I am really hoping someone here can help me.

I bought this car in November 2015 and have had nothing but issues with it (of course, after any contract grace period, and no warranty) I honestly only drove it for about 1 month since that time. (sorry in advance if this is long)

• First problem was water pump, car leaked coolant everywhere and needed a tow. I got that replaced. Car worked for a few days.
• Next, the car wouldn't start. I was stuck in an underground parking lot, so the tow truck couldn't get it. We pushed the car as far as we could and when I got in to put it in neutral it started?? Diagnosis was fuel pump, so I put a new one in. Car worked for a few days.
• Suddenly back to car won't start. Changed the CPS. No fix.
• I took the car to a dealer, paid $450 for a diagnosis that I need a new ECU (ECM). Based on what they wrote on the invoice their methods were not too scientific. "check codes, no codes, intermittent signal from ME, ME has silicone looks like it's been tampered with, tapped on ME car started, need new ECU". $2500+++
• I opted to get the ECU cloned with another good one I bought, and based on what I have been told it works 99% of the time.
• Now I can get the car to start every time, but it cuts out about 3-4 seconds after. Every time.
• The guy who cloned my ECU also has the SDS tool so he came over, scanned the car, no codes.
• I found 2 dead relays under the hood, replaced them. No fix.
• We checked the battery and found it low, so I charged it up as I read that ECU needs something like 14+ volts. Once charged, tried it. No fix.
• Yes, tried both ECUs, same conditions.
• Checked the MAF also by disconnecting, same issue.

I am LOST here....the car starts everytime, runs great for the 3-4 seconds, can be revved and everything, no CEL, so I have no idea what it is...can someone please help?

The only outstanding theories I have left to check (based on scouring the internet) are:

1. Fuse panel under the hood replacement.
2. Fuel Filter.
3. Can this be a DAS thing, and I lost sync between key and ECU and I need a new one programmed? (My wife lost my other one)
4. EIS?
5. ESL?
6. Could it be the alternator? I tested it and it does not appear to be working, would it cause this type of scenario?

I spent almost 50% of what I paid for the car and still have a really nice looking lawn ornament in the driveway.

Anything electrical or electronic should throw a code.

Maybe the key is the issue?
Maybe power supply to the ECU?
Plugged fuel filter?

Was this vehicle swamped or something? Check the battery compartment for corrosion.

Do you have airmatic?

I had a 2006 ML500 where the airmatic relay blew and damaged the fuse panel which caused a similar problem.

You may have tried this already, but as the other person said, it could be your key. This hasn't happened to me in the R350, but in my Audi, this is how the immobilizer acted. Runs, then immobilizer cuts ignition.

Thank you very much for the responses.
I wonder if the key somehow got 'unprogrammed' along the way?

I wanted to tackle this from cheapest fix in ascending order, I think the key is a straight order from MB, right? Give them my VIN and away I go?

Well I can't say for sure, but if you don't have codes, I would at least call the stealership and ask what key programming costs, then you can see if it's worth the risk. You may want to post in the ML forum just incase as they have very similar ECUs, modules and obviously the same engine.

Sorry you're going through the wringer with your car. I'm in the same boat - engine blown

BUMP?

Is this a diesel or gas unit? I'm presuming it is a gas jobby as the diesel is a 320 in that year.
Looks like the fuel pump prime is working. You have spark and injector pulse as well as timing and fuel ratio. You need to go to the fuel pump relay and see what is missing. Could be relay control from the ECM or relay power. It could be also no fuel pump power to relay. I will try and pull up the electrical circuit diagram and see if this a 2 relay system. If you feel comfortable doing so, you can jump the power at the relay to bypass the ECM control. If car runs fine, then we are a lot further in our diagnostics.

Thank you!
I am not that comfortable, but I am great at following instructions... ;-)

I checked the wiring diagram from one source and that one wasn't too clear. I will check with Mitchell1 tomorrow. Do you have a test light probe?

I do.....

Foondar, any updates ? Always good to know a solution if you found one in case

Nothing yet, keep in mind...every attempt is close to another $1000 to determine...and I don't have that freely to throw around.

I am going the key route, so my fingers are crossed.

Best of luck to you !

Update....

Got a new key $350 - Still no fix
MB dealership took car in, diagnosed it to be the fuse panel (see, on my list). $1370
Told it worked, mechanic drove care around and when I went to pick it up....would not start.
This time different, sputtering as though no gas and could not get it to crank.
Car remains at dealership

....to be continued....

For those that care, it looks like I have closure.

looks like the fuse panel was MOST of the fix, the rest of the fix was thanks to the amazing work performed by James at http://www.mbcluster.com who cloned my bad ECM to a working one....

The car is on the road and seems to be working great? Although I am nervous everytime I get into it now.

I really need to recommend mbcluster.com to all everyone, this guys went above and beyond to help me, even coming to my house to run the STAR diagnostic to see what was up.

(Car is now up for sale, fyi. ;-))

Way to to Foondar! Glad it's all fine again, shame you're selling

Awesome. Glad it worked out. Love how Mercedes calls it a "smart" fuse panel - clearly it's the opposite.