2010 E550 rough idle CEL.
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2010 E550
2010 E550 rough idle CEL.
Hey everyone,
I was driving home today and was sitting at a light and my car just started idling really rough. As I started driving I noticed it was rough until I got to second gear or so and it would go away. Once I got to another light it was idling rough again. And like before it was rough and sluggish until second or so gear. My CEL was flashing on and off so I pulled over. I puked some codes and got cylinde 3 and 4 misfiring. I got some help and we noticed that wiring underneath the hood was a little burnt/corroded. I’m not sure exactly what the wiring was but if it was on the right side on top of the engine. We taped that up with electrical tape and I took it for a spin and it seemed ok After driving for a few minutes it came back. Anyone have any ideas?
I have noticed over the last few days at start up it’s a little more rough.
I was driving home today and was sitting at a light and my car just started idling really rough. As I started driving I noticed it was rough until I got to second gear or so and it would go away. Once I got to another light it was idling rough again. And like before it was rough and sluggish until second or so gear. My CEL was flashing on and off so I pulled over. I puked some codes and got cylinde 3 and 4 misfiring. I got some help and we noticed that wiring underneath the hood was a little burnt/corroded. I’m not sure exactly what the wiring was but if it was on the right side on top of the engine. We taped that up with electrical tape and I took it for a spin and it seemed ok After driving for a few minutes it came back. Anyone have any ideas?
I have noticed over the last few days at start up it’s a little more rough.
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Joined: Oct 2010
Posts: 5,142
Likes: 1,295
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Hey everyone,
I was driving home today and was sitting at a light and my car just started idling really rough. As I started driving I noticed it was rough until I got to second gear or so and it would go away. Once I got to another light it was idling rough again. And like before it was rough and sluggish until second or so gear. My CEL was flashing on and off so I pulled over. I puked some codes and got cylinde 3 and 4 misfiring. I got some help and we noticed that wiring underneath the hood was a little burnt/corroded. I’m not sure exactly what the wiring was but if it was on the right side on top of the engine. We taped that up with electrical tape and I took it for a spin and it seemed ok After driving for a few minutes it came back. Anyone have any ideas?
I have noticed over the last few days at start up it’s a little more rough.
https://youtu.be/qYPGkGM_py4
I was driving home today and was sitting at a light and my car just started idling really rough. As I started driving I noticed it was rough until I got to second gear or so and it would go away. Once I got to another light it was idling rough again. And like before it was rough and sluggish until second or so gear. My CEL was flashing on and off so I pulled over. I puked some codes and got cylinde 3 and 4 misfiring. I got some help and we noticed that wiring underneath the hood was a little burnt/corroded. I’m not sure exactly what the wiring was but if it was on the right side on top of the engine. We taped that up with electrical tape and I took it for a spin and it seemed ok After driving for a few minutes it came back. Anyone have any ideas?
I have noticed over the last few days at start up it’s a little more rough.
https://youtu.be/qYPGkGM_py4
The wiring there here has a good chance to be either ignition coil or fuel injector wiring so any short on those certainly can be reason for trouble. Make sure this burned wiring is repaired correctly.
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2010 E550
They said the wiring was good and that wasn’t the issue. They replaced the spark plugs and the battery and still can’t get it to crank. They can’t pull any codes, and are looking at the wire again.
They called me back and they aren’t sure what the issue is. They can get it to start but it is misfiring on almost all cylinders now.
They called me back and they aren’t sure what the issue is. They can get it to start but it is misfiring on almost all cylinders now.
Last edited by wrinkles88; Dec 12, 2019 at 09:30 PM.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,142
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
They said the wiring was good and that wasn’t the issue. They replaced the spark plugs and the battery and still can’t get it to crank. They can’t pull any codes, and are looking at the wire again.
They called me back and they aren’t sure what the issue is. They can get it to start but it is misfiring on almost all cylinders now.
They called me back and they aren’t sure what the issue is. They can get it to start but it is misfiring on almost all cylinders now.
I would look look at the crank shaft position sensor as that is vital for correct spark timing.
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2010 E550
I did suggest maybe something with the fuel and they said they will look in to that as well.
I had my crank shaft sensor replaced about 18 months ago. It was always causing me issues. I had to replace my o2 sensors twice because of it. I will suggest this to them anyways.
I had my crank shaft sensor replaced about 18 months ago. It was always causing me issues. I had to replace my o2 sensors twice because of it. I will suggest this to them anyways.
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2010 E550
I got my car towed to a Mercedes dealership to see if they can diagnose it. They still haven’t figured it out. They asked if I had my o2 sensors replaced which I did 18 months ago. I have asked them to them to check the coils and coolant temp sensor which they will do tomorrow.
I don’t think they have any idea at the moment.
edit. They found a bad wire connection for the o2 sensors and replaced that but it is still misfiring. They said it’s only one said of the engine bank that is misfiring and if I believe they said it was the drivers side.
Anyone have any ideas?
I don’t think they have any idea at the moment.
edit. They found a bad wire connection for the o2 sensors and replaced that but it is still misfiring. They said it’s only one said of the engine bank that is misfiring and if I believe they said it was the drivers side.
Anyone have any ideas?
Last edited by wrinkles88; Dec 19, 2019 at 06:14 PM.
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From: Savannah, GA
2010 W212 E550 4matic
If you're over 100k miles on the original coils and/or plugs just replace them. It's cheap and the results are immediate. A diag job is 100 to 175$, the kit is 200 something.
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Thread Starter
Junior Member
Joined: Jul 2014
Posts: 58
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2010 E550
Just a quick update and a few more questions.
In the end they replaced they o2 wire and o2 sensor. This is the second (possibly 3rd) replacing the sensor so there is definitely something else going on.
Now at startup my car is a little rough still. I don't know if other people would notice but I do. It seems it’s at about 1000rpms when I start then comes down with in 3-4 minutes. For the first 20 minutes or so it seems a little rough at stop lights or idle and once I start driving it goes away. Any idea what could be causing that?
In the end they replaced they o2 wire and o2 sensor. This is the second (possibly 3rd) replacing the sensor so there is definitely something else going on.
Now at startup my car is a little rough still. I don't know if other people would notice but I do. It seems it’s at about 1000rpms when I start then comes down with in 3-4 minutes. For the first 20 minutes or so it seems a little rough at stop lights or idle and once I start driving it goes away. Any idea what could be causing that?
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2011 E350
3rd O2 sensor
If you have an infared thermometer check your precast temp and compare it to post cat. I would also recommend checking ground points. If you can check the resistance from the coil pack negative pin to engine ground, if it’s over a half ohm you have a ground issue.
