bml376

I wanted to see if someone more knowledgeable than me could summarize how the 997 (997.2 if it matters) is suppose to behave when driven on track with PSM on vs PSM off. I do understand that the system can’t really be turned “off”, it is more turning down the threshold before the system will intervene. After some autocross events to get comfortable driving my car closer to its limits with PSM off, I decided to try driving Laguna Seca this past weekend with PSM off. It was a great experience. What I noticed with PSM off was that all of the interventions the system was making when driving the car on track were gone. This was most noticable for me when braking later into turns and trying to trail brake. I just felt like I had much more control of the car. Part of me feels that the car felt safer with the system off vs being on, due to all of the unexpected and automatic interventions being eliminated.

My questions are:

1. When PSM is off, the light on the dash illuminates to indicate that the system is off. However, when driving, I noticed it was sometimes flashing. Does the flashing mean that the system would have intervened had I left PSM on?

2. If the flashing is indicating that PSM would have intervened, should I take that as input on something that I can do to improve my driving? or just ignore it?

Thanks!

924RACR

Pretty sure the flashing light indicates an active intervention (one actually happening).

Note that often, particularly with Porsche, the system will reactivate when on the brake.

Jabs1542

I think it deactivates whenever ABS kicks in, and will stay on until the car is shut down.

dgrobs

Blinking PSM light means PSM is intervening. Maybe what you felt as "you having more control of the car" was actually the PSM taking over for you.
I have felt just that on a few occasions. Unless you are looking at and seeing that blinking light on the gauge, it's very hard to tell whether it is you or the PSM that's actually doing the job.
If it's blinking while you're on track, it is intervening. I believe the above is correct. ABS will trigger it as will threshold braking. I have also seen it intervene in a high speed high G corner as well as when the car compresses, such as the hill crest at speed at LRP or toward the end of the back straight at VIR.
PSM intervenes a lot more than you think it does. If you quickly look down at the gauge once in a while, you'll see how often it can intervene under the right conditions. (note: I am not condoning taking your eyes off the task at hand while at speed).
Good thread. Thanks for starting....

jayzbird

My understanding is with dash switch off it allows a lot more yaw before intervening, and it turns itself on when the brakes are applied (then back off when you let off the brakes). I don’t believe it turns itself back on as if the switch was On when abs engages. Many kill it entirely by pulling the fuse, but I’ve never felt it cramped my style with just the dash switch off, and the
extra safety margin is nice.

924RACR

Agreed - it won't latch on when you touch the brakes, would just be active/available while the brake light switch is activated - which is typically the criteria used by Porsche - others use one or perhaps two wheels in ABS control, and the ones I typically work on won't let it reactivate regardless of brake activity - off is off. Depends on the car, what it wants, as much as the manufacturer...'

I should add, when I say that it can be active while ABS is active - I mean that ESC (PSM) will adjust the modulated brake pressures (asymmetrically) to adjust the vehicle's trajectory in line with teh driver's steering input. So ABS is preventing wheel lock, while ESC is concurrently managing yaw rate.

Kitc2246

I have an 09 Boxster PDK w/Sport/Sport+ from the same era. According to my manual and DE experience when PSM is off it will stabilize when one of the front wheels enters ABS and flash the PSM light indicating an active intervention. Driving on a wet track will quickly show the difference from my experience. If you have Sport/Sport+ and are in one of those modes and PSM is off it requires both front wheels in ABS before intervention.. One-side spinning of the wheels is prevented even with PSM off. From my 16 DE track days PSM is much less intrusive in Sport/Sport+, base on needing both front wheels in ABS to activate. My understanding if PSM is off it will ignore the yaw sensor, but use the yaw input when ABS is engaged as above. Causing PSM to intervene in an "emergency" situation does not turn it back on, just that single event. If you don't have Sport/Sport+ it is available as a software upgrade from Suncoast Porsche or your local Porsche and requires dealer install. IMO it is a must if you have a PDK, not so much with a manual. But as above Sport/Sport+ will make PSM less intrusive.