Track day LIMP MODE mystery
THANKS,
Will
Last edited by wilburfierce; Sep 28, 2018 at 02:02 PM.




https://mbworld.org/forums/c63-amg-w...trol-help.html
but then I realized it was you asking the same question again.
It is definitely not oil temp. 260F oil temp is not enough to trigger limp mode - that happens around 278F.
As I told you in the May post, I had exactly the same symptoms. In my case, I also got an alert on the dash. Restarting the car would immediately clear the problem, but it would happen again the next time I had tire slip at an autocross. Replacing the gas pedal permanently cured it. Here's the thread:
https://mbworld.org/forums/c63-amg-w...ensor-cel.html
I had a similar problem in my W204 '08, so I installed the Weistec Oil Pan and secondary Oil Cooler (Morosso) in the rear bumper.
If you're doing a lot of tracking it is also a good idea to remove the Tranny Oil Cooler Fan as it impedes air flow at high speeds.
I also ran a secondary Tranny Oil Pump in the trunk.
Also blocking the hot air from the radiator rising into the cold air intakes will help alot.
It may be worthwhile shielding the ABS unit as hot air from the exhaust manifold/extractors will trigger "limp mode".





Seriously though, it’s not just for overheated oil. In my experience, whenever the ECU sees a sensor massively out of scope, it’s going to throw limp mode. 270’ish F for oil, would probably do the same if coolant went off the chart. If you have a massive drift or are accelerating through corners rapidly, unless the TC is totally off, that can screw with ABS/ESC sensors and wheel speed sensors and trip it or cut back power massively until everything’s back within spec. A bad MAF or O2 sensor can do it - MAF out of range is pretty common. I had a couple of random throttle body and misfire codes cause limp mode out of the blue on track just a month ago. I mean, think of all the sensors for steering input, throttle, yaw, ABS, not to mention all the engine sensors you can see via OBD2.
The best you can do is keep your car maintained and address the weak points as they come up. You can also adapt your driving style to mitigate some of the car weaknesses and avoid a lot of the causes altogether. I know that I drive this car much differently on track than previous cars I’ve had, and I’ve also made a lot of changes to make it more like the car I want to drive. It took me awhile to get it.
Or maybe you just need more wheel/tire for how you like to drive and go from there. I was getting this too, and once I went to wider r-compound rubber and coilovers to keep the car better planted it went away. I keep the TC always on “Sport” and it’s completely unobtrusive now (and I assume it has a more narrow parameter range tolerance than TC off for instance)
Last edited by BLKROKT; Sep 29, 2018 at 07:25 PM.

Seriously though, it’s not just for overheated oil. In my experience, whenever the ECU sees a sensor massively out of scope, it’s going to throw limp mode. 270’ish F for oil, would probably do the same if coolant went off the chart. If you have a massive drift or are accelerating through corners rapidly, unless the TC is totally off, that can screw with ABS/ESC sensors and wheel speed sensors and trip it or cut back power massively until everything’s back within spec. A bad MAF or O2 sensor can do it - MAF out of range is pretty common. I had a couple of random throttle body and misfire codes cause limp mode out of the blue on track just a month ago. I mean, think of all the sensors for steering input, throttle, yaw, ABS, not to mention all the engine sensors you can see via OBD2.
The best you can do is keep your car maintained and address the weak points as they come up. You can also adapt your driving style to mitigate some of the car weaknesses and avoid a lot of the causes altogether. I know that I drive this car much differently on track than previous cars I’ve had, and I’ve also made a lot of changes to make it more like the car I want to drive. It took me awhile to get it.
Or maybe you just need more wheel/tire for how you like to drive and go from there. I was getting this too, and once I went to wider r-compound rubber and coilovers to keep the car better planted it went away. I keep the TC always on “Sport” and it’s completely unobtrusive now (and I assume it has a more narrow parameter range tolerance than TC off for instance)
thanks . most informative. I think it is definitely related to "extreme driving" ( only time it happens ). Further, why the hell would the car be designed to go into limp with extreme yaw, etc when their target buyer is likely planning to track it ! Never heard of TC problems but sounds logical. Tires-I drive to the track and believe my Mich Pilot Sport R 4s are the best thing going for that. Love them. So you think coil overs may help? I'm not very knowledgeable- what's MAF ? I have a great shop and they said they can scan the car and see full history of the sensors, warning lights, and etc. that were tripped. I know going into the pits to restart works but is very frustrating because last time ( though "it's not a race" ) I had worked my way to the front and was lapping drivers in all 4 sessions when it happened. So changing driving style is not an option HAHA. I've finally learned the car and whatever I'm doing is working
Last edited by wilburfierce; Oct 4, 2018 at 09:40 PM. Reason: mis-spelling

Seriously though, it’s not just for overheated oil. In my experience, whenever the ECU sees a sensor massively out of scope, it’s going to throw limp mode. 270’ish F for oil, would probably do the same if coolant went off the chart. If you have a massive drift or are accelerating through corners rapidly, unless the TC is totally off, that can screw with ABS/ESC sensors and wheel speed sensors and trip it or cut back power massively until everything’s back within spec. A bad MAF or O2 sensor can do it - MAF out of range is pretty common. I had a couple of random throttle body and misfire codes cause limp mode out of the blue on track just a month ago. I mean, think of all the sensors for steering input, throttle, yaw, ABS, not to mention all the engine sensors you can see via OBD2.
The best you can do is keep your car maintained and address the weak points as they come up. You can also adapt your driving style to mitigate some of the car weaknesses and avoid a lot of the causes altogether. I know that I drive this car much differently on track than previous cars I’ve had, and I’ve also made a lot of changes to make it more like the car I want to drive. It took me awhile to get it.
Or maybe you just need more wheel/tire for how you like to drive and go from there. I was getting this too, and once I went to wider r-compound rubber and coilovers to keep the car better planted it went away. I keep the TC always on “Sport” and it’s completely unobtrusive now (and I assume it has a more narrow parameter range tolerance than TC off for instance)
thanks . most informative. I think it is definitely related to "extreme driving" ( only time it happens ). Further, why the hell would the car be designed to go into limp with extreme yaw, etc when their target buyer is likely planning to track it ! Never heard of TC problems but sounds logical. Tires-I drive to the track and believe my Mich Pilot Sport R 4s are the best thing going for that. Love them. So you think coil overs may help? I'm not very knowledgeable- what's MAF ? I have a great shop and they said they can scan the car and see full history of the sensors, warning lights, and etc. that were tripped. I know going into the pits to restart works but is very frustrating because last time ( though "it's not a race" ) I had worked my way to the front and was lapping drivers in all 4 sessions when it happened. So changing driving style is not an option HAHA. I've finally learned the car and whatever I'm doing is working
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running 30 minutes sessions in high speed group in S+/ Tc “sport”... change transmission/diff fluids yearly... oil/brake fluids twice a year... along with major service by dealer yearly.... have run the oem ContiSport 5p, Michelin 4S, Pirelli Trofeo R... No LIMP mode! Never.
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running 30 minutes sessions in high speed group in S+/ Tc “sport”... change transmission/diff fluids yearly... oil/brake fluids twice a year... along with major service by dealer yearly.... have run the oem ContiSport 5p, Michelin 4S, Pirelli Trofeo R... No LIMP mode! Never.
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