I have a 2001 F150 Supercrew w/ a 5.4 just the other day it started missing and had service engince code read which said missfire on #6, replaced coil. Still have missfire, any suggestions.

 

Hi dakotamrd and welcome
How old are your spark plugs?
I would try a new plug before I did anything else.

 

Replaced with Bosch Platinum last summer, replaced C.O.P on number 6 plug and is running great, of course this was after I figured out which was the #6 plug. Have had GM V8's before and found out that numbering is a little different. Thanks for the reply.

 

If the plug doesnt fix the problem, you might want to run a compression check. I have seen many a burnt valves and sometimes a broken valve spring or a rocker arm that has jumped off on these engines. One way to do a quick check is to hold the throttle to the floor (NOTE* THIS MAY NOT WORK ON SOME MODELS) this shuts the injectors down so no fuel flows, and spin the engine over for ten seconds. (NOTE* IF THE ENGINE SHOULD HAPPEN TO FIRE UP, RELEASE THE PEDAL AND KEY IMMEDIATELY) The engine should spin over as if it is just out of fuel. If you notice it sounding like one cylinder is weak or has a miss or like it is out of time such as a broken timing chain. You may have a problem. (PLEASE DONT TRY THIS IF YOU DONT FEEL COMFORTABLE DOING THIS). Pull all the plugs and do a normal compression test instead. You might want to take a stethascope and listen to the injector to see if it sounds like all the others while the engine is running, it should be clicking. If you dont have a stethascope, use a long screwdriver (I have a 24inch phillips head) stick it to the injector and the handle to your ear, it works just as good. Remember though, just because its clicking doesnt mean it's flowing fuel. More than likely it is, but not always.



Oh well, You responded wile I was typing this up. Maybe this info will help you in the future

 

TROLL45, i like the name, you should stop by the super duty forum, i hear they realllly like trolls there...lol it would be good for a laugh or two, once they figured out that your name really is troll45, anyways..... just wanted to say hi and welome.

 

Hey there f=250 thanks for the welcome. If I see something in the superduty forum that I can help on. I'll be glad to stop in and give a holler. I have been called Troll for quite a while now.