Number 4 of 6 Missfiring

[Bigredwing]

Hi All,
Newbie to this forum as I just found it researching a problem I have on my 125K mile, 2002 V6 Eddie Bauer Ed. I tried the Search function but didn't locate my problem so maybe somebody out there can give me a hand. What we have is a "Service Engine Soon" light. I had my son take the car for an Autozone code scan and he returned with a print out showing a problem with plug four, plug wire four, or coil 4 being possibly bad. No code number to cross over in my trusty Haynes manual. So today I pulled the plug and it looks good. Gap is also good. Plug wire reads 6.5K Ohms. Plug 5 and cable are identical. I cleaned up all the connections and attached my inductive timing light which did confirm a miss on #4. Since everything else is firing good I am leaning towards a bad coil for #4. Any other ideas or recommendations? Thanks!
-Chris

 

[btexpress]

Makes a big difference to me to know the code. But if you know it is #4, that narrows it down some. Check the plug wire real carefully at the spark plug boot, it may look good but if you see any white spots or a sign of spark leaking then replace the wire. I have found many spark plugs that look ok physically, but for one reason or another they don't fire. Internal short of broken resistor, something like that. It could be a coil, but most times if these coils fail it effects two cylinders.

 

[Bigredwing]

Thanks Dennis,
I was considering the wires even though the resistance is OK. With the mileage I've got it would not hurt to replace the harness anyway. Wires might be cheaper than the coils anyway. Something to check. Thanks again,
Chris

PS- I should have added that I swapped the #4 and #5 plugs and #4 is still intermittent.

 

[Bigredwing]

Update and Fix

I replaced the Coil Pack and the miss is gone. Cleared the Engine Service Soon light and so far so good. I used my timing light to untechnically watch the firing cycles and #4 didn't miss a beat. $66 spent at Advance Auto.