Hey guys. Last week my car died at low speed in a parking lot. Every light on the dash was on and the A/C was still blowing, but the engine had stalled out and would crank but not fire. I let the engine cool down and it started up again, and made it home. The next day, I did some diagnosis (essentially just doing some WOT pulls) and the car pulled fine for the first one. A few miles later I punched the car at 50 and it hesitated, pulled a little, then I could feel the engine struggling. I turned it off and coasted to the side of the road. It would crank but not start. Again, I let the car cool down and started it, got home. After this ordeal I ordered a new Crankshaft Position Sensor from FCP Euro (Bosch part) and installed it today. Took the car on a shakedown run and it ran beautifully, pulled really hard. However when I was pulling back into my neighborhood... I think you can see where this is going. Yep, the car died on me at low speed while I was coming to a stop sign. Let it cool down, restarted, got home and parked. After this I restarted the car and let it idle in my driveway and after about 5-7 mins, it died again. I started it one more time and let it idle right up until the point where I could feel it about to stall out. I gave it some gas (up to about 2200 rpm) to catch the stall and held it there for a few seconds. As soon as I let off the gas, it stalled out. Because I was able to catch the stall, it makes me think it isn't fuel related. That, and I had the fuel system recall done only 5 months ago. So I'm at a loss now, the symptoms seem like classic CPS failure but the issue is still occurring after the replacement. Could it be the MAP sensor? Maybe a vacuum leak? The Y pipe connector going to the throttle body is missing the back clip but it still seems to be making a seal. Any input would be appreciated, I'm stumped.

 

Have you scanned it for codes?

 

I have not, the car isn't throwing a CEL but I realize that probably doesn't mean anything. I don't have access to star so what would be my best bet for getting the codes scanned? I'd like to avoid paying the dealership to do it.

 

Check your fuel pump connector to see if it looks burnt.

 

Start here. This sounds like the proverbial "damaged fuel pump relay".
https://mbworld.org/forums/w211-amg/...nge-issue.html
and here:
https://mbworld.org/forums/w211-amg/...intenance.html

 

Thanks bbirdwell. I won't have time to check that until later tonight but I'm not driving the car in the mean time. Really hoping this didn't fry any part of the fuel system because that means a lot of $$$

 

I snapped a picture of what I believe to be the relay you guys were describing (please correct if not) and there does indeed seem to be some discoloration like it was burning up. What do you guys think?



However there does not seem to be anything out of the ordinary under the backseats.

Passenger side:




Driver side:

 

I don't usually recommend randomly replacing parts but the relay is cheap and should probably be replaced every few years anyway, probably a good place to start. I keep one in the glove box, can thank bbirdwell for that idea.

 

Pretty sure the relay got cooked. However, could this really be my problem? Seems like most people that had this issue couldn't even start their cars

 

Luckily it doesn't look like they were damaged in the same way that was detailed in one of the links bbirdwell posted. It does look like the dealer put little green marks to see if anyone goes poking around down there though... interesting haha

 

Haha, did you look at that picture?! And you ask could it really be your problem, haha, good god man.

 

Well yes it's obviously a problem, just figured there might be something else going on since I can actually start the car and run it up to operating temps with no problems. Alas, I'm sure you're right and I do look pretty stupid questioning it.

 

You can have full loss of connection. You can also have high current, consequently high temperatures, melted plastic, deterioration of the wiring and spade terminals without complete failure. Of course full failure is imminent.