Intermittent problem, if I turn the fob the car almost always cranks(if the engine turns over it always starts immediately.).
The independent Mercedes shop I go to swore it was the starter. Well, maybe, the new starter certainly cranks faster. But I still have the intermittent crank problem. Annoying.
Yesterday it took 4 or 5 try’s to turn over so I drove up to the shop this morning.
But it wouldn’t do it again.

I’m tempted to just drive the car until it takes 20 or more try’s to get the engine to turn over and start or stop working altogether. Right now the most it takes is 5 or 6 try’s.

I’ve only got 130k miles on the car. Any thoughts or advice? Another shop, go to the dealer? Should there be stored codes and if so what would they be?

Have different keys been tried?

Yes it could be the EIS and yes it may have codes stored; but, a DIY emission code type scanner won't go far enough into the system to access the codes.

Check out ECU Pro in Wellsboro PA.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Yes, two old ones and a new one from the dealer.

When the car won't crank do you see the glow plug light actuate normally when you turn the ignition key to position #2?

You should see the glow plug light illuminate for a second or two and then go out.

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98 Dodge-Cummins pickup (137K)
13 GLK250 (157k)
06 E320CDI (341K)
16 C300 (89K)
82 300GD Gelaendewagen (54K)

Yes, everything normal except occasionally won’t crank. If it cranks it’ll always start.

If an led light is temporarily attached to the solenoid wire and placed in a positional where you see it you'll know if voltage is reaching the solenoid. If there is a no start and the bulb is lit the problem is the starter/solenoid. If the bulb isn't lit then the starter can be assumed good and the problem elsewhere such as the EIS or something in the crank circuit.

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Did you actually see the glow plug light illuminate during an instance where the car wouldn't crank/start?

There is a know failure associated with a failing ground wire signal from the ECU that powers up various components that produces the same symptoms you are describing.

It's show/described here

https://www.youtube.com/watch?v=VRLNYL4LzQg

__________________
98 Dodge-Cummins pickup (137K)
13 GLK250 (157k)
06 E320CDI (341K)
16 C300 (89K)
82 300GD Gelaendewagen (54K)