M272...350CGI misfire

[Henrik Pedersen]

Seeking help here at the champs...

My CLS350CGI just started to report misfire and coil faults on cylinder#3 (P 0303: Misfire cylinder three and P 0353: Primary/secondary coil)

So i swapped the coil with cyl.4, put new sparkplugs, and also swaped the ignition cable wit cyl 4, but the fault comes back...and still on #3

I have never had the fault after cold start, and never while driving. It only shows up at idle when the motor is very warm, or when i start the engine while it is warm.....

Any suggestions how to troubleshoot this pain...?

 

[bembo449]

so is it actually mis-firing ??

 

[malcolm E53 AMG]

I’d check the injectors for spray pattern and fuel delivery

 

[Henrik Pedersen]

When the problem is there after starting the engine, the engine is wobling, and the engine fault lamp comes on, and i get the misfire codes, it continues to run very uneven, untill i stop, and wait untill next day... but sometimes when i stop and restart it runs fine again. I gues that is because the fuel delivery is cut for thet cylinder, and only comes back after restart....

 

[Uncle Benz]

The code is specific to the ignition circuit, so leave the injectors alone for the minute. Have you correctly identified cylinder 3 on the engine? Swapping components around is a great way to test, but make sure you’ve actually moved cylinder 3. You can confirm cylinder numbers by unplugging one at a time and see what the ecu reports. If you have correctly identified 3 and swapped the plug, lead and coil around the next step is to thoroughly check the wiring between the ecu and the coil, and the earth wiring. If all that checks out, personally I’d have the ecu tested next.

 

[Henrik Pedersen]

so is it actually mis-firing ??

Hard to say, in the faulty state, the engine runs like on 5 cylinders, but i guess that i because it cuts the fuel to that cylinder, when it registers the misfire code.

 

[bembo449]

Right , if the fault doesn't move with a change of coil pack then that leaves witing to the coil pack , fueling issue Or possible valve problem id say

 

[Henrik Pedersen]

The code is specific to the ignition circuit, so leave the injectors alone for the minute. Have you correctly identified cylinder 3 on the engine? Swapping components around is a great way to test, but make sure you’ve actually moved cylinder 3. You can confirm cylinder numbers by unplugging one at a time and see what the ecu reports. If you have correctly identified 3 and swapped the plug, lead and coil around the next step is to thoroughly check the wiring between the ecu and the coil, and the earth wiring. If all that checks out, personally I’d have the ecu tested next.

Yes, i did that. Pulled the connector to the cylinder i thought was #3, and i got the same codes for cyl #3. Then i swapped the coil and the cord with cylinder 4, but the fault came back on cyl 3 at the next start. I have pulled and inspected all the plugs and connectors, also tried to heat up the ecu, knock a bit on it, and fiddle with the wires, while the engine was running, but unable to provoke the fault to show up.
I find it interesting that the fault inly shows up after startin a warm engine.

I am glad that none of you mentione a warnout timingchain or balancer-shaft-sprockett yet.
Next i guess is the ECU, but i believe it needs to pe reprogrammed to match chassis numbers and all?