04 E55 AMG: Replace plug wires

[kevm14]

This was easy. It's just that there are 16 of them. I did spring for the special offset 17mm wrench to pry the boots off the plugs but maybe because the previous owner did plugs during his ownership, they were not that stuck. I did use the tool but it was pretty effortless. I was expecting a fight or something. Pushing them on and getting them to lock on the plug took some force and care but nothing really special about this job.

The high end NGK wires I bought are labeled with the cylinder number and A or B position. B position is for Back plug or Bottom connector of coil. Pretty fool proof though the cylinder number layout is strange from what I am used to.

Approximate steps:
- Remove front engine cover
- Remove air intake snorkles
- Remove air filters and intake (a unit)
- I found that I could disconnect the wires from the coils and then remove the coil and flop it up out of the way.
- Then I pried off each wire and matched it up with the right replacement
- Go down the bank just like that

I checked the torque on the valve cover bolts and found a breather bolt at the rear driver's side valve cover was a bit loose.

Once all the wires are replaced, flop the coils down one by one, screw them on the valve cover and snap the wires back on the coil. I torqued the coils to like 6 lb-ft or something like that.

I did use a little silicone grease at the tip of the plug wire where it attaches to the plug. Not sure that does anything. The wire set came with a small pack which was barely enough for 16...

I do believe these were the original Bosch plug wires, probably original to the car. The forum claims they wear out somehow and can cause a cold idle shake which my car does. It seems reduced but not eliminated. Test drive revealed everything was good. Probably not worth spending $250 on this particular item at this particular time but now it's done. I could check the resistance on the old wires I guess. Supposedly they go out of spec and the ignition system doesn't work right.

Here are some pics.

[Adam]

This was easy. It's just that there are 16 of them.

It's like a double Ranger. With a supercharger. There are no other differences.

[kevm14]

I was chuckling periodically throughout the job because the ignition system layout is basically just like an LS. Coils bolted to valve covers, a short wire and the plug goes in the side of the head.

The good news, and I suppose this is a little surprising, these coils are actually reported to be really solid and are not known for failing. Mine may well be original. They are a pretty beefy coil especially if you compare to the size of like my Northstar coils.

[kevm14]

I think this job was a waste of time and money. I don't think there is any difference. It still does that cold start roughness (until you put it in gear). But if they were original I guess it was good to replace. Or something.