200 7 CLK 350 cylinder three misfire
Thread Starter
Super Member
Joined: Mar 2012
Posts: 535
Likes: 13
From: Franklin, MA
2006 CLK 350/. 2009 CLK 350/2005 Both White
200 7 CLK 350 cylinder three misfire
So I’m pretty good with these cars. I used to be mechanic when I was in my 20s working on a lot of German cars. I mean put it this way I’ve done intake manifold swamps within an hour and a half. So here’s my problem. Start the car this morning. Go to give it gas gave it a few seconds to run through a check engine light.
Started to drive I said what the hell I gotta reset till no big deal I pull over I try to reset it try to reset it try to reset it absolutely no good that’s a first
Then I head home and I said what the hell let me just swap out the coil pack since I have spares. Swapped out the coil pack and reset seems to be perfect. Check engine light is gone. Drove to work 25 miles away. Then I left work today at 4 o’clock. Started it up immediately in the parking garage. I got a check engine light. Try to reset it three times no way drove all the way home and I swapped out the coil pack no help so I removed the spark plug and I looked closer three times and I noticed the tip was gone. We’re talking about the electrode that comes out of the middle of the spark plug. I was hoping to see something worn, but it was gone. I then replaced a spark plug start the car still misfire.
so the next thing I did was run a compression fitting 130 dry 150 wet
I put a screwdriver against the injector and you can hear it clicking so it’s getting power
So I also checked that the coil pack was shooting a spark to the spark plug because I removed it and grounded it so the coil packs are getting electricity I guess it has to be the fuel injector that’s clogged correct or am I missing something. I did order eight of them. They’ll be here Thursday.
If there’s anything else I may be missing, please let me know
Started to drive I said what the hell I gotta reset till no big deal I pull over I try to reset it try to reset it try to reset it absolutely no good that’s a first
Then I head home and I said what the hell let me just swap out the coil pack since I have spares. Swapped out the coil pack and reset seems to be perfect. Check engine light is gone. Drove to work 25 miles away. Then I left work today at 4 o’clock. Started it up immediately in the parking garage. I got a check engine light. Try to reset it three times no way drove all the way home and I swapped out the coil pack no help so I removed the spark plug and I looked closer three times and I noticed the tip was gone. We’re talking about the electrode that comes out of the middle of the spark plug. I was hoping to see something worn, but it was gone. I then replaced a spark plug start the car still misfire.
so the next thing I did was run a compression fitting 130 dry 150 wet
I put a screwdriver against the injector and you can hear it clicking so it’s getting power
So I also checked that the coil pack was shooting a spark to the spark plug because I removed it and grounded it so the coil packs are getting electricity I guess it has to be the fuel injector that’s clogged correct or am I missing something. I did order eight of them. They’ll be here Thursday.
If there’s anything else I may be missing, please let me know
Thread Starter
Super Member
Joined: Mar 2012
Posts: 535
Likes: 13
From: Franklin, MA
2006 CLK 350/. 2009 CLK 350/2005 Both White
Wow, this is scary. I actually stumped people in two Mercedes-Benz forums where I’m not getting one reply that is pretty concerning. I find it amazing that no one has a opinion or idea.
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Joined: Jun 2024
Posts: 191
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E320
It sounds like you've been through quite the troubleshooting gauntlet with your 2007 CLK 350! Misfires can be a real pain in the neck, especially when you've already replaced the spark plugs and coil packs. If you're suspecting a fuel injector issue, you're likely on the right track. Sometimes, an injector can get clogged or fail to open properly, which can lead to a misfire on a specific cylinder.
Since you've already run a compression test, that rules out any serious mechanical issues, but I’d recommend checking the fuel delivery to that cylinder as well. If you have access to a scanner, Youcanic scanner is very good at this, it might be worth looking at the fuel trim readings and injector pulse width to see if anything looks off. If the injector is indeed the culprit, cleaning or replacing it might just solve your problem. Good luck, and keep us posted on what you find!
Since you've already run a compression test, that rules out any serious mechanical issues, but I’d recommend checking the fuel delivery to that cylinder as well. If you have access to a scanner, Youcanic scanner is very good at this, it might be worth looking at the fuel trim readings and injector pulse width to see if anything looks off. If the injector is indeed the culprit, cleaning or replacing it might just solve your problem. Good luck, and keep us posted on what you find!
Thread Starter
Super Member
Joined: Mar 2012
Posts: 535
Likes: 13
From: Franklin, MA
2006 CLK 350/. 2009 CLK 350/2005 Both White
So here’s the update we got some good results apparently. So I took no good fuel injector one and put it to three. I purchased some new injectors today I put the new one where one was and I started up the car and immediately I got misfire cylinder 2 well that’s an improvement from three. Then I swapped one from chill and it jumped to one OK great then I swapped four to one and I got four. What’s funny is I had two spare coil packs and I kept on getting an error.
these coil packs were a scenario where I did a switch and suddenly it started working so I didn’t wanna throw them out. I ordered two more starting brand new fresh with new ones no more used crap. They should be arriving from Amazon. I’ve had good luck with the Amazon ones for 19 bucks. I’ll update tomorrow.
But the good news is it moved. PS fuel injectors very easy to replace the only problem. Is that damn clip lining it up. I might replace the other five in a couple of weeks when it gets warmer out. I have new ones I might as well use them. The reason I didn’t put them all in was in fear of an aftermarket error or something to that effect.
these coil packs were a scenario where I did a switch and suddenly it started working so I didn’t wanna throw them out. I ordered two more starting brand new fresh with new ones no more used crap. They should be arriving from Amazon. I’ve had good luck with the Amazon ones for 19 bucks. I’ll update tomorrow.
But the good news is it moved. PS fuel injectors very easy to replace the only problem. Is that damn clip lining it up. I might replace the other five in a couple of weeks when it gets warmer out. I have new ones I might as well use them. The reason I didn’t put them all in was in fear of an aftermarket error or something to that effect.
Thread Starter
Super Member
Joined: Mar 2012
Posts: 535
Likes: 13
From: Franklin, MA
2006 CLK 350/. 2009 CLK 350/2005 Both White
Also feed it out of my own as normal turned out the fuel injector and cylinder three was bad along with coil pack. I think the defective coil burned out the center electrode possibly. Once I replace the coil pack with a $18 Amazon special, which are pretty good And a fuel injector from Amazon $46 for eight I only needed. The car is running perfect.
Thread Starter
Super Member
Joined: Mar 2012
Posts: 535
Likes: 13
From: Franklin, MA
2006 CLK 350/. 2009 CLK 350/2005 Both White
Well, I figured it out finally and it was driving me nuts there seems to be a connection issue on cylinder three I put some dielectric grease after resetting the car from the check engine light scenario several times swapping coil packs and spark plugs. I said let me disconnect this connection to the Fuel injector. Put some dialect grease push up the white lock locking correct clip. Then I pushed it down lock the clip best I could there’s a harness that’s right near there that I kinda adjusted so it would be pushing down on the connection into the injector and the car is running great. . So what I think I’m gonna do is I’m gonna revisit it and I’m gonna put some type of epoxy that will fuse the connector to the injector once and for all.
