2007 S550 Bad DME?
08-22-2020, 02:59 PM
#1
Member
Thread Starter
2007 S550 Bad DME?
Hi all,
Hoping someone here can provide some insight with my situation.
I purchased a 2007 S550 with bad motor (balance shaft). I found a replacement motor from a 2008 S550 with low miles. I put the motor in and the car fired right up and motor is healthy. Cleared codes and turned it off. Buttoned everything up and started the car again with hopes of test driving. A few seconds later, CEL came on and engine started misfiring. Scanned and had misfire codes for cylinders 7 and 8 (P0307 and P0308). Checked spark plugs and they look new. Checked coils and they looked good, but performed swaps anyway. Codes did not follow. Tested injectors and no issues.
Pulled a coil from the old motor and put a spark plug in it and grounded it. Attached to cylinder 6 first and had spark. Attached to cylinders 7 and 8 and had no spark. Now narrowed down to harness or DME thinking there is no signal reaching the coils. Checked continuity on the wires from DME to the coils and had continuity.
So this leads me to believe this is a DME issue. My gut tells me it has to be something else, but I thought I’d ask here to see if anyone could point me in any other direction. I was thinking of swapping the crank sensor just to rule it out but have no codes for this.
Any help or feedback is appreciated.
Hoping someone here can provide some insight with my situation.
I purchased a 2007 S550 with bad motor (balance shaft). I found a replacement motor from a 2008 S550 with low miles. I put the motor in and the car fired right up and motor is healthy. Cleared codes and turned it off. Buttoned everything up and started the car again with hopes of test driving. A few seconds later, CEL came on and engine started misfiring. Scanned and had misfire codes for cylinders 7 and 8 (P0307 and P0308). Checked spark plugs and they look new. Checked coils and they looked good, but performed swaps anyway. Codes did not follow. Tested injectors and no issues.
Pulled a coil from the old motor and put a spark plug in it and grounded it. Attached to cylinder 6 first and had spark. Attached to cylinders 7 and 8 and had no spark. Now narrowed down to harness or DME thinking there is no signal reaching the coils. Checked continuity on the wires from DME to the coils and had continuity.
So this leads me to believe this is a DME issue. My gut tells me it has to be something else, but I thought I’d ask here to see if anyone could point me in any other direction. I was thinking of swapping the crank sensor just to rule it out but have no codes for this.
Any help or feedback is appreciated.
08-24-2020, 10:02 PM
#2
Super Member
First, I can tell you are a BMW guy. We call it the ME instead of the DME. Second, it looks like you have done the normal swapping and replacing of coil/spark plug/injector. The next step would be to test your compression and also a cylinder down test. Or you can go for it and install a new or used ME. If you need help getting a used module programmed to your car send me a PM. I have a shop in Houston and specialize on Mercedes Benz vehicles.
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vrracr (08-24-2020)
