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I took my 991.2 TTS to Daytona last weekend for the annual Audi Club DE. The facility is wide open, uncrowded, and amazing!! There were about 200 cars total, split into 4 groups - 1 beginner/novice group, 2 groups of solo, and 1 group of "race cars". There was more carnage that I expected, but none on the banking, just in the infield section and bus stop. The cars ran the gamut from E46 M3s, loads of Corvettes of all years, even more Mustangs (including quite a few new GT350Rs), a few Ferraris, lots of Porsches, and even a few Audis - 3 or 4 being new R8's.
I have been looking forward to this trip all year, and the event had the makings for a truly exceptional opportunity.
Minor problem: My TTS as well as another 2014 991.1 both failed miserably on the banking. I got in exactly 1 lap over the three days without the car freaking out. Here's what I got when accelerating in the banking beyond about 120mph.
1) Sport Plus failure - reverted to Comfort
2) spoilers retracted - no aero
3) PSM failure - drive with caution, see dealer immediately
4) Suspension system fault - drive with caution
5) headlight control system failure
6) Lane change assist failure
7) AWD failure - drive with caution, see dealer immediately
8) PDK failure - I didn't get this one everytime
As you can imagine, this was rather unsettling to have the car give up right when you need it most. I spent the weekend trying to do a lap, getting these failures, and bringing the car back to the paddock to try to get everything to reset, which took 15-20 minutes each and every time. I tried running with PSM in + mode, and PSM off - neither made any difference. I had zero confidence in the car. I talked to my dealer numerous times during the weekend, and they talked with Porsche numerous times on Friday and Saturday. Apparently, this has happened "with some of the Driving School cars on some steep banking in Alabama" was all I got back. No admitting this was a known problem they could fix or intended to address. No further contact about follow up. Nothing. I've waited a week to bring this up to the forum, with the hope that I'd hear something back from Porsche. I spent the remaining sessions on Saturday afternoon and Sunday just running fun laps with some buddies in slower cars, and didn't get hard on the accelerator in the banking. Fun enough, but not terribly rewarding.
GT3RS guys were getting the PSM failure, but they would just turn it off and drive anyway. I didn't think it wise with all of the added failures to drive at 10/10ths in this situation.
I've had my TTS's on track more than 50 days, with never ever a single issue before this situation at Daytona. At this point, does anybody have any experience with this phenomenon? Any ideas on a fix or solution, besides not going back to Daytona next year?
This last image is of me nursing the car around turns 3/4 trying to get back to pit lane on the bottom of the banking so as not to get in anybody's way.
This -^ is, I suspect, the key. Obviously there's nothing catastrophically or even mildly wrong with the hardware. I'd wager that the fundamental issue is that the software is confused by the non-transient extra-high Gs enabled by the banking and has decided that one or more accelerometers - or perhaps the ECU running it - has failed.
Randy, does the cascade failure occur almost instantly once you're squarely on the banking? Or does it take several seconds?
Randy, does the cascade failure occur almost instantly once you're squarely on the banking? Or does it take several seconds?
It can take some time - not identically repeatable. Under a certain threshold, I could get through the banking, but just as long as I was not under more than probably 40% throttle.
What tires and what sizes were you running? OEM N-rated stock rubber?
Could be bad luck and timing with a sensor going out but I bet it's somehow related to disparity in wheel speed confusing the electronics forcing a safe mode.
That banking really stresses the outside rubber. Did your tire temps change much on the right rear? Did you pinch the tire at all?
What tires and what sizes were you running? OEM N-rated stock rubber?
Could be bad luck and timing with a sensor going out but I bet it's somehow related to disparity in wheel speed confusing the electronics forcing a safe mode.
That banking really stresses the outside rubber. Did your tire temps change much on the right rear? Did you pinch the tire at all?
Cup2 tires in OEM size. I checked the right rear tire repeatedly with no abnormal temp change...or I should say more than expected at Daytona. With the headlight failure, it makes me think it was related to the vertical orientation, since the headlights always try to stay parallel to the road surface (even though I was not using the headlights)
I don't see how running on banking would produce a wheel speed variance that's any different from driving on level ground.
The primary 'sensed' characteristics will be that the car is 'on a mountain side.' Possibly what is happening is that someone - likely a programmer in India that rides the bus to work, in conjunction with a lawyer who drives an old Saab - decided that once the sensors indicate a roll angle above some threshold for a certain number of seconds that the car must be about to fall over (off the mountain side) or that one or more sensors contributing to the roll angle calculation have failed.
If you can convince a Porsche technician with the PWIS laptop in data-logging mode to accompany you at Daytona you have a slighter-than-a-snowball's-chance-in-Hell of getting Porsche A.G. to look at it. You will at least - possibly - be able to determine what the computer(s) think is happening.
Very unsettling. Hope you can get to the bottom of this. It's probably a simple software or sensor calibration fix, but given how complex the system is, it's hard to do.
If you can convince a Porsche technician with the PWIS laptop in data-logging mode to accompany you at Daytona you have a slighter-than-a-snowball's-chance-in-Hell of getting Porsche A.G. to look at it. You will at least - possibly - be able to determine what the computer(s) think is happening.
I'm anxiously awaiting the PM from that Porsche tech/engineer. They used to monitor these threads a little bit...maybe somebody at Porsche can chime in, but I'm thinking the same as you on the rollover scenario.
Not to hijack the thread, OP, have any of these faults ever happened while you were not on that track? The reason I ask is that I had some of these warnings appear on my brand new car driving under normal conditions.
I picked up my TTS Euro delivery last month in Leipzig and drove to Berlin (about 100 miles). When i reached Berlin, i noticed that the transmission started skipping 2nd gear and would shift directly from first to 3rd and then to 5th. It happened a few times before I got to the hotel but I didn't think it was a malfunction and thought it might be just a function of engine speed and vehicle speed. When I stopped at the hotel, the car would not engage reverse and then a PDK failure warning showed up on the screen along with a warning to drive to the nearest Porsche center. The hotel management was nice and just left the car parked in front of the hotel overnight as the valet could not take it to the garage without a reverse gear. In the morning, a flatbed took it to the dealership. They checked the ECU (maybe PSM?) and told me that they found some error codes in the computer. They said they deleted the codes and that everything is fine. When I asked what would cause the error codes, they just said sometimes these things show up in computers and they just delete the codes and that does the trick. As going to the dealership had disrupted my vacation plans already, I just decided to not ask too many additional questions and left. I drove the car about 900 miles after that in Germany and the Czech Republic and the fault did not show up again. When I returned the car for shipping back at the Leipzig factory, I asked them to check it and make sure I don't have a lemon.
The car just hit port in the US and I will likely pick it up in 10 days from my dealer and am hoping they have done what needed to be done and that the fault does not show up again.
Randy,
This is known issue at Daytona due to the curved banking causing high differential speeds on the inside tires versus the outside. I didn't have a problem in the GT3 but many AWD Pcars do. It was discussed in our track walk and people were told to expect it. I don't remember a solution being offered. I would think staggering the tire pressures higher on the outside would help, and is recommended, but not sure it would solve the problem.
The peak axial g loads are actually less at Daytona. Most loading is down into the payment due to the banking. I generated more peak g loads at Sebring (1.56) than Daytona (1.32), but you will generate those forces for a longer period of time at Daytona.
Randy,
This is known issue at Daytona due to the curved banking causing high differential speeds on the inside tires versus the outside. I didn't have a problem in the GT3 but many AWD Pcars do. It was discussed in our track walk and people were told to expect it. I don't remember a solution being offered. I would think staggering the tire pressures higher on the outside would help, and is recommended, but not sure it would solve the problem.
The peak axial g loads are actually less at Daytona. Most loading is down into the payment due to the banking. I generated more peak g loads at Sebring (1.56) than Daytona (1.32), but you will generate those forces for a longer period of time at Daytona.
I guess the whole car freaks out. It's a well kept secret! Appreciate the comment. Porsche should offer some solution or something to mitigate this. GT-R and other AWD cars don't seem to suffer this issue.
I am no expert on the 991 TTS software, however, I have plenty of user and technical experience with other cars at Daytona, including current Gen Ferraris, which have more sensors and lines of code than is almost digestible
A "common" issue seen at Daytona is the different sensors see parameters that individually, or collectively, show readings outside normal limits; the ECUs (collectively) cannot reconcile and thus throw all sorts of codes.
A very typical scenario is a street car is "Sport" mode (i.e. normal stability, traction, et al) exiting turn 6 will toss the yaw sensor off it's limits as the car sees the lateral g's due to the banking, and aggregate g's mixed vs. the speed (most people think they are flying coming onto the banking, they're really not...). Less if an issue coming out of the bus stop as the car is typically going a bit quicker entering the banking
In the Challenge car, if you have the TC on setting 1, and the typical formation lap is going too slow going onto the banking, you'll get a TCS and/or ABS failure within about 10 seconds. Again, the sensors are giving inconsistent readings that the software sees as beyond limits. We HAVE discovered from time to time that we've had bad accelerometers and/or sensors, but that tends to be rare. In this case, we've learned to "cheat" by staying on the apron, or stack up back in turn 5 to carry enough speed when we hit the banking - and worst case, we can do a hard reset going down the back straight (which is stupid, but works).
Based on the data we look at, the differential wheel speeds (on all 19 or all 20 inch wheels) is closer than you think. Remember that differential (%) will be the same if you're doing 15, 115 or 150mph. (I say that because wheel speed sensor issues can wreak havoc with the ABS so we watch this).
Unsure what the Porsche AWD software might buried in there.
12-18-2016, 10:56 PM
FAIL at Daytona
