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YOUR RESEARCHPSM - has it changed over the 996 years?
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Replace '02 it
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Carreras with PSM's work evolved similarily, first C4's got PSM '99 and that 1st gen unit/sensor set was used until '01.
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Suggestion
The programming is the same, or at least if you replace malfunctioning '02 unit with '04 unit it's just told if it's in tiptronic or manual car.
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I did a google search (and one here as well) regarding PSM. I couldn't really find an answer to my questions. Is the PSM system on a 1999 996 the same as the one in my 04 40th Anniversary? Does the LSD help the system in any way? Last question is does it help with the lift off throttle oversteer issue?
Here is a description from Porsche's website:
PSM, which comes as standard, is an automatic control system that stabilises the vehicle at the limits of dynamic driving performance. Sensors continuously monitor driving direction, speed, yaw velocity and lateral acceleration. Using this information, PSM computes the actual direction of motion. If this direction deviates from the desired course, PSM initiates braking interventions targeted at individual wheels in order to stabilise the vehicle.
Under acceleration on wet or low-grip road surfaces, PSM improves traction using the ABD (automatic brake differential) and ASR (anti-slip regulation) functions, giving an agile response. When ‘Sport’ mode is selected on the optional Sport Chrono Packages, the PSM intervention threshold is raised to enable greater driver involvement – particularly at speeds of up to approximately 70 km/h (45 mph). The integral ABS can further reduce the braking distance.
For an even sportier drive, PSM can be deactivated. However, it is automatically reactivated for your safety if either of the front wheels (in ‘Sport’ mode, both of the front wheels) requires ABS assistance. ABD remains permanently active.
PSM has been enhanced and now includes two additional functions: precharging of the brake system, and brake assist. If you suddenly release the accelerator pedal, PSM automatically readies the braking system. With the braking system having been precharged, the brake pads are already in light contact with the brake discs. Maximum braking power is therefore achieved much sooner. When sudden braking is detected, the brake assist function applies maximum brake pressure to all four wheels.
Thanks,
Steve
Quote from my answer to question how PSM's have evolved:
First turbos used different Drehratensensor ie. "Yaw angle" sensor, which only communicates with certain ABS/PSM unit. Bosch brought a new sensor to MY '02 and works with all ABS/PSM units since. The programming is the same, or at least if you replace malfunctioning '02 unit with '04 unit it's just told if it's in tiptronic or manual car. Wiring looms are identical.
Carreras with PSM's work evolved similarily, first C4's got PSM '99 and that 1st gen unit/sensor set was used until '01. '02 it was replaced with 2nd gen.
And there's one more thing, 2WD Motronic requires a 2WD PSM unit and 4WD Motronic a 4WD unit.
I'm using a 4WD turbo PSM in 2WD car, and at least the winter went well, had fun...
Even more PSM disconnected.
And the transmission has a Cup car LSD. Track season is starting, so more comments about that later.
Following is based to my own observations: LSD helps the PSM. If accelerating without yaw there's no throttle cut-off although both rear wheels are slipping ( because of no rear wheel speed difference ). If the rear starts to move ( well, it requires more than just a sight yaw ) sideways there will be a PSM intervention. NOTE: This applies to part throttle acceleration. Full throttle pull from traffic lights causes quite immediate PSM intervention. Although this might have something to do with 500+ hp...
Lift-off oversteer will be intervened immediately if the PSM is on. If it's off, only after you hit the brakes. LSD enhances lift-off oversteer.
PSM saved my bacon last week on the day we got 3 inches of rain in less than 24 hours. I was coming out of a left-hander and accelerating hard on an I5 on ramp and suddenly found myself on an oil slick and going sideways. Oops. I steered into it and kept my foot steady and felt the PSM kick in just before I would have contacted the wall. I have never been a fan of PSM, but it was certainly helpful here. In my 993, with just LSD/ABD, I am pretty sure that I would have hit the wall.
