Ignition Coil Ends for a 4 Cylinder - P0304

[DynoXG]

I have a 94 c220 4 cylinder.
I got a CEL with P0304 - Misfire on cylinder #4.

I did a lot of reading in the forum and the most likely culprit is the ignition coil ends. I already changed the wires. I read that the "ends" are under the coil, between the spark plug and the coil. That's what I don't understand, do the coils have their own spark plugs besides the ones in the engine?

Also, anyone know the coil #'s for a 4 cylinder looking from the front of the car to the back?

34
12

or

24
13 ??

Any help much appreciated.

[dantedawg]

this happened to me last month. ill drive my car in the morning to work..then after about 4 to 6 hours( doesnt really matter)...my car shakes as if the engine's going to die. engine light on as well..try restarting your car, shaking should go away. if not then it's easier to find the problem. in my case i still could not figure out.

so i changed the ignition coils, spark plug connector, and wiring.
but it did not fix the problem coz i still get it once in awhile..
i have a scanner in my car and i get the same p0304 code. i just erase them everytime.

try checking the fuel filter ( clogged maybe? ), and other wiring. plugs too.

pls help guys.

[714guy]

on my inline 6, on the back of the black piece that covers the coils plugs there is a diagram.

Whenever I have a Misfire problem I always try to eliminate the culprit.. usually I'll start with the sparkplugs, then the boots and finally the ignition coil itself. I usually just switch them around to find which part is bad.

Good luck.

[DynoXG]

Thanks 714guy.

I found the answer to one of my questions. The 6 cylinder has a spark plug under the coil:

http://i123.photobucket.com/albums/o288/dynoxg/2.gif

and my 4 cylinder does not:

http://i123.photobucket.com/albums/o288/dynoxg/1-1.gif

But I would still like to know the order of the cylinders. :)

[dantedawg]

Does it mean theres 2 more spark plugs connected to the coils aside from the 4? (4 cylinder)

[DynoXG]

No, only 4.

Some of the V6's have 12 plugs.

[xvvvz]

I think you just need to take the cover off and look ;)

Maybe it is different with older cars but with a 99 4 cylinder it is like the top picture where the coil is on top of one of the two plugs it services. I just double checked the graphic in the Haynes manual and it indicates that the cylinder that is closest to the radiator is #1 and then it goes back in order 1-2-3-4.

[dantedawg]

Originally posted by DynoXG
No, only 4.

Some of the V6's have 12 plugs.

does shaking go away when you restart the car?
my car is still fine ..it hasn't been acting strange lately.
im still gonna have that problem checked. winter weather could add to the problem.

[DynoXG]

Thanks xvvvz.

Dante, no, the problem stays after restarting. I ordered the coil and we'll see what happens. Last night I changed the spark plugs, no difference. The wires I changed last week, so we'll see if it's one of the coils.

[xvvvz]

By the way, have you ever replaced your wiring harness?

[dantedawg]

Originally posted by DynoXG
Thanks xvvvz.

Dante, no, the problem stays after restarting. I ordered the coil and we'll see what happens. Last night I changed the spark plugs, no difference. The wires I changed last week, so we'll see if it's one of the coils. ok let me know. They get expensive too with the sparkplug wires etc. Is the wiring harness same as the spark plug wires? Theres only a couple of things too check to solve that problem. Let us know.

[DynoXG]

lol. no xvvvz. hey, let me keep my hopes up on the coil. :-)

It's a 94! 4cylinder, its been salvaged twice. I could buy another 202 with the money I'll spend changing the harness. ;-)

I'll post after changing the coil.

Dante. the wiring harness is the whole "set" of all the wires under the hood.

[DynoXG]

Hey xvvvz, guess what, you're right after all. :(

The wires going to the coil were completely stripped/bare. I tried to cut them further back but the plastic surrounding the wires just crumbled in my hands when I tried.

I cannot believe the bad quality of the wiring harness. An electrician is going to try to repair only those wires this weekend and try not to damage the rest. But if he is unable to do so I would need to replace the entire wire harness.

Thanks for the input. I'll post what happens.