Misfire diagnosis

[Bojans]

First off let me apologize for this being off topic, but an intermittent misfire is turning into a more constant problem that I would really like to just get solved before trying to take my wife to the hospital for baby #2 in the 16+" of snow they are forecasting...

2006 Explorer 4.6 V8, ~ 90k miles

Code P306 - cylinder 6 misfire. Swapped coils with the # 1 cylinder and still have a P306. Next step to replace the injector on number 6? Spark plugs were replaced ~ 20k miles ago...

Thanks for the help.

 

[Ohio Auto]

Change the spark plug first. Could easily have a cracked insulator. Also..wouldn't hurt to run a quick compression test on that cylinder while you have the plug out.

 

[Lotek]

Check the plug insulator for carbon tracks, if they are there, change the boot as well.

 

[regguy1]

I've had several of those with bad plug wires..lokk at night you migh see arcing.

 

[Richball]

I hate to add this , but do a compression check on 6. Had the same problem on our '02 Escape on number 2. Replaced plugs, swapped out coils... It turned out to be a bad piston. Ended up putting in a remanufactured the engine I could get a deal on.

Good luck. I hope it just a plug or injector.

 

[Milton Shaw]

That code is sometimes set from the EGR system ports stopped up and letting all the exhaust go to the number 6 cylinder instead of being spread through all the cylinders. Clear the code and see what happens, there is normally not enough of a misfire to actually feel a misfire but the computer will catch it.
To fix this requires removing the intake manifold and cleaning ports in it and in the heads. Big job just to clear a code that doesn't really cause a problem. This only applies if you can not hear of feel a misfire actually occurring.