The misfiring cylinder 4 on my '99 CL2.3 is a baffling problem. I replaced rotor, ignition coil, distributer cap, spark plug wires, and the spark plugs and only cylinder 4 misfires, really no change in performance at all. The car has 174k miles, so she's getting a little long in the tooth. When I pulled the plugs to replace them plugs 1 - 3 looked good, I had just replace all 4 last summer. Plug 4 was fouled with a black, grimy deposit, which I assume is oil. Once I found that the #4 plug was fouled I figured putting the new plug in would make things much better...they did not. Interestingly, when I pull the spark plug wire from cylinder 4 the engine performance doesn't change at all (pulling the wires from the other cylinders almost cause the engine to shut down). It sounds like a compression test is in my near future. Any other ideas, suggestions, or potentially useful comments?

You help is much appreciated!!!

John

 

your only real choice is a compression test but make sure to keep an eye on battery level or the whole thing will be wrong and a waste of time (i use a battery charger while cranking)

 

Im having the same damn problem, except now P1399 came up as well! have u gotten ur Cylinder 4 Misfire fixed yet? Hope someone answers this question cuz i can't seem to get rid of the Cylinder 4 misfire!

 

the 1399 code is pretty mysterious from what ive read on HT and other sites, it seems like a catch all for a misc missfire i think the name is "multiple cylinder misfire".

my friend has a 98 accord and got the 1399 along with other missfire codes. he gapped and replaced the plugs, wires, distributor cap and rotor, and coil with no change. we also seafoamed the shit outa his car and cleaned the IACV and EGR valve and port with no luck. timing and compression came up good aswell. the ECU tested good aswell. it all started after he filled up at BP, but after draining and refilling the gas tank nothing, injectors are all cycling normally. fuel filter on those was in the tank, its a stupid mesh screen they call a fuel filter and thats clean. fuel pump is good.

there seems to be some possibility that a burnt valve could cause this misfire code, thats what hes going to have checked next.

 

I realize this is an old string. We're keeping this vehicle alive as my 17yo son now drives it. May I ask of anyone ever figured out this random misfire? Especially cylinder 4, but others too.