E320 Missing and not getting any coil codes
 

EDIT:
I think I have it figured out. Bad wires. I haven't changed them yet because I just also figured out I believe the car has a bad head gasket. It white smokes when hot and driven hard.

But last night I decided to work on it for a second and noticed (it was a VERY dark night) while running that I could see arcing through the plug wires. It was faint but there were sparks through the insulation to the valve cover on all 3 wires (or at least two of the three). Also, the number 2 or 3 *the one with the plug wire can't remember* boot on the plug was easy to see that it was arcing to the valve cover whenever there was a mis. So......... seems like I've found the problem.

At this point I'm guessing the common failure of plug wires is the die-electric properties of the insulation. Maybe a ton of electrical tape would fix that! Of course the real fix is to just change the wires.

But on to bigger things. The head gasket!









I was thinking ignition (was getting a 22 and 23 code). I changed the spark plugs and boots below the coils. I used Bosch F8DC4 Copper Non Resistor plugs.

Now I'm still getting a mis on some cylinders but I'm only getting a

4 Hot film mass air flow sensor
13 O2S (Lambda) control system operating at rich or lean limit

I'm getting really confused by this thing.

I noticed if I let one of the vacuum hoses loose it will exaggerate the misfire.

I did a little EGR testing (ran a vac line direct to the EGR on and off and plugged the line when not on the EGR). It ran bad when connected to the EGR but It also seemed like the EGR itself has a leak I haven't Mighty-Vac tested it for holding vacuum but just sucking on the vac line I'm getting no resistance.

Can a vacuum leak cause a misfire?

This happened to me awhile back. Turned out to be the engine wire harness.

I notice some wire rot on the X28(?) connector the one that sends the starter it's signa.

I also notice that the tube going to the EGR and that little electrical vacuum block isn't giving much (if any) vacuum.

The last thing I checked is the diaphragm on the EGR itself. It will not hold vacuum with a vacuum tester. It doesn't hold ANY vacuum.

Should I try disconnecting the EGR pipe at the EGR and see if it improves? Maybe stuck open?

I cut open some of the wire harness and the two spots I saw (between the head and firewall) look good.

I had a problem with my 93 400 SEL missing. I found the EGR hose was broken and drove for a day without it and it made absolutely no difference. Mine missed under load and after changing plug , suppressors , caps n rotors we pulled the coils and saw one was white from arcing .

Changed it and all is well . Look up my profile to find my posts in my old thread to see if your problem is similar. Had 3 MB techs put scanner on it and it drew no codes although one coil was bad.

Do not believe what scanners do not tell you !

I will have to try a new coil or two. I am noticing quite a variance in the idle with a vacuum line allowed to leak. If I let it leak I notice it misses like crazy. When I put the line back the missing diminishes but it's still there. That makes me really wonder if there's a vacuum leak somewhere. I think I hear a leak around the throttle body area but I'm not sure. I do notice there's not much vacuum in the little electronic block at the front left side of the head.