Mercedes Benz repair: hard starting, air flow sensor, mass air flow sensor

Question
my cl 500 has a hard time starting when warm.starts right up when cold.check fuel pressure all typical when cold or hot.no fault codes with a obdII scanner.dont know if there is faults in the factory system.runs great other than hard starting when warm

Answer
Generally this is a mas air flow sensor problem. i have seen this on a few CL500. Not always the case, but I would remove the mass air flow sensor located below the air intake, apply lubricant to the rubber seal on top and bottom of air flow sensor then reinstall.
The problem is usually generated from a slight air leak from the air flow sensor seal.