I have just changed the wiring harness on my 300e, it was shot. New one went in easily. THe car is still running rough. Changed plugs, which uncovered the harness problem. Now I have switched coils and wires around and it seems that the cylinders for the second coil are not firing. DOes anyone know how to check the input side of the coils? I tried moving coils and the problem stayed indicating that the coils and wires are fine. Someone mentioned boots in a post, I moved them around also and the problem still remains on the same two cylinders. Any help would be appreciated.

Because the second coil [ T/2]is cyl 4 and also fires in series with cyl 3 ,
[ being adjacent cylinders],
..you may want to do a quick compression check for possible head gasket blow out between those two cylinders first...........

THanks for the Information, but I messed up some info. Its the first coil that is not firing which is for cyl 2 and 5 I guess. Until I saw your answer I didn't make the connection that I was thinking "the coil" sitting atop cyl 2.

Also, I have removed the spark plug wire from cyl 5 while engine is running, no difference, and no spark coming from wire.
jsb

First thing to do [you may have gotten this far] is to change both plugs and the connector under the coil...plus check the wire to 5 for continuity.
The spark from the coil completes a loop for two cylinders in series. Goes from the coil- connector- plug- block- plug- plug wire- coil.
Any break here in this chain and you get no spark.[ most common is plug connector under coils]. Common practise to change them w/plug change, regardless....
If you want to check for B+ , it will be at the coil primary input. It is constant 12V . , as the coils are a switched ground at the ECU [ switching transistors]

OK
Cancel my possible head gasket theory..Not adjacent cylinders with correct info.....[ T/1 instead of T/2]
See next post.

THanks for the info. I did do those things. I also checked the input side of the coil, which all 3 coils show as a constant 12v. I took the plug wire off a good firing cylinder (1) and checked it for spark (good) then did the same for 5 using the same good wire (no spark). i will change the boots on all the coils even though i think I have proven them OK by substituting one for another.
A question. Since I was having a sporadic missing problem and decided to change the plugs, it was due, then uncovered the bad harness issue, IS it possible that --- 1. THe harness could have damaged something. 2. The system is smart enough to shut down the cylinders associated with the number one coil, assuming that it was the one missing at the start and need to do something to allow it to work again. Also in my testing of the old harness, after removing it I traced the structure of the wires to each coil and they seem to be made up off 2 wires into each coil, 1 is a common which comes from a wire terminal block on the left wheel well, Is this the ground? and the other is a seperate wire for each coil originating in the large multiwire terminal connector. I assume this is the pulse side for firing order.

From the info you have givin, it is possible to now have a bad switching trans in the ECU for that coil. That is what completes the ground circuit ...it may be open from the bad harness shorting...
Scope testing...ecu replacement may be needed.

Did you/can you get the codes from pin#8 on diagnostic socket [HFM/SFI , ign/fi module] ????????????

I am going to build one of your handy code retrievers tomorrow. Just in case what would a ECU cost? any idea? thoughts -- new vs used.
Again thanks for your time.

Get the codes from 8 and go from there..
You may also just have a bad segment magnet on the flywheel,, but that should show on the codes
I am assuming that you have good, solid connections when you changed the harness..
also, do you have an inductive timing light???

I do have access to one.

Well, I built the tester today. THen based on what I saw looking for
a place to use it, and an old post I found that I have a 16 position
block.

I did the following:
1. Turned ignition key to on position.
2. plugged red lead into position 1.
plugged blk lead into position 16.
plugged other lead into position 8.
3. pressed and held momentary switch
for 3 one-thousand count (led light on)
4. released switch ( led light went off) and then
blinked 4 times.
5.repeated steps 3 and 4.
blinked 9 times.
6. repeated steps 3 and 4.
blinked 13 times.
7. repeated steps 3 and 4.
blinked 22 times.
8. repeated steps 3 and 4.
blinked 23 times.

At this point the sequence repeated itself.
WHat does it mean?

All help is very much appreciated.
thanks

You have given me a typo error or you have mis-wired the tool.
The bk is neg [goes to pin 1], rd is pos [pin 16]..
If not a typo, I suspect the reason you still got codes is that you have the led out of polarity [ backwards]
check it again..you do not want to be fooling with 12v down a code retrieve data line at all...........

Anyway , yiu have both coil/ignition and fuel metering codes, so you now want to clear all the codes from that module [ as they can be from previous faults before coil/connector repair.] and run the car for a day and recheck for most recent codes .
To clear, after each code , wait 2 sec, hold for 8sec , repeat after each code .. Turn off key for 10 sec, on for 10, start car.
If codes are clear , 1 flash will appear when new retrieve is attemped.

Advise me on the tool findings.

It was a typo. blk = 1; red = 16; other = 8
SInce the engine is running so rough ( 4 cylinders I think)
Could I just let it idle in the driveway to satisfy the "run for a day"
to pick up any faults.
Arthur: thank you for all your input.
jsb:

OK . I figged a typo , but wanted to make sure before we get in trouble here....

Only on four .. you now have an E220...[bg]

OK
Clear out the junk codes and as soon as you get a 1 flash on pin 8 , then push the button again for 8 secs, turn of key for 2 sec, on for 50 , and start.
This will reset/reactivate the module ...
See what you get after that.

Also go get pin 14 and the built-in sw/led one.
Just list the codes and what pins, not the whole procedure, if u don't mind