Few questions about new purchase....2004 S600
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Joined: Apr 2011
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From: 10 Sec infront of you.
2003 Mercedes S600, 2001 Mercedes CLK55 AMG, 2010 Mercedes GL450
Few questions about new purchase....2004 S600
Hey guys, I have been here for a while but did not post much. I currently have a 2009 GL450 for the family a 2001 CLK55 AMG which is for sale and I just picked up a 2004 S600.
I have done a lot of searching and have come to my conclusion that it is more then likely the coil but wanted to get some of your input in case I missing something because I don't want to replace the coil if I do not need to!
Car runs like **** but idles ok but if you give it any more then like 30% throttle it misses like crazy and has no power. Engine light is on and shows codes of cylinder misfire 7 and 9 and multiple cylinder misfire.... Anything I can do to verify that it is in fact the coil or if there is anything else I should check?
Thanks for any help!
I have done a lot of searching and have come to my conclusion that it is more then likely the coil but wanted to get some of your input in case I missing something because I don't want to replace the coil if I do not need to!
Car runs like **** but idles ok but if you give it any more then like 30% throttle it misses like crazy and has no power. Engine light is on and shows codes of cylinder misfire 7 and 9 and multiple cylinder misfire.... Anything I can do to verify that it is in fact the coil or if there is anything else I should check?
Thanks for any help!
MBWorld Fanatic!
Joined: Nov 2010
Posts: 2,605
Likes: 343
From: Welwyn, Herts, UK
2006 S600
Good choice, and good luck. It will be a challenge, but a rewarding one.
The first culprits to look at include the intake pressure and temperature sensors, and the O2 sensors. They're quick, cheap and easy to replace, and have caused lots of mysterious misfires.
Also worth checking are the spark plugs. There are 24, and its a long job, but often overlooked. Only need changing every 50/60k miles, but responsible for many misfires. The gap MUST be set to 0.7mm, not 1.0mm. Some plugs come with the wrong gap, and instructions not to re-gap them.
Can you read the part numbers of the actual coil packs fitted - you can just see them at the rear? New coil packs are better than old coil packs.
Ultimately it could be the coil pack, but the ignition power supply / control unit could also be the culprit (it's in the middle of the V, at the front).
Even if it is the coil pack, you can repair them now, rather than just replace.
If you do take a coil pack out, be VERY careful. Everything under-hood that is rubber or plastic is baked brittle and easy to damage.
Strongly recommend you get a Chinese clone MB Star Diagnostic System.
Strongly recommend you read this thread by Howard:
https://mbworld.org/forums/s-class-w...2003-s600.html
Lots of help here.
Nick
The first culprits to look at include the intake pressure and temperature sensors, and the O2 sensors. They're quick, cheap and easy to replace, and have caused lots of mysterious misfires.
Also worth checking are the spark plugs. There are 24, and its a long job, but often overlooked. Only need changing every 50/60k miles, but responsible for many misfires. The gap MUST be set to 0.7mm, not 1.0mm. Some plugs come with the wrong gap, and instructions not to re-gap them.
Can you read the part numbers of the actual coil packs fitted - you can just see them at the rear? New coil packs are better than old coil packs.
Ultimately it could be the coil pack, but the ignition power supply / control unit could also be the culprit (it's in the middle of the V, at the front).
Even if it is the coil pack, you can repair them now, rather than just replace.
If you do take a coil pack out, be VERY careful. Everything under-hood that is rubber or plastic is baked brittle and easy to damage.
Strongly recommend you get a Chinese clone MB Star Diagnostic System.
Strongly recommend you read this thread by Howard:
https://mbworld.org/forums/s-class-w...2003-s600.html
Lots of help here.
Nick
Thread Starter
Newbie
Joined: Apr 2011
Posts: 12
Likes: 1
From: 10 Sec infront of you.
2003 Mercedes S600, 2001 Mercedes CLK55 AMG, 2010 Mercedes GL450
Thanks Nick! I will check those sensors. There is no current 02 code but there was a couple stored 02 codes. But when I erased the stored codes they never came back.
MBWorld Fanatic!
Joined: Nov 2010
Posts: 2,605
Likes: 343
From: Welwyn, Herts, UK
2006 S600
The 02 sensors degrade gradually and react more slowly with age. When the engine is cruising, the mixture is adjusted up and down about stoichiometric several times per second. The mixture is controlled by a negative feedback loop using the primary O2 sensors (upstream, above the cat, and difficult to access). The operation of the primary sensors is monitored by the secondary sensors (downstream, in the cat, and easy to access), and these flag mixture faults where necessary.
However, this operation can be assessed qualitatively by using a PC or tablet based OBD2 monitor, which will show whether the O2 sensors are tracking the mixture variation quickly enough. A lack of wide, rapid swings in the O2 level while cruising indicates a tired sensor. Alternatively simply fit new ones. No need to buy expensive ones.
Nick
However, this operation can be assessed qualitatively by using a PC or tablet based OBD2 monitor, which will show whether the O2 sensors are tracking the mixture variation quickly enough. A lack of wide, rapid swings in the O2 level while cruising indicates a tired sensor. Alternatively simply fit new ones. No need to buy expensive ones.
Nick
Senior Member
Joined: Aug 2014
Posts: 370
Likes: 31
S55 AMG
The ignition module, if it goes bad, should cause all the cylinders in one bank to misfire, not only a couple. At least for me, this was the case, I did not need to change the coil pack at all and it started working again when i changed the ignition module. If only a few of your cylinders are misfiring, i would check the spark plugs. I also had an issue where a few cylinders would misfire upon harsh acceleration, but that was fixed by replacing all 24 spark plugs. Dealing with this car's misfires can be annoying, but very rewarding at the end 
Good luck.
Good luck.
