[jerseyjoe]

A good friend has a 300M that stops after 30 minutes or so.Will start up again after it cools. No Codes. Dealer replaced the crank sensor and throttle position sensor, Guy is short on cash so going round and around with the dealer is possible and a new car is out of the question. The no code thing bugs me. Any Ideas?

 

[ImperialCrown]

Not everything will set a code, although a good OBD II scan tool (not just a code reader) that can read sensor information and live data might see what the problem is.
The crank position sensor was a good guess. Even with a bad cam position sensor, the vehicle should eventually start after several seconds of cranking (the PCM will eventually determine where the #1 cylinder is).
Try to determine if spark or fuel is missing when it doesn't start. This has to be diagnosed after stalling while the car won't start as nothing will probably show up while it's running.

 

[KOG]

Bad ignition switch can do this, but as noted above, check first for spark and fuel as a bad fuel pump can do the same thing.

 

[jerseyjoe]

Thanks for the leads, will check for fuel, Spark, ignition switch because it seems to happen more often the the heater running. Also I see that the ASD relay will not leave a code. The crank sensor or signal from it needs a closer look. It wouldn't be the first time roadway salt damaged wire connectors.

I'ii let you guys know

 

[jerseyjoe]

Friend said a throttle position sensor was replaced, he now uses it locally with no issues. From what I was informed here this is not the cure. I will let you know about any other developments.