albertseo1115

I noticed a sudden rattle on the engine from 1000-2000 RPM so I ran down to the auto shop and told me one cylinder is causing a misfire.

It did not happen again the next day but randomly happends after ignition of 50 miles of driving the next day.

The guy said, I should change the spark plug and one ignition coil. Did this happen to anyone? Should I only change the spark plug and see or should I change the ignition coil as well?

Its a 2015 E350 4Matics with 48000 miles.

ygmn

you should find out which cylinder is missing or is what is called a RANDOM misfire by asking for actual CODE

Check engine light on?

kajtek1

48k miles on original plugs?
When in doubt- change the plugs and then worry if the problems still exist.

CaliBenzDriver

I would let your auto shop figure this one out. You can be sure it's nothing major at this early stage.

Let that be a reminder that maintenance is to be done on schedule. Example: your transmission needs regular service to keep clutch material from accumulating over the valve screens.

Before changing any parts, the bad one should be located: injector, coil, boot, plug,... move things around to see if the misfire follows or stays and knock on wood.

​​​​​​​These cars need expert care like Rolex do. The real troubles start when still good OEM parts get replaced with no-name junk for no reason.

Happy Thanksgivings!
🦃

kajtek1

So does iPhone, or any android when you think about it.
Even WI-FI heating thermostat those days become rocket science.
Still digital cars are on the roads for 25 years and when I happen to have 1 in 1998,- what for many owners was a nightmare since mechanics were 10 years behind technology, different forum member created "forum wisdom" where lot of things can be done with $50 scanner.
So I disagree that spark plug change require expert.

Happy Thanksgiving

CaliBenzDriver

Kajtek you are right: it's not too difficult to swap plugs.

Often the hard part is to figure what's causing problem without replacing perfectly good OEM parts.

My DD is the king of lean misfirings. People keep replacing plugs + coils and again plugs + coils... but misfiring remains!
Some ppl blame it on Evil, others figure it's out of their wheelhouse. My engine fires nice and strong on original coils... software is detuning the timing.
🦃

oldmots

More than likely, you have a sticking injector. Run a can of BG44K or Techron fuel system cleaner through and see how it does. Way cheaper than replacing injectors or coils. I just went through the same thing on mine, the injector cleaner fixed it. It is best to run a bottle of cleaner through at every oil change.

2011WhiteE350

My 2011 has the same symptom.
It was misfire on cylinder 3 and I can feel the vibration inside the car.
I change the fuel injector. It was clogged up bad.
The misfire was gone but the vibration is still there..
Were you able to fix the vibration?

MBNUT1

I thought that most gasolines come with injector cleaner already added? I have a new bottle of Techron that I have never added for that reason.

Sunnyslope48

One thing to try, if you haven't already, is to fill your tank with premium fuel, highest octane at your filling station. Higher octane will keep the computer from pulling timing out of the engine After using the cheap fuel for a couple of years then getting a full tank of the good stuff, I was amazed at the difference in how the engine ran. My wife thought I was a GENIUS it ran so much better. Well, of course I am a genius. I filled the tank!

albertseo1115

I appreciate all the responses. I've been oversea for a month and just came back.

I changed all spark plugs and it seemed fine but engine light came on irregularly. I will try Techron fuel system cleaner this week to see if it improves. I always fill premium at Costco gas(only).

It was difficult to change the 5th 6th spark plug... so I let those two serviced at Mercedes..

oldmots

I have heard that premium fuel has additional additives, but I've never seen definitive proof of it. I run premium in my cars that require it and still get dirty injectors. Techron definitely does keep the misfires away. If it's bad, it could take two treatments. I have a car with direct injection and I have heard that they need fuel treatment more often. I treat the fuel at each oil change, it keeps the system clean and running smoothly.