Mercedes GLC problems with misfiring for some time now

Hey, I had a similar problem with my 2018 Mercedes GLC. I only know a little about cars, but maybe I can help you. In my case, it was the Mercedes C-Class, model year 2016. The symptoms were almost identical: black smoke, engine indicator light, loss of power and so on. After a few examinations in the workshop, the diagnosis was clear: the engine control unit was faulty. This cost me around 1000 euros to repair. The workshop replaced the control unit and the car ran perfectly again after the repair. If you need more details, please give me more information about your vehicle, such as the mileage and whether you have read out any error messages. Hope that helps you! LG,

(Translated from German)

Hey, thanks for your contribution! My GLC currently has 96,543 km on the clock. I'll have the mileage and error messages checked more closely. It certainly sounds like a visit to the garage is unavoidable. Do you have any tips on what I should pay particular attention to during the repair? LG,

(Translated from German)

Hey, no problem, you're welcome. At 96,543 km, there could really be a number of things to consider. The tip about the engine control unit was relevant in my case, but there are a few other things you might want to have checked: 1. ** Spark plugs and ignition coils:** Regarding your original assumption - defective ignition coils or spark plugs could also cause these symptoms. If you have the opportunity, have them checked and replaced if necessary. 2. mass air flow sensor (LMM):** A defective LMM can also cause many problems, such as loss of power, black smoke and poor fuel economy. Should also be on your garage's checklist. 3 **Fuel system:** Check the fuel filter and fuel pump. If the filter is clogged or the pump is damaged, it can lead to all the problems you mentioned. 4 **Exhaust system:** A clogged or faulty catalytic converter could explain the black smoke and loss of power. Just have it checked. Another tip: Always ask the garage to show you and explain all the error messages read out. This gives you more transparency and you know exactly what is being done. Good luck with the repair! Hope your GLC runs smoothly again soon. LG,

(Translated from German)

Hey, thanks for your detailed reply and the tips! I will address the points mentioned at the workshop and make sure that everything is checked thoroughly. I also suspected the spark plugs and ignition coils, so I'm glad you confirmed that again. I'll also look at the other things you mentioned, such as the mass air flow sensor and the fuel system. I won't ignore the exhaust system either, as everything should be checked thoroughly. I find your advice to have all error messages shown and explained particularly helpful. This will give me a better feeling of what is actually being done and whether it is really necessary. Thanks again for your help! I hope my GLC will soon be fit again. LG,

(Translated from German)

Hi guys I have the following problem with my glc 2017 year petrol engine . A jerk when starting you are shaken ... when you put in R then more ... after starting the engine a few times it is gone ! Had once noticed that a ceramic part piece was gone . ... was replaced but this problem reappears after a few weeks ... am at a loss for the moment, do you have any ideas?

(Translated from German)

Hello, I assume you have a gasoline engine and not a diesel, right? What exactly do you mean by the ceramic part? Are you talking about the ceramic spark plugs? If a part has fallen into the engine, this could have caused considerable damage.

(Translated from German)

Yes, I mean the ceramic insulation on the spark plug. Some mechanics also said that it doesn't matter. As soon as I put new ones in there I get misfiring again after a few weeks ... these are the symptoms I meant , but I'm looking for the reason why this happens ... Today I had the shaking all the time ... didn't take any gas properly .

(Translated from German)

Good morning, I have a GLC 2017 gasoline and the engine diagnostic light comes on, I have taken it twice and they have updated the software, they say they have to change the thermostat or water pump, the car goes well and the temperature that indicates is the correct one, does it make sense what they indicate????

(Translated from Spanish)

Hello JuanLopez, If your engine diagnostic light is on, it's important to address it. Even though your car seems to be running fine and the temperature is correct, the light indicates that the car's computer has detected a problem. The thermostat and water pump are crucial components of your car's cooling system. If either of these parts is failing, it could lead to overheating, which can cause severe engine damage. However, if you're not experiencing any overheating issues, it might be worth getting a second opinion. Ask the mechanic to show you the error codes and explain why they believe the thermostat or water pump needs to be replaced. Remember, it's always better to be safe than sorry when it comes to potential engine problems. Please keep us updated on your progress.