Hi Scotty, Gotta 2000 Mercedes SLK 230 169,000 miles. I was changing the valve cover gaskets on my SLK. However, when changing the spark plug gasket I did not realize I had incorrectly placed the new spark plug gasket. I did not realize part of the metal from the original gasket was still on the valve cover. I put everything back on my car and started it for a few seconds. It had constant misfires, fuel smell, and running rough. I turned it off.
I then immediately took out the valve cover again. Then seated all the gaskets properly this time, but after putting the valve cover back on with all the hoses and wires, I started the car and it’s misfiring again. The car was running perfectly fine before all this happened.
So then I decided to try changing all the spark plugs, but that didn’t work.
I am getting codes for multiple misfires happening only in Cylinders 2 & 3.
My mechanic says to try swapping my coils to see if the misfire moves, but I am worried if I damaged my engine by starting it with spark plugs gaskets improperly place. Need help because my car had no issues before this?
Also I think my coils are still the original. A friend of mine says he’s had experiences removing coils to work on an engine and they suddenly go bad out of nowhere, not sure if this is true though.
This was my first time attempting to do this job, but now I’m sorta regretting it.
Make sure the harnesses are in the proper position. It sounds like you have them out if order. If 2 and 3 are missing switch those wire harness around and see what happens. As for the gaskets. Never use cheap gaskets or something from auto parts store they never seat properly. Order them from a German car site. Alot of times they resell actually OEM parts.
The sealing gaskets that come with spark plugs are attached to them. What do you mean by "incorrectly placed the spark plug gasket?" Do you mean the round gaskets that fit in the valve cover where the spark plugs go through the valve cover?
Basically on my old valve cover there were 4 rubber gaskets. I removed one of them. Then tried putting a new one in. I didn’t realize part of the old gasket was still in place. I had a hard time fitting the new gasket it. It wouldn’t fully stick in.
I went to an autozone asking why the gasket they gave me don’t fit. The guy pointed out that I didn’t completely remove the old gasket even though it looks like it’s removed.
Basically I tried to start the car with a valve cover gasket not fully seated properly. I then fixed my mistake, but unfortunately my car is having these new symptoms.
Swap the coils. It could be them, like your friend suggested.
Also, see here for further diagnosis -
https://carkiller.com/scottykilmer/qa/misfire-4/
So I finally figured out the problem. Turned out to be the wiring harness was really old and corroded. So I guess when I returned the coils, I did not realize the wiring was slightly off causing a misfire. My friend said it was called a pigtail wire. I was able to put the wire back so the connection was proper, the car was able to drive perfectly fine, but replacing the wire would be the best fix so it does not slip out. I ended up also just changing the coils anyway since they were the original Mercedes coils that were over 20 years old. Thanks for the all help and suggestions!
I’m glad the fix was just the pigtail connector. Thanks for posting back with the fix.
I love a happy ending.
@doc don’t we all..?