2013 911 SCab - new rear tires, lost PSM
08-10-2021, 08:50 PM
#1
Intermediate
Thread Starter
2013 911 SCab - new rear tires, lost PSM
I installed new rear Continental tires on my 2013 911 SCab (2 wheel drive), with 66k miles. The new tires are the same size as the old tires. Everything seemed ok until I hit one of my favorite routes with some hills & tight curves. I'm usually able to take them at 50 mph +/-, with no issues.
However, 10 days ago, with the new tires, the PSM (Porsche Stability Management) system started blinking, and seemed to fail. The blinking is an on/off yellow image of the car next to the tach, with S skid marks behind rear wheels. I'm the 2nd owner, and have had the car for 4 years, never before has this light come on. And, the rear end was unstable. It felt like a 200# dead weight was in the back, shifting from side to side, creating instability in taking the corners. On the straight away, the car drove fine. But it's the curves that make this car fun, right?
The PSM is "an active control system for stabilization for the vehicle during extreme driving maneuvers. PSM makes use of both the automatic brake differential and anti slip regulation systems, as well as the functions of the anti lock brake system and engine drag torque control system." More simply put, the PSM allows the driver to corner at higher speeds with no loss of control
I called Steve DeJung, at DeJung Motorsports in Cotati CA. He said it sounded like the PSM was switching off, leading to the instability. I'm taking the car back to Wheel Works in Santa Rosa, where I got the new tires. When I made the appt, they said their machine calibrating the tire weights had been recalibrated a few days ago, after another customer had an issue. They'll redo the weights, and align the wheels.
Are there any ideas of what is evidently causing the PSM to switch off?
Could it be the wrong weights were used, or the wheels are out of alignment?
However, 10 days ago, with the new tires, the PSM (Porsche Stability Management) system started blinking, and seemed to fail. The blinking is an on/off yellow image of the car next to the tach, with S skid marks behind rear wheels. I'm the 2nd owner, and have had the car for 4 years, never before has this light come on. And, the rear end was unstable. It felt like a 200# dead weight was in the back, shifting from side to side, creating instability in taking the corners. On the straight away, the car drove fine. But it's the curves that make this car fun, right?
The PSM is "an active control system for stabilization for the vehicle during extreme driving maneuvers. PSM makes use of both the automatic brake differential and anti slip regulation systems, as well as the functions of the anti lock brake system and engine drag torque control system." More simply put, the PSM allows the driver to corner at higher speeds with no loss of control
I called Steve DeJung, at DeJung Motorsports in Cotati CA. He said it sounded like the PSM was switching off, leading to the instability. I'm taking the car back to Wheel Works in Santa Rosa, where I got the new tires. When I made the appt, they said their machine calibrating the tire weights had been recalibrated a few days ago, after another customer had an issue. They'll redo the weights, and align the wheels.
Are there any ideas of what is evidently causing the PSM to switch off?
Could it be the wrong weights were used, or the wheels are out of alignment?
Last edited by Tomasphil; 08-10-2021 at 09:03 PM.
08-10-2021, 10:15 PM
#3
Intermediate
Thread Starter
rear tires are at 45 #, the recommended level. The road was dry, a sunny day at 70 degrees. Perfect conditions.
The reason I say PSM was off was the car was hard to control, and it was like a 200# lead weight was in back, shifting from side to side. It was not smooth cornering as it normally is. I had to slow down, & take the curves at 35, otherwise the rear was jerky. My understanding of the PSM is that the components mentioned before keep the car stable cornering at higher speed.
I also noticed the car driving weirdly at slower speeds, the car breaking & slowing down on some curves, even tho I was not applying the brakes, and the cruise control was not engaged, which can slow the car when it'd going downhill.
The reason I say PSM was off was the car was hard to control, and it was like a 200# lead weight was in back, shifting from side to side. It was not smooth cornering as it normally is. I had to slow down, & take the curves at 35, otherwise the rear was jerky. My understanding of the PSM is that the components mentioned before keep the car stable cornering at higher speed.
I also noticed the car driving weirdly at slower speeds, the car breaking & slowing down on some curves, even tho I was not applying the brakes, and the cruise control was not engaged, which can slow the car when it'd going downhill.
08-11-2021, 12:13 PM
#5
Intermediate
Thread Starter
What is DWS?
The new tires are Continental Extreme Contact 295 30 ZR 20 XL. The old tires were Continental Extreme Contact 295 30 R 20, basically the same as the new tires. The PSM is for stability. I described how the yellow PSM image has been flashing when I take a tight corner with the new tires. Steve DeJung, the Porsche mechanic, said that it seemed that the PSM was switching off, leading to the instability and lack of control in cornering. With the new tires, I have to corner very slowly, like I'm driving an old low rider, otherwise the yellow image starts flashing, and it's unstable.
I wondering if what's causing this is the tires are not weighted property, or they need alignment?
The new tires are Continental Extreme Contact 295 30 ZR 20 XL. The old tires were Continental Extreme Contact 295 30 R 20, basically the same as the new tires. The PSM is for stability. I described how the yellow PSM image has been flashing when I take a tight corner with the new tires. Steve DeJung, the Porsche mechanic, said that it seemed that the PSM was switching off, leading to the instability and lack of control in cornering. With the new tires, I have to corner very slowly, like I'm driving an old low rider, otherwise the yellow image starts flashing, and it's unstable.
I wondering if what's causing this is the tires are not weighted property, or they need alignment?
08-11-2021, 12:24 PM
#6
The stability program is to correct driver mistakes, it is NOT to enhance vehicle performance but to create a safety catch by trying to keep you on the road. The flashing yellow light is to let you know the system has intervened, the system intervenes by applying the brakes.
I thought you had gone from summers to all seasons but that is not the case.
You might have a terrible alignment, wheel weights have nothing to do with this.
I thought you had gone from summers to all seasons but that is not the case.
You might have a terrible alignment, wheel weights have nothing to do with this.
08-11-2021, 12:35 PM
#7
Nordschleife Master
Also, new tires are slippery. You have to put some miles on them for that top slippery layer to wear off.
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Alansglide (08-16-2021)
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08-11-2021, 02:38 PM
#8
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Sounds like your PSM is coming on in conditions when it should not be. It should only intervene when you are doing extreme cornering and start to lose control. You are describing relatively modest cornering which should not activate PSM. I don't see how tires would affect this unless you had the wrong size or type. Otherwise my guess is you have a PSM problem that is coincidental to the new tires.
If your PSM was shutting off, you would lose control when attempting an extreme corner way too fast. But that is not what you have described.
If your PSM was shutting off, you would lose control when attempting an extreme corner way too fast. But that is not what you have described.
08-16-2021, 01:53 PM
#9
Intermediate
Thread Starter
It’s the PSM yellow warning light that comes on whenever I take a tight corner. This has never happened before.
Wheel Works informed me that the new Continental tires were “All terrain” for year around use, with a tread pattern that deflects water. And that the old rear tires were “Summer”, the same tread pattern as the front tires. Wheel Works aligned the wheels, but the PSM warning light still comes on when I’m cornering. Wheel Works said they’d replace the tires I have w “Summer” tires at no charge, all I’d have to pay is the freight. That’s what I’ll do.
Wheel Works informed me that the new Continental tires were “All terrain” for year around use, with a tread pattern that deflects water. And that the old rear tires were “Summer”, the same tread pattern as the front tires. Wheel Works aligned the wheels, but the PSM warning light still comes on when I’m cornering. Wheel Works said they’d replace the tires I have w “Summer” tires at no charge, all I’d have to pay is the freight. That’s what I’ll do.
08-16-2021, 02:00 PM
#10
08-16-2021, 03:41 PM
#12
RL Community Team
Rennlist Member
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As mentioned above, PSM is working as intended. Blinking means it's intervening. You would get a fault message in the MFD if it were deactivated or malfunctioning.
Wheel balance or tire compound will not disable PSM as it doesn't care about these things, it cares about wheelspeed.
You're some 10psi too high on the rear tires, and given your phrasing, you're likely 6-8 psi too high up front too. Look into deflating your tires to comfort pressures, not full load pressures. Full load is for, what the name implies, a full load that you likely aren't carrying, as well as hitting the 190+mph top speed. You're on street tires, presumably driving on the street, so there is little reason to have them inflated so high.
You're also on mismatched tires, which you've discovered. Sounds like you are on DWS06s instead of ECSs. The DWS06 will be a downgrade in traction compared to the ECS when in dry, warm environments. What you're feeling is a softer sidewall and less sticky tire compound. Welcome to all-seasons.
Wheel balance or tire compound will not disable PSM as it doesn't care about these things, it cares about wheelspeed.
You're some 10psi too high on the rear tires, and given your phrasing, you're likely 6-8 psi too high up front too. Look into deflating your tires to comfort pressures, not full load pressures. Full load is for, what the name implies, a full load that you likely aren't carrying, as well as hitting the 190+mph top speed. You're on street tires, presumably driving on the street, so there is little reason to have them inflated so high.
You're also on mismatched tires, which you've discovered. Sounds like you are on DWS06s instead of ECSs. The DWS06 will be a downgrade in traction compared to the ECS when in dry, warm environments. What you're feeling is a softer sidewall and less sticky tire compound. Welcome to all-seasons.
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jimmiejam (08-19-2021)
08-18-2021, 03:45 PM
#14
[QUOTE=asellus;17610586
You're some 10psi too high on the rear tires, and given your phrasing, you're likely 6-8 psi too high up front too. Look into deflating your tires to comfort pressures, not full load pressures. Full load is for, what the name implies, a full load that you likely aren't carrying, as well as hitting the 190+mph top speed. You're on street tires, presumably driving on the street, so there is little reason to have them inflated
There’s a zillion posts regarding 991 proper tire pressure, this one is an interesting read
[url]www.edmunds.com/porsche/911/2013/long-term-road-test/2013-porsche-911-cabriolet-finding-the-right-tire-pressure.html[/url]
You're some 10psi too high on the rear tires, and given your phrasing, you're likely 6-8 psi too high up front too. Look into deflating your tires to comfort pressures, not full load pressures. Full load is for, what the name implies, a full load that you likely aren't carrying, as well as hitting the 190+mph top speed. You're on street tires, presumably driving on the street, so there is little reason to have them inflated
There’s a zillion posts regarding 991 proper tire pressure, this one is an interesting read
[url]www.edmunds.com/porsche/911/2013/long-term-road-test/2013-porsche-911-cabriolet-finding-the-right-tire-pressure.html[/url]
09-07-2021, 10:06 PM
#15
Intermediate
Thread Starter
The summer Continental tires were installed last week. The car corners much better - the rear no longer feels like it's shifting from side to side, like a 300# weight in the trunk is rolling from side to side ... making the car more difficult to control.
A big however, is that the yellow PSM warning light still comes on, frequently when I'm cornering, & driving more than 35 or 40 mph. The car feels like it's not tracking as well, the front is drifting thru the curve, tho if I turn the steering wheel a little bit, it immediately responds. The back feels heavy. It used to corner like it was a train on tracks. I could corner at 55 or 60, much faster than my Pinto, and it would just carve right thru, like a knife cutting thru a stick of warm butter. I can't recall the warning light coming on before two months ago, when I got the new tires.
Is it possible that some component of the PSM is not working, not stabilizing the car while cornering?
A big however, is that the yellow PSM warning light still comes on, frequently when I'm cornering, & driving more than 35 or 40 mph. The car feels like it's not tracking as well, the front is drifting thru the curve, tho if I turn the steering wheel a little bit, it immediately responds. The back feels heavy. It used to corner like it was a train on tracks. I could corner at 55 or 60, much faster than my Pinto, and it would just carve right thru, like a knife cutting thru a stick of warm butter. I can't recall the warning light coming on before two months ago, when I got the new tires.
Is it possible that some component of the PSM is not working, not stabilizing the car while cornering?
Last edited by Tomasphil; 09-08-2021 at 12:52 AM.