Well, it's been an interesting couple of months with my car...
just passing 150K, replacing coil packs that are only 3K miles old, and another thats only
30K miles old....Getting a ABS error, then having the whole car mysteriously die while
trying to read the error code (1st the instrument panel died, then the whole car), then coming back to life.
My mechanic was able to determine the right rear wheel sensor was causing the error,
got the wheel sensor replaced and FINALLY get it passed for smog today, and my registration renewed.

My joy at passing smog didn't last long, as I got a P0302 error on the way home on a coil pack that was replaced less than 1000 miles ago.
Interestingly the replacing 2&3 coil packs 1K miles ago, the car ran great.
Could I be getting a bad batch of coil packs?

Well, I guess I can try the plugs... ?

I've seen people get errors from oil filling the chambers where the plugs are, but I haven't seen any oil.

I wonder about the connectors going to the Coil Packs....
anyone have any problems with the connectors?

Anyone else experience "extreme" misfires on an m111 engine?

Like I said, replacing coil packs seemed to have solved the problem.

What the hell is up?

 

wow...exactly my problems too! But...weird thing is...the CEL comes on for awhile because of Cylinder 3 misfire but then after about 2 engine starts and driving the car around for awhile...it goes away.

Mercedes told me i had to change the whole Head of the engine which will cost me $5000 bucks! Crazy...so i left and went to my mechanic and he pretty much says its my Cylinder 4 that is misfiring...

All this confusion....so I'm guessing i should change my coilpacks? Thing is...my mechanic has this tool that checks for the coils and shows that all 4 are working fine...so now im back to....really....do i have to change the whole head for 5K?!?!

They need a recall on this dammit....

 

Todd - when last did your car see new plug wires or do the coil on plug rigs come with wires?

 

So, I talked with an MB mechanic buddy and learned some interesting things.
According to him;
NGK iridium spark plugs are great and better than Bosch but should be replaced every 25-30K. As they age, they put more strain on the coil packs causing them to fail!
Ah ha! I let my recent set go to 50K, and I've been replacing coil packs like mad the last
10K miles or so.
I had a set of NGK's that only had about 30K miles on them, and prior to talking to him decided to put those back in and then retest some of the
coil packs that I had replaced.
Well, I'm not misfiring any more, but it does seem like i have a little less power.
I think our engines like more spark, and a bigger gap.
The old plugs were easily .050" vs. the .039" gap stated in the owners manual.

I started the job without talking to him, only to find the plugs pretty well stuck in there holes, didn't want to turn. Oh man...that can be big trouble.
I got them to turn a little, and then dosed them with liquid wrench and let them sit.
BTW do this cold, or just slightly warm on an aluminum head!

Meanwhile I paged my buddy...

He called and said the following.

1. Liquid wrench is ok.
2. Don't force the plug out, you'll have big problems.
3. Let is soak for a while, and if necessary, turn it out a little then back in to help the
LW to get into the threads.
4. Don't use the crap they give you for putting in spark plugs in the spark plug change kit the anti-seize stuff, and/or assembly lube.
It will cook, turn into a glue like substance and stick worse than the nothing.
He stated the best thing to use, is.....
Tranny fluid. Yup, put a drop of tranny fluid on the threads and then screw it in.
It doesn't have to be expensive MB stuff, just any old cheap stuff from the local auto parts store.
He said he also uses just a dab of the anti-seize stuff, but stated the guy who trained him on MB
said not to use it all!

So, I put the 30K plugs in and no more misfires.
But I'm going to go ahead and order new plugs anyway.

I haven't tested all the other coil packs I've had to replace lately, but
according to him, once they've been stressed they're no good.
But then again, I'm not getting a misfire on cyl 3 now, so hmmmmm.....
of course, just because it doesn't throw a CEL doesn't mean it's not misfiring,
it's just not misfing enough to cause a CEL.

The ECU actually counts the misfires and once it reach a magic number, like 20 out of every 600, that when it throws the code and shuts of the fuel to the cyl.
and you're stuck on 3 cyl. till you can pull off, shut down and restart,
and take it easy on the throttle till you can resolve it.

My slight loss of power might just be a function of
the timing pulling back from something thats happening below the magic number.