S
- 2003 Dakota SXT
- 1963 Studebaker Avanti, R2, 4-Speed
*******************************
LL
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02-02-2009, 03:21 PM
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Porsche Enthusiast
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Join Date: Nov 2008
Location: TX
Posts: 108
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Re: PSM (not PASM)
Originally Posted by fmarshall
It would seem to be pretty easy to reach over and push a button. Forgetting to do so, for those folks that need PSM on, wouldn't be safe from Porsche's point of view, IMO.
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It is, but, I really don't like the big yellow light. I would rather turn it on when I wanted and leave it off the majority of the time.
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02-02-2009, 03:42 PM
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Porsche Purist
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Re: PSM (not PASM)
I was playing with my car a bit. I stopped with one rear wheel on asphalt, and one on dirt. (Well, dirt covered asphalt.) And then turned off PSM and proceeded with a burnout. PSM (or ASR) kicked in anyway. Light was flashing on the dash, and the car accelerated more or less without fish tailing.
From manual:
One-sided spinning of the wheels is reduced,
even with PSM switched off, to enable optimum
traction on all drive wheels.
Wonder how this would work with ATB fitted. I guess more testing later.
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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__________________
Tomasz
Apologies for spelling mistakes, most of them are keyboarding errors. To enjoy this forum I run out of time to proof read.
My garage: 2000 Audi S4 (not stock) | 2007 Porsche Cayman S (FabSpeed Headers, RS60 Tips, SRP 4.1, ATB, GT3 Ducts, GT3 RS Steering & Shifter, Custom Aluminum Look, ZR4)
Last edited by Tomasz; 02-02-2009 at 03:50 PM.
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02-03-2009, 10:00 AM
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Porsche Chatter
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Join Date: Nov 2008
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Re: PSM (not PASM)
Originally Posted by dougc
I really don't like the fact that the car thinks and reacts for me now that I've had it for a couple of months. I know when the rear will go out and when it will stay put (i.e., I know how much throttle I'm using).
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Probably when speeding on a controlled environment that might apply, but when you are on an non fully controlled environment PSM is by far the best addition to the new Porsches (and cars in general)
The previous weekend I went to my local track to do some speed tests, (its a 10km twisty track) and in a corner with good visibility I wanted to test how the car handles when going at full acceleration, not during the corner, but accelerating in the staright and entering the corner with the pedal pressed to mantain the acceleration during it, I entered the corner at 150kph and mantained the acceleration over the complete turn, but just after the middle of it the tail started to drift (the tires were not warm enough) for me it was a totally different feeling with the mid engine car, it was as if the pivot it is on the middle of the car (I am very used to controlling front engine rear wheel drive cars on corners, even when drifting), I just lifted the pedal to move the weight distribution to the front and induce oversteer, but the car already was in a spin, I was looking directly at the side of the road (there is a lake there) the car was transversely on the road, and with a tight corner right next, to the opossite side, where there is a big wall on a side and the mountain on the other. I was only thinking about how to stop the car the in the most safely possible way but suddenly the yellow dash light come on and in less than a second, with a very abrupt intervention of the PSM the car is on the correct line again, totally controlled, in the entrance of the next corner, ready to push the throttle again
There is no way that any human can control a car better than a computer (just think that in a second the car computer can know 1 million times how much the flywheel has moved), what a human can do is to avoid the dangerous situtations, but by far the computer can handle them better than anything (similar as why today the most advanced combat airplanes can't fly without the electronic system that stabilizes them)
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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02-03-2009, 10:30 AM
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Moderator & 11 Year PCA Member
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Join Date: Jan 2006
Location: CA
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Re: PSM (not PASM)
So I want to have a body kit that makes my car as ugly as a stealth fighter. That way I can drive as fast as I want without being caught by radar!!
__________________
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The search tool is your friend. It is very
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answered countless times.Very,very likely.
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Cayman S - a portable amusement park
- 2006 Cayman S
- 2003 Dakota SXT
- 1963 Studebaker Avanti, R2, 4-Speed
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02-03-2009, 12:50 PM
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Porsche Spieler
2,000 post club
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Join Date: Dec 2007
Posts: 2,208
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Re: PSM (not PASM)
Originally Posted by zmRoadster
Probably when speeding on a controlled environment that might apply, but when you are on an non fully controlled environment PSM is by far the best addition to the new Porsches (and cars in general)
The previous weekend I went to my local track to do some speed tests, (its a 10km twisty track) and in a corner with good visibility I wanted to test how the car handles when going at full acceleration, not during the corner, but accelerating in the staright and entering the corner with the pedal pressed to mantain the acceleration during it, I entered the corner at 150kph and mantained the acceleration over the complete turn, but just after the middle of it the tail started to drift (the tires were not warm enough) for me it was a totally different feeling with the mid engine car, it was as if the pivot it is on the middle of the car (I am very used to controlling front engine rear wheel drive cars on corners, even when drifting), I just lifted the pedal to move the weight distribution to the front and induce oversteer, but the car already was in a spin, I was looking directly at the side of the road (there is a lake there) the car was transversely on the road, and with a tight corner right next, to the opossite side, where there is a big wall on a side and the mountain on the other. I was only thinking about how to stop the car the in the most safely possible way but suddenly the yellow dash light come on and in less than a second, with a very abrupt intervention of the PSM the car is on the correct line again, totally controlled, in the entrance of the next corner, ready to push the throttle again
There is no way that any human can control a car better than a computer (just think that in a second the car computer can know 1 million times how much the flywheel has moved), what a human can do is to avoid the dangerous situtations, but by far the computer can handle them better than anything (similar as why today the most advanced combat airplanes can't fly without the electronic system that stabilizes them) |
I gotta tell you, you do know how to tell a story. I felt as if I'm actually watching you 
But how exactly did it spin? I assume it oversteered right? If that's the case why did you try to induce more oversteer? And did the car really spin 90 degrees (if I understand correctly) with PSM on? 
P.S. I'm not challenging your story, I'm actually interested in understanding more!
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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__________________
"Sir! We're surrounded!" - "Excellent! We can shoot in any direction!"
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02-03-2009, 02:52 PM
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Porsche Enthusiast
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Join Date: Nov 2008
Location: TX
Posts: 108
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Re: PSM (not PASM)
Great story!
I'll just do what a fighter pilot told me to do--put tape over it.
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03-04-2009, 07:05 PM
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Zone 1 Member
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Join Date: Apr 2008
Location: CT
Posts: 25
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Re: PSM (not PASM)
I had a recent experience with PSM while driving up a steep snow covered hill. The car ahead of me slowed to the point that I was forced to stop. When I tried to start again the tires slipped and the PSM kicked in and reduced the throttle response to almost nothing. My foot was on the floor and the car was barely moving forward. Of course there were cars behind me so I let the car work out thing for itself rather than experiment. A couple of questions occurred to me:
1. Would letting off the gas and then stepping on it again change the way it was behaving? Sort of like pumping the gas pedal. I tried this later on an open hill and it seamed to help some but I'm still not sure.
2. What would have happened if I reached down and turned off PSM during this? Would the engine have imediately gone to full throttle sine I had the pedal to the floor?
In this condition I would have preferred the LSD in my previous 944T to the PSM. In the same condition I could have applied gas and the snow tires would have cleared the snow out of the way.
Anyone have thoughts on how to deal with this the next time (hopefully next winter)?
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LSD - Limited Slip Differential
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A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.
The main advantage of a limited slip differential is found by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely– the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels.
To see the installation of a LSD style unit Click Here -> Article Forthcoming Stay Tuned |
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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10-30-2009, 11:05 AM
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Porsche Chatter
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Join Date: Sep 2009
Location: SC
Posts: 44
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Re: PSM (not PASM)
Was PSM standard on all 2006-2008 CSs? From my thread search and car manual reading I would assume so, want to confirm. Thank you.
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PSM - Porsche Stability Management
|
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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