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(still not really heavy braking, not going real fast as still learning track).
This happened twice to me today on the track, and once over a year ago on the track. During braking and downshift, the car loses power and will not rev past idle. The engine doesn't die. No CEL. Seems like a "limp mode". I pull over, turn it off, and restart, and no problems. I have heard/read somewhere about this happening if brake and gas are pushed at the same time. But, I have also done hard braking and blipping the throttle for downshifts on multiple laps in several sessions. Interesting that this happened at same point on track today - end of straight, braking and downshifting to go into the bus stop at NCM.
Ever since Toyota's *"Christine" moments, almost all car manufactures have a "OMG s/he stepped on the brakes!!" "Go to idle NOW!!!" bit in the ECU.
Does this happen with PSM ... etc. off?
I found this out on my 2003 after the first wash. I usually take a short drive and drag the brakes for a bit to get some heat in them and dry them out. I did this in the 2003 and it shutdown to idle in less then 1/2 block.
*(May have too obscure for some of you youngsters)
http://en.wikipedia.org/wiki/Christine_(1983_film
)
throttle on first and then brake added will make it go into limp, brake first then throttle will go fine.
Have a tuner shut off the limp mode for full experience.
"Porsche fault code 408 - Function monitoring Torque comparison Signal implausible" shows up in Engine error codes.
Does not throw a CEL. Cleared the error code, and went back out. Happened about 4 more times. Always on hard braking at end of straight, with a blip and downshift. (still not really heavy braking, not going real fast as still learning track). But it seems that engine went to limp before I could blip to downshift. Perhaps went to limp before clutch went in. I was heel-toe'ing on two other corners without incident. (and with less heavy brake)
I am wondering if my fat foot is touching the gas pedal during heavy(er) braking prior to clutch-in and blip, and this is when the limp mode starts.
Quick turn off and restart and all is fine.
I'm guessing that you might be hitting the gas at the same time. When I had my Boxster, I was trying to use one of my old-school tricks for bedding pads (giving the car a little gas while braking downhill to really get the temps up), and I found out that the Boxster does NOT like it when you hit the brakes and gas simultaneously.
In my tip if I do more than about 5mph accelerator pressed and push the brakes a bit the engine will drop to idle. I can then push the accelerator flat and it does nothing. So there I have brakes full. Accelerator flat out. Car is idling until I let go of the brake. About 0.5 second delay and it's flat out acceleration. Interesting launch workflow for a tiptronic I thought.
This is a source reference. Confirm exact model applicability in the original material.
