So I've been having a starting issue with my 96 e320 lately and I've finally given up trying to diagnose the problem myself and decided to turn to the community. Sorry if I seem like I'm rambling, but I'm just trying to be as detailed as possible:

It first happened a few weeks ago when I was trying to leave for work and the car would crank but it wouldn't start. It wasn't making any sign of combustion, so of course the first thing I do is turn to Google, and the crankshaft position sensor shows up everywhere. Tried cranking the car a bit later in the day and it started right up. Began taking it for a drive and it quit after about 100 meters. The next morning it wouldn't start again. The symptoms seemed to match, so I ordered a new cps from autozone (first mistake, not oem).

Attempt #1: Replaced the cps that same night, only to find that it made no difference at all. The next thing I did was order a new CAMshaft position sensor because a couple people supposedly fixed their starting issue by replacing it (shouldn't it still run without it though?).

Attempt #2: replaced the camshaft sensor. Car started right up and idled fine. Fixed, right? The next day at noon, it started again, but it only drove down the street before it quit... Again... Over the next few days, I confirmed that it wouldn't start in the mornings or late evenings, but it would start at midday, and run just fine once warmed up. Additionally, the check engine and srs lights were on but there were no codes... Might be another issue entirely, but still odd... So I ordered another CRANKshaft sensor, but this time it was an oem one from autohausaz.com (oem was cheaper anyways. Imagine that?). In the days before the part shipped in, I was able to confirm that it wouldn't start in the mornings or late afternoon, but it WOULD start midday and run great once warmed up... And as long as the engine was still warm, it would always start up again.

Attempt #3: replaced cps with new oem one. (also replaced fuel pump since mine was leaking, so it definitely rules that out) Car started perfectly. I thought the war was finally over because it was late at night on a cold engine, where it normally wouldn't have started. Next morning? Didn't start again, of course. This is when I decided that my car has a mind of it's own and just hates me. This is when I decided to turn to you guys... I'm assuming that it's probably a simple stupid electrical issue, knowing that my model has some biodegradable wiring (wtf mercedes lol). I still think it may be related to the cps in some way since I don't get a reading on the tachometer when it's cranking. I cleaned the connector contacts to both sensors, but to no cigar. Has anyone ever traced the cps wire? I'd like to put a tester to it a bit farther up. I'm up for replacing some wire if need be. It could potententially be moister screwing with the signal? I live in Florida so humidity may play a big part in this. I suppose I should check for fuel pressure and spark as well. What else would you guys recommend at this point? Am I really supposed to see an rpm reading while cranking? The tachometer reading (or lack thereof) is the only reason I'm assuming it's related to the cps at this point.

 

Some would say it "could be" K40 relay...

 

Needs setting to daylight saving. Ha ha LOL

 

Haven't thought about the K40 relay since none of the symptoms seems to point to it, but you did however get me looking at wiring diagrams for the related areas. I'll see if I can pop open the cover to the engine control module next time I have a chance and see what I can do in terms of electrical testing there. (I presume it's the black compartment next to the cabin air intake)

 

There is no such thing as CEL and no code.
Get the codes- that's what they are for.

 

Yeah I figured there had to be codes. It was tested with two decent consumer grade testers, but maybe that's the problem... Anyways, I do have a friend who can test the entire Ignition system, but they're out of town. And I don't have an oscilloscope of my own yet (or much knowledge of the electrical system) to do basic testing myself.

Since my car seems to start fine once the sun warms it up, I went the high tech route of using a hairdryer to test different points of interest and ended up at the ignition coils as you mentioned. Thank God they're not too expensive (relatively speaking) and they look like they need replacing anyways. I'm not too sure why one problematic Ignition coil would seemingly prevent the others from working, but that's what I'm going with for now.

 

Love the solution that give you the option of fixing the car without paying high dollar to DAS Xentry spammers
You still should read the codes at your convenience as they will explain more and they will stay stored till you clear them.
I would think that with several misfires the computer simply shuts whole engine down, but this is wild guess.

 

Alright, I should be able to get a reading once my friend is available again.
For now I'll just post what happens once I replace the coils.

Thanks guys.