Hey, I have a W204 Mercedes-Benz C-200 Kompressor. My car tends to misfire after 2-2.5 hours of driving. There are no issues in starting up the car and it drives very smoothly until the misfire begins. It starts vibrating violently and the engine makes the missing noise. Pick up also gets hindered. In many cases turning off the vehicle for 10-15 mins and restarting solves the issue until the misfire starts again. The workshop told me its bad gas and that the filter is getting clogged, however I refilled with a full tank of high octane petrol but the misfire hasn't disappeared completely.
- Recently changed 02 Sensor
- Recently Changed spark plugs ]
- Recently Changed Fuel Pump

Ps. The engine malfunction lamp is also turned on .

 

I do not see the ignition coil replacement, should have done with spark plugs.

 

Does that mean I need an ignition coil replacement now ? also how does it cause it to misfire after every 2 hours

 

Odd...

If it was plugs that were developing hot spots then causing pre-ignition, it wouldn't take 2 hours
If it was junk in the fuel, it would have to be something you'd see if you siphoned out some of your fuel, especially from the bottom of the tank. Have you siphoned a couple gallons of your fuel to see if there is something in it? Something small enough that it takes 2 hours to build-up around the filter sock?

 

If the check engine light (CEL) is on, there should be diagnostic trouble codes (DTCs) stored. The codes should give an indication of what the actual problem is.

 

definitely get the OBD port scanned. You won't go very far without listening to what the ECU has to say.

Treat this as urgent, you don't want to damage your catalytic converter with extreme heat.

The way this happens only on long drives after 2hrs drive makes it likely a type of soft-crash. Good chance low voltage is involved in helping all that happen.

Scan your car, we'll learn more... (Beware of limp-modes, keep out of the fast lane).

 

hey @CaliBenzDriver thanks for the response. Was out of town and drove nearly 250km or 5 hours continuously. The car didn't misfire even once, I was driving on the highway at high speeds and acceleration.

however sometimes times when I push the accelerator all the way down / hard accelerate. It will start misfiring. Once the engine is turned off and then on the issue is resolved. I will be getting the car scanned tomorrow.

 

So to summarize your above experience:

• engine ran long trip without misfire
• except during WOT accelerations
• that was resolved by restarting car

Hopefully the OBD scan will bring additional clues to point at specific modules soft-crashing.

This is an interesting case with a common set of issues. We'll see where computers make it go....
✌️

 

hey @CaliBenzDriver sorry for the late update to everyone out here, got caught up with work. Finally got the car scanned 2 weeks ago at the workshop.

issues were :
2 failed fuel injectors

the problem has been resolved now and the check engine light has disappeared and hasn't returned ever since. WOT is good, no misfires, good pickup.
I suggest everyone with a c200 kompressor or any Merc petrol to not drive on critically low fuel levels frequently.
If there is any one with a Merc that lives in the Mumbai area I would strongly recommend getting your car jobs done at FG Automobiles ( Farhan Kunni ). A very good service experience and knowledgeable mechanics. He put my car right !