if I run my e320 until it gets to normal running temperature and switch of the ignition and let it sit for anywhere from about 20 minutes - 2 hours (a.k.a if I don't let the engine return to its cold outdoor air temp) it has a difficult time starting. the engine hesitates to start and requires double the cranking time before it fires up.

if I shut off the warm engine and start it back up within 15 minutes it starts as it normally should.

I took the first preliminary step and replaced the plugs, but that didn't solve anything.

anyone have a similar experience, or advise on what the problem may be?

 

cps (crankshaft positioning sensor)??? that would be my guess, and they are not that expensive, around $70-80. haven't changed one yet, but from what the others have mentioned, it takes like 5 minutes to change if you know where it is located and have the right tool.

 

Mine did this a couple of times when I put 92 octane gas from BP. When I use 91 octane from other places it is fine. We don't have any other places with 92 or higher octane in stupid Iowa besides BP. you might try a different brand of gas or go one octane up or down to see if it makes a difference (I'm not suggesting going below 91 though). I would love to run mobile1 93 octane if it was available here.

 

I have read other similar complaints leading to the CPS (Crankshaft Positioning Sensor) My guess is your CPS dying as tirona mentioned.
Here is one of the complaints I found with same symptoms you have.

LINK: https://mbworld.org/forums/showthrea...&highlight=cps
Search for CPS and you will find many with same symptoms on this forum.

 

doesn't sound like a crank sensor the symptom would not start when hot and would re start after sitting 20-30 minutes, you might be losing fuel press. and vapor lock is occurring,fuel pressure regulator i believe it is part of the fuel filter on that model

 

reviving this old thread. my newly bought mb does exactly the same thing--and i just changed the crankshaft and cam sensors so i know the problem is not cause by those (of course, there's always the possibility that i just happened the bought (new) bad sensors.

is there a way to verify if it's the "fuel pressure regulator"? searched these key words in title search and only one hit by pelican parts.

sorry, i'm new to MBs and am a new DIYfer. thanks in advance!