Retrofit PSM or traction control
Retrofit PSM or traction control
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50something

Original Poster:

48 posts

239 months

Wednesday 2nd July 2014
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Is it possible to retrofit either PSM or traction control to a 04 3.2s 986. I have just purchsed it on condition, owners, mileage and service history\recepits but low on any extras. After a few smoking getaways with a tail wag thrown in for good measure thought it may be a worthwhile upgrade to consider?

edc

9,442 posts

269 months

Wednesday 2nd July 2014
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I thought PSM should be standard on that age of car.

50something

Original Poster:

48 posts

239 months

Wednesday 2nd July 2014
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Well there is no button to indicate that it is fitted or intrusion of it under acceleration, it is a late 04 car, June I think.

VladD

8,128 posts

283 months

Wednesday 2nd July 2014
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This thread implies that TC was on option before 2001, but standard after that.

jkh112

23,540 posts

176 months

Wednesday 2nd July 2014
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The thread implies tc was an option until 2001 and PSM was an option after 2001. It does not imply tc became standard. This is the same as the 996, I think.

50something

Original Poster:

48 posts

239 months

Wednesday 2nd July 2014
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Therefore can either be retrofit at all and if so cost effectively?

jkh112

23,540 posts

176 months

Wednesday 2nd July 2014
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Not cost effective to retrofit.

jkh112

23,540 posts

176 months

Wednesday 2nd July 2014
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Are the tyres up to the job? If you have some cheap rear tyres then switching to ones with a bit more grip would help with the getaways.

Ian_UK1

1,515 posts

212 months

Wednesday 2nd July 2014
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jkh112 said:
The thread implies tc was an option until 2001 and PSM was an option after 2001. It does not imply tc became standard. This is the same as the 996, I think.
My former 996.2 (a Carrera 2) didn't have stability management. From memory, I think it was an option on the C2, but standard on the C4 on facelift cars.

VladD

8,128 posts

283 months

Thursday 3rd July 2014
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jkh112 said:
The thread implies tc was an option until 2001 and PSM was an option after 2001. It does not imply tc became standard. This is the same as the 996, I think.
Well spotted. I really should learn to read all of the words. biggrin

jkh112

23,540 posts

176 months

Thursday 3rd July 2014
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VladD said:
Well spotted. I really should learn to read all of the words. biggrin
You should be out driving, not spending your time on internet forums!

VladD

8,128 posts

283 months

Thursday 3rd July 2014
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jkh112 said:
You should be out driving, not spending your time on internet forums!
If I was retired I would be. At least the internet gives you something to do while you're at work.

boxsey

3,578 posts

228 months

Thursday 3rd July 2014
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Can't say the lack of TC or PSM on my first boxster ever bothered me. It's such a beautifully balanced and communicative car it doesn't need any electronic interference to enjoy it. smile

MogulBoy

3,035 posts

241 months

Thursday 3rd July 2014
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PSM was standard on the 987 but never on the 986. Definitely worth having IMO, although the PSM-EBD is pants in the snow.

Not remotely economic to retrofit.

Your best investment would be to keep it well shod and be careful when rear tread depth is down below 4mm.

Enjoy!

NicD

3,281 posts

275 months

Thursday 3rd July 2014
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I deliberately did not specify TC on my facelift 03 S. Track days are better without it and easy to forget to switch off.
So was an option in the UK.

Nic

MogulBoy

3,035 posts

241 months

Friday 4th July 2014
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Just to add in a bit more about PSM. Some of this is clearly PR talk but a good read.

Porsche Stability Management System
A racer’s perspective
By Jack Miller
Thank you to Jeff Southall of Porsche Cars of North America for the technical information in this article.
April 29, 2001 marked the official return to Formula One of electronic driver aids, including traction control. In racing as elsewhere, technology that enhances (or interferes with, depending on your perspective) human performance is controversial. Potential Porsche buyers face a similar controversy in deciding whether or not to purchase Porsche Stability Management System (PSM) in the new Carrera 2, Boxster, or Boxster S. PSM is standard in the Carrera 4 and Turbo and unavailable in the new GT2.
If you never intend to race your new Porsche, the decision to purchase PSM is simple. If you can afford it, buy it. It provides a level of safety impossible to achieve by driver skill alone. Here’s why. PSM monitors the ABS sensors (which measure the speed of each wheel), engine speed (RPM), throttle position (via E-Gas), gear selection, lateral acceleration (side to side), yaw (the car spinning in a circle), and steering wheel position. This enables the PSM to detect oversteer and understeer. It basically determines the slip angle of the front and rear tires, or more simply, when the car is not going where the steering wheel is pointed. Oversteer is minimized by automatically applying the brake on the outer front wheel in a bend, slowing the rotation of the car; understeer is minimized by applying the brake on the inner rear wheel, speeding the car’s rotation. No driver will be able to do that until Porsche develops a car with four brake pedals. However, PSM is not only a braking system. If you lift off the throttle in a low traction situation (wet, snow, etc.) and the back of the car gets loose, PSM will increase the engine speed (blip the throttle) to keep the car in line. Also, if traction is low, PSM can use engine braking (EDC – engine drag torque control) to slow the car. PSM can calculate the amount of available traction by comparing wheel speeds at all four corners of the car.
Recognizing that even street drivers expect excitement from their Porsches, PSM allows approximately seven percent slip angle before intervening. Five to seven percent is generally agreed to be the limit for modern, high performance tires. The biggest difference between PSM and the other systems on the market today (Mercedes Benz, BMW, Jaguar, etc.) is that PSM is programmed to allow a good deal of slip, as you can see. All of these other systems clamp down the moment any slip (i.e., fun driving) is detected.
However, if you require more fun, you can turn the PSM off. When you "turn it off," you are taking only the outputs offline. The PSM system is still collecting data from the ABS system, the yaw sensor, the lateral acceleration sensors and the steering wheel position sensor. If you have PSM off, and the levels of slip are exceeded, and you do not touch the brakes, the car will continue to slide. If you have not exceeded the levels of slip allowed, and apply the brakes (no matter how hard), PSM will not active its outputs. However, if you have exceeded the levels, AND apply the brakes (no matter how hard), PSM will activate until the car has regained control or you get off the brakes, at which point PSM stops outputting. PSM assumes that since you hit the brakes that you are not comfortable with the level of sliding and that you want it to help. This answers the question, posed by Mike Furnish on the PCASD forum, that inspired this article, "what happens in a spin when you put both feet in?" Presuming that you put in the correct two pedals, PSM will activate.
So what about PSM and racing? At this point in my career, PSM is an asset to my racing. It has allowed me to more confidently explore the limits of traction on the first few laps at a new track, particularly in scarier corners, e.g., Turn 8 at Willow Springs. I was very happy to have it at Phoenix International Raceway, a track with concrete barriers everywhere. When PSM activates you can feel it, much like you can feel ABS. It will show you where you are losing traction while keeping you on the track if the loss was unintentional. When it engages, it may slow you down where you might not want it to later, i.e., where you really do want more oversteer, but on those first few practice laps, who cares? You can actually throttle steer the car quite well with PSM on as long as you are smooth, the yaw is not excessive, and the corner is fast enough to allow smooth inputs. This in itself is a good training tool. So PSM is good for practice, but what about when it matters, during timed laps?
In a time trial situation, it would depend on the course whether it would matter if PSM were on or off. On a tight road course, you would most likely want it off. On an autocross track, you want it off for sure. If you had sufficient presence of mind on a road course you could turn it on and off depending on the corner. You could make sure it’s off for Turn 2 and 4 at Willow Springs, turns where throttle steering comes into play. You could turn it on for Turn 8, the last place on earth you want to see your tail catching up with you. I've never done this, but it illustrates the point.
So far, so good. Since you can turn PSM off, why wouldn’t you want to buy it, even for a car you intend to race? It seems like the best of both worlds. However, remember above where I said that when PSM is off, it is still collecting data and if you hit the brakes when the levels of slip are exceeded, it will intervene. That could be a negative in one racing technique, trail braking, where you are obviously on the brakes and turning. There are two reasons to trail brake, one in which PSM is neutral or even a positive, and one in which it can interfere with the driver’s intention. The first is when you are trail braking to lengthen the straight or to maintain a higher speed through the first part of a turn. In this case, you want the car to stay on its directed path. If things are going as intended, PSM is very unlikely to engage even though you are on the brakes. If it does, it is probably because you lost rear traction in a pretty big way. By engaging it didn’t cost you time since your intention was to slow down anyway and it may have saved you from spinning. The second use of trail braking serves a different purpose. If you are trail braking to induce some oversteer intentionally to tighten the corner, PSM could interfere in the same way as when it is on and you lift to oversteer. While I have a lot of experience throttle steering the car, with PSM on and off, I don’t brake to loosen the rear of my 996 C2. Lifting is normally sufficient. However, I have seen this technique, in the form of left-foot braking, used in a friend’s 993 C4 in Turn 4 at Willow and Turn 5b at Spring Mountain and presume it would be useful in the newer 996 C4. Since the 993 does not have PSM, I cannot tell you to what extent it would have interfered. If you are smooth, probably very little, if at all. But, this is one possible negative to weigh against the aforementioned positives. I think it’s worth it, but let me give the last word to Porsche.
"We wanted the car to perform like a Porsche not a family saloon, so the system has been designed for minimal intrusion," explained Thomas Herold, the Carrera 4 Project Manager. "Its limits are really high and you can reach the same lateral g-force number with the system in or out on a steady state cornering circle. Thus, if you are a good driver, you can keep the power on in a drift and even adjust the car’s attitude on power in a corner without interference. But if you lift off suddenly or brake, and the car is in danger of destabilizing, the system will reach out and save you."
"The difference is small around the Nurburgring for a skilled test driver," he explained. "Within one second a lap in fact. This is the way the car is made. If you are smooth, there is no interference from the system. But if you are ragged, the system will be cutting in all the time to stabilize the car, so an aggressive driver will be slower with the system on."

thegoose

8,075 posts

228 months

Friday 4th July 2014
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PSM was only available on e-gas cars (electronic throttle instead of cable) and is the same AFAIK as ESP on VW/Audi cars, and is considered such a contribution to safety that it's going to be mandatory on all new cars (I think it already is for new-to-market cars and soon will be for everything, regardless of when it was launched).

Such a system is most effective where it can activate any combination of power or braking to all four wheels i.e. on a 4WD car, and will do its best on a 2WD car. By comparison, traction control will just limit the power to the driven wheels to prevent wheelspin.

However, for a Boxster with decent tyres there's very little chance of it ever coming to use in the dry unless it really is an emergency situation (high speed swerve to avoid something which, without PSM, would definitely cause a spin, and with it might be avoided).

If you still feel you must have a control system of some kind then there are aftermarket solutions available. I once had an E36 M3 that had a Racelogic traction control system fitted, complete with a little box with a knob to vary the degree to which it operated/interfered. I turned it off as it was more fun without it drivingbiggrin