2006 C230 intermittent misfires cylinder 3

[2006C230]

Hi. I have a 2006 C230 that is acting a little crazy. A few weeks ago the car would not start. Then it started but would not go in to gear. Left it over night and everything worked great the next day. Now I am getting intermittent misfires of cylinder 3 and very rarely cylinder 6. Sometimes I can start it and it will run perfectly fine then all of the sudden cylinder 3 will misfire and the check engine light will flash. Shut it off and restart it, it will work fine for awhile. When it's missing I can reset the codes and it will run fine for a little while. Stored codes are 303 and 353. Checked the coil wiring and it's OK. I have a launch CRP123 and it will sometimes not be able to connect in OBD2 mode, it says failed communication. It mostly connects in the vehicle specific mode. Seems like it's a ecm problem. Is there any way to confirm that the ecm is bad?

 

[Uncle Benz]

I would try swapping the number 3 cylinder coil with cylinder 1. See if the fault moves. If it does the coil pack is bad

 

[2006C230]

Already replaced coil. Code 0353 says primary side control for coil #3 open. So it's not the coil. Doing a reset of the codes makes the miss go away and the engine runs smoothly until you drive it.

 

[Uncle Benz]

Test the wiring then between the coil and the ecu. If the wiring checks out it sounds like the driver has gone inside the ecu

 

[2006C230]

Checked the wiring and resistances for coil 1 and 3 were the same. After that I changed the pcm and that didn't fix it. Thinking it may be a broken wire or bad contacts.