"Limp-Mode" on track

[thedoctor]

Recently had the very frustrating issue of my car going into "Limp mode" during a track day. Is there any way this can be avoided? Car has JB and DP's with semi's on the rear, but I don't think this would be causing it? This literally happened after a few short laps of hard driving. Does anyone know exactly what causes the car to go into this mode? Is it engine temp.? Seemed like hard braking triggered it on at least some occasions.

Any info / advice would be greatly appreciated. Thanks guys.

[Used2be]

Originally Posted by thedoctor

Recently had the very frustrating issue of my car going into "Limp mode" during a track day. Is there any way this can be avoided? Car has JB and DP's with semi's on the rear, but I don't think this would be causing it? This literally happened after a few short laps of hard driving.

Are "semi's on the rear" a different tire from stock? If the tire diameter is much different from the stock diameter of the original set that might cause your limp mode problem. I can't tell you how much difference can make the car go into limp mode, but other owners have reported this happening with just street driving.

[thedoctor]

Originally Posted by Used2be

Are "semi's on the rear" a different tire from stock? If the tire diameter is much different from the stock diameter of the original set that might cause your limp mode problem. I can't tell you how much difference can make the car go into limp mode, but other owners have reported this happening with just street driving.

Yes, I mean "semi slick tires". I don't think it's that since I drive with those on the street too and have never had any issues.

[13M5F10]

Originally Posted by thedoctor

Recently had the very frustrating issue of my car going into "Limp mode" during a track day. Is there any way this can be avoided? Car has JB and DP's with semi's on the rear, but I don't think this would be causing it? This literally happened after a few short laps of hard driving. Does anyone know exactly what causes the car to go into this mode? Is it engine temp.? Seemed like hard braking triggered it on at least some occasions.

Any info / advice would be greatly appreciated. Thanks guys.

How were the engine temps? Was it possible the car got to a certain operating temp it shut it down?

[lemetier]

Originally Posted by thedoctor

Recently had the very frustrating issue of my car going into "Limp mode" during a track day. Is there any way this can be avoided? Car has JB and DP's with semi's on the rear, but I don't think this would be causing it? This literally happened after a few short laps of hard driving. Does anyone know exactly what causes the car to go into this mode? Is it engine temp.? Seemed like hard braking triggered it on at least some occasions.

Any info / advice would be greatly appreciated. Thanks guys.

Limp Mode can be caused by a number of factors, especially with track use. It doesn't have to be a direct engine trigger either. Some conditions force the engine to go into limp mode due to other systems reaching their hard limits. The only way of really knowing the cause is to scan and read the codes. Brakes, DSC, and VDM can all trigger engine limp mode. Brake fade compensation will trigger it rather than modulating pedal position, and DSC Module can trigger it when lateral loads exceeded 1.2g for more than a specific time (the aux oil scavenge pump and catch cans are limited to 1.2g sustained lateral load).

What tire setup are you running specifically? (Type and size)

What DSC mode was active? (MDM or off)

What was the ambient condition? (Temp, elevation, humidity)

[thedoctor]

Originally Posted by miamiten

Limp Mode can be caused by a number of factors, especially with track use. It doesn't have to be a direct engine trigger either. Some conditions force the engine to go into limp mode due to other systems reaching their hard limits. The only way of really knowing the cause is to scan and read the codes. Brakes, DSC, and VDM can all trigger engine limp mode. Brake fade compensation will trigger it rather than modulating pedal position, and DSC Module can trigger it when lateral loads exceeded 1.2g for more than a specific time (the aux oil scavenge pump and catch cans are limited to 1.2g sustained lateral load).

What tire setup are you running specifically? (Type and size)

What DSC mode was active? (MDM or off)

What was the ambient condition? (Temp, elevation, humidity)

Have Toyo Proxes R888's on the rear (315/30 ZR20) and stock tires up front (Pilot Super Sports 265/35 ZR20)

Was running in MDM mode. Do you think running with DSC off reduces the chances of going in to Limp Mode?

Ambient temp. was around 28 degrees Celsius, elevation is approx. 1700m above sea level and humidity is on the normal / low range.

What confuses me is that I ran exactly the same set up with same conditions around another longer / faster track and had no issues. But around this other specific track (which is much tighter) the M5 seemed to hate it, going in to Limp mode as explained.

[JetBee]

This happened to me too. It turns out to be spark plugs.

[JetBee]

Just take it to the dealer.

[thedoctor]

Originally Posted by JetBee

This happened to me too. It turns out to be spark plugs.

Spark plugs? Surely if that was the cause I would be experiencing it going into limp mode regularly, even after the track during road driving? The limp mode issue I had on the track was temporary, with the car returning to normal after a few minutes. I've never had the issue after that, and it has been a few months past.

[gmd2003]

Originally Posted by thedoctor

Spark plugs? Surely if that was the cause I would be experiencing it going into limp mode regularly, even after the track during road driving? The limp mode issue I had on the track was temporary, with the car returning to normal after a few minutes. I've never had the issue after that, and it has been a few months past.

It's the BMS module 100% . Not really a track friendly way of tuning ( stage 1 just tricks the car into running more boost and letting the ECU sort it out . EGTs( Exhaust gas temp ) will get too hot with track use . Happened to me with my M6 and BMS stage 1 set at 3.5 . The actual JB4 with boost control module is a better option but still need to be on minimal settings for track work . Running race gas will help but you have to really dial the settings back for circuit use . As you become a better driver the issue will only get worse . And yes the BMS could have damaged your stock plugs bc of cylinder temps/knock on track . It did mine .

[lemetier]

Originally Posted by thedoctor

Have Toyo Proxes R888's on the rear (315/30 ZR20) and stock tires up front (Pilot Super Sports 265/35 ZR20)

Was running in MDM mode. Do you think running with DSC off reduces the chances of going in to Limp Mode?

Ambient temp. was around 28 degrees Celsius, elevation is approx. 1700m above sea level and humidity is on the normal / low range.

What confuses me is that I ran exactly the same set up with same conditions around another longer / faster track and had no issues. But around this other specific track (which is much tighter) the M5 seemed to hate it, going in to Limp mode as explained.

I'm inclined to agree with gmd2003. With a rough calculation, using standard barometric pressure, the density altitude is way up there (2500-2700m) and the piggyback is probably causing some hard limits to be reached in regards to inlet, exhaust temps, and AFR demands prematurely. Maybe someone with deeper knowledge of the S63 will respond to the behavior of a piggyback with a density altitude over 8000ft.

[thedoctor]

Originally Posted by gmd2003

It's the BMS module 100% . Not really a track friendly way of tuning ( stage 1 just tricks the car into running more boost and letting the ECU sort it out . EGTs( Exhaust gas temp ) will get too hot with track use . Happened to me with my M6 and BMS stage 1 set at 3.5 . The actual JB4 with boost control module is a better option but still need to be on minimal settings for track work . Running race gas will help but you have to really dial the settings back for circuit use . As you become a better driver the issue will only get worse . And yes the BMS could have damaged your stock plugs bc of cylinder temps/knock on track . It did mine .

Thanks for the valuable info! That's very disappointing if the cause is the BMS module. So am I understanding you correctly that I should turn the boost setting down as low as possible to reduce chances of going in to limp mode? If so, what setting would be advised? Or should I disable the BMS module completely (Map 0) when doing a track day?

[boots]

When I had my bms I ran at Texas world speedway. I had no such issues w limp mode during or after. But after approx after 30k miles of use it did mess w my coils. Replaced plugs, coils and removed the bms for a tune

[thedoctor]

Originally Posted by boots

When I had my bms I ran at Texas world speedway. I had no such issues w limp mode during or after. But after approx after 30k miles of use it did mess w my coils. Replaced plugs, coils and removed the bms for a tune

What boost setting were you running with your BMS during that track day?

[boots]

I used 3.0 for everything. I had no issues using it after adaptation. But a proper tune is so much better performance and the correct method for our cars

[lemetier]

Originally Posted by boots

When I had my bms I ran at Texas world speedway. I had no such issues w limp mode during or after. But after approx after 30k miles of use it did mess w my coils. Replaced plugs, coils and removed the bms for a tune

This is quite an unusual operating environment with the op's case, and certainly not one many members here would encounter or think of. The elevation is already over 5600' ASL. Add to that the heat 28C (95f), low to avg humidity for South Africa (60-80%), during track use, things can quickly run out.

Octane can become a factor (when the boost pressure available can no longer provide Atmospheric Sea Level at the intake Manifold, let alone over 1bar), higher octane fouls plugs quite easily as there isn't enough oxygen to facilitate complete combustion (so yes to the OP check the plugs as well, especially if you have a recent build with the Delphi Coils and CVO injectors
Combo). Forced Induction, Direct Injection, Dual VANOS with a very wide adjustment range, and Valvetronic do help, but they don't make the engine immune to high altitude "sickness". The difference between Turbo-Charged and Turbo-Normalized comes into play, but is way outside my engineering skills.

Some more recent S63TU (along with S55 and N63TU2) have a better ability to cope since they have different DME, Fuel Delivery System, inward vs outward metering valves on the injectors, updated coil packs (with unique cylinder heads), and revised wastegates.

I lived part of the year for over a decade in an area where the main city (office) was 7800' ASL, but the suburbs where home was located is 8900' - 9400' ASL. Ambient temps were 19c-21c year round. Even lightly armored cars are heavy, so combining that penalty with the elevation and extremely steep roads, a bit more oomph is certainly wanted. I tried piggybacks but only two were ok if not pushed too hard (in-law's 1M Coupe and our X1 30i/N54 - strange local market version I haven't seen anywhere else). N63B40, N63B44TU, S63, S63TU were never happy. There aren't many major metropolitan cities at very high altitudes, and the subset with high ambient temps is vastly smaller at that. Turbocharged Gasoline vehicles are, surprisingly, not very common either. Usually larger displacement N/A variants with shorter final drive ratios and Turbo-Diesel are the most prevalent.

[boots]

Yes when you factor in all of those elements especially the High elevation I agree things go bad