1997 E320 M104 misfire code P304
 

Hi guys!

Developed a misfire, sanned codes came up with:

P304, cyl # 4 misfire
P300, random misfire
P304, cyl # 4 misfire

I changed the spark plugs and spark plug connectors.

Cleared the codes and the MIL atcivated again.

Code read:
P304, cyl 4 misfire.

My question is: I've had bad coils before and I have yet to see a coil FAIL and it affect only ONE cylinder. Could I possibly still have a bad coil????

Any ideas would be greatly appreciated as I am kinda lost on this one!

Thanks in advance, guys!

I've had 2 bad coils in the past so it is possible.

Which plugs did you use? I don't suspect a coil since it powers 2 cylinders which would likely generate a second misfire code. I would very carefully re-check the plug and the connector or wire on the misfiring cylinder.

The last coil I changed , only affected one cylinder...

Jeff, I suppose that it is possible for the coil to negativ ely affect only one cylinder, but how can that be????

If the coil is simultaneously firing both cylinders, then I must assume that it is the same circuit (within the coil), no???

M104 engines have 3 coil wires and 3 high tension leads which piggy back to the next cylinder.

Maybe what is bad is one of these high tension lead wires.

Former NJ resident...what exit..?

BDB,
When the fault code came up, it was for one cylinder...I thought the same as you...how or why..maybe there is one primary and 2 secondaries..?

I should cut one open..(or wait for an expert)

Another former NJ resident...Morris county

Jeff!!!......Somerset County, NEW JERSEY and I miss the place, somewhat!

On a 1997 E320, M104 the # 4 cylinder has a coil pack on top of it and is firing the cylinder through a spark plug connector (i'm assuming that cylinder v# 1 is the one in the front of the engine).........I have no problem with purchasing a coil, I want to UNDERSTAND how this coil can break down in such a way........It's almost unbelievable that this type of coil can be defective on only one cylinder

To quote Arthur Dalton " Move the coil to another cylinder & see if the code ( misfire ) moves with it". ;)