I have a 2001 F-150 5.4L 60,000 miles. Three days ago I changed all the plugs(Motorcraft Platnium) & fuel filter. Today while I was driving it started missfireing/studdering bad. Mostly under a load or when I accelerate. I got home, pulled all 8 coils off & re-seated them, test drove it & it ran perfect! About 3 hrs later went somewhere & it came back, after about 30 min. of driving...this time the service engine soon light was blinking & it run terrible, except when I stomp it. I pulled the PCV Valve out & it was making a loud chattering sound...when I put my finger over the hole it did suck though..is this chattering sound normal? Also, which type of scanner do I need?

Please help!!!!!

 

You need an OBD-II scanner. Check to see if any local auto parts stores will scan your codes for free. Several chains including AutoZone and Advance Auto Parts do this.

Write down the exact code(s).

Come back here and use the SEARCH tool by entering the "PXXX" code into the search keyword field.

My guess is that you will have a code between P)301 and P0308. Most likely cause will be a flaky coil that fails as it gets warm.

The PCV valve should rattle when you shake it to make certain it is not gummed up. If in doubt, replace it with a Motorcraft (not an aftermarket) replacement part.

Steve

 

Just thought I would post a note here in regard to my 5.4 with 80k. Several weeks ago when engine was started for the first time in the morning it wouldn't idle. It has done this a couple of times but then problem when away. I got caught up in here and it looks like problem is the IAC.
Well, over the last few weeks the engine developed a minor miss when accelerating between 1500-2500 rpm. I figured the IAC probably needed to be replaced. A few days ago the truck started running very rough and I wasn't sure I could get it home. It ran ok at a steady rate of low rpms but it would not accelerate. I replaced the IAC and it didn't run any better. So I went ahead and replaced the fuel filter. Don't have a gauge yet to check pressure, but it felt like it was starving for fuel.
I decided to replace the Bosch plugs that had about 20k on them after reading about some of the guys having trouble with them. I couldn't find the double platinum Motorcraft plugs locally so I installed Autolite PP103 plugs. Well, unbelievable, but this solved the problem. The Bosch plugs did have an excessive gap. The truck runs very smoothly now! BTW, I had the rep at Autozone check codes when it didn't run well, and nothing came up on his meter except "Pass". Thanks,

 

I replaced my spark plugs a while ago, and shortly after, had a misfire like you are talking about. As it turns out, it was a bad coil boot that wasn't seating properly and it had to be replaced. An OBD-2 reader should tell you though. The codes for misfire to figure out which cylinder it is are:
P0301 : Cylinder 1 misfire
P0302 : Cylinder 2 misfire
P0303 : Cylinder 3 misfire
And so on. Mine was a P0307, the 7 cylinder boot was bad.

 

I am having the same problems with my 2002 f-150 4.6L. I replaced the spark plugs with motorcraft plugs started it up for a test drive. It ran fine for a little while then started to miss between 40-50 mph and while stopped. service engine soon light was also blinking on and off. I was told by a mechanic the most common problem for the symtoms is cracked spark plug coil boots. so I went back to the dealer and purchased 8 boots for a grand total of $60 and some change. Got home and replaced them and it still runs the same (problem not solved. I have also changed the fuel filter and that did not help. so for now she sits collecting dust.

 

You are right on!!!!! I went to Auto Zone & got me an Actron OBDII scanner. Downloaded it & it was #8 cylinder misfire(too bad it couldn't have been #1) Well, for now I think that it just needed to be re-seated, but it might be a Flaky coil...it does happen once it warms up!(Thermal Expansion) I bought me a new coil just in case! I AM FIXING TO GO DRIVE IT & WARM IT UP & SEE FOR SURE! Thanks for all yalls' help & past experiences!!!!Sure helped out alot!!!!!

Derek Allen

 

problem found! It was a bad spark plug #7 cyl. I pulled each individual plug wire off one at a time while the truck was idling to see if there was any change in the rough idle. all cylinders ran rougher with the exception of # 7 cyl. there was no change. I turned the truck off and pulled # 7 coil and found moisture on the boot. After looking down the hole with a flashlight I noticed some standing water around the spark plug base, so i pulled the plug and bingo the plug was fouled, so out comes my wifes hair dryer to get rid of the moisture in the plug hole. made a trip to the local parts house for a new plug and she runs like a champ. :