Cranks but won't start after being driven
 

I have a 1999 E320 4Matic, when I start the car in the morning or after it sits a while it starts immediately, when it is hot and i park the car and try to start it 15-20 minutes later it will crank but not start. I left it with my mechanic for a week, he could not duplicate the problem, of course after I took it home and stopped at the store for 15 minutes, came out would not start, left it sit at the store overnight, started right up. It starts every morning when heading to work and every afternoon when going home. Any idea?

Haru

Faulty CPS (crank postion sensor) would be my first guess. Read http://www.peachparts.com/shopforum/showthread.php?t=102905 ;)

I just had the same problem on my 99 e320 and had the crank position sensor replaced. It was around $100 with an hour of labor.

Same thing on my 98 E320. Replaced the "CPS" and problem went away.