78,000 3yrs old 4.6 2002 4 door
a shop. Should it have been tested, since the engine light has never come on to tell the sensors? Originally i bought a fuel filter, and 2 shops told me a test should be run before they start guessing and installing it.

When you stomp on it, it's ok. When it lugs, it starts to miss. when it hits overdrive at 55mph, that's when it starts to really miss (at that low RPM).

thx for the response.

 

DMch,

I can't find my Chilton's Repair Manual, but if anybody's got one of these books please check the back of the book for a descriptive reason for plugs being a different color. There are a few different examples of photographed plugs and how to read what the problem may be. Then reply to DMch to answer his question, and to share with other guys as well. And DMch...don't use the Autolites...go back to Motorcraft; the way Mr. Ford intended it.
Phil

 

CDavis

My truck did the same thing started to miss at low rpm's. I really noticed when it missed when I was going uphill on the highway doing 65. The miss set a code for a missfire.

 

DMch,

I found my Chilton's Repair and Tune-Up Guide. Concerning the black spark plug you encountered, it says it may be due to Oil Deposits. It further says,concerning the "appearance", the firing end of the plug is covered with a wet, oily coating. The problem is poor oil control. On high mileage engines the oil is leaking past the rings, or valve guides. Another common cause is a plugged PVC valve, or a ruptured fuel pump diaphragm. If you think it's Carbon Deposits, and only one or two plugs are carbon fouled, check for carroded or cracked wires on that plug (s), and look for cracks on the distributor cap between the towers of the affected cylinders.
Well there you go, and good luck.

Phil

 

Thanks PHILCOPGM
The truck has 295000km on it and I haven't changed the PCV yet. It is most likley an oil leak.
Dave

 

To begin with I would like to thank Racerguy for a great original post. This is probably as useful as any single post in this entire forum.

I have a concern about something that evolved as the thread progressed that could lead to SERIOUS INJURY! For this reason I can't stand by, with a clear conscience, and keep my mouth shut without pointing it out.

Racerguys original description of the process is TOTALLY safe. Where I was alarmed was reading two different things that were done by different posters that if done in combination could be HAZARDOUS!

Several posters mentioned using a shop vacuum to remove debris from around the plugs before removing them. By itself this is probably no safety hazard.

ANOTHER poster mentioned how easy it was for them to pull the fuel rail.

Now, if you were to do BOTH these things, you are looking at a potential SERIOUS FIRE HAZARD.

NEVER, NEVER draw gasoline into an electric vacuum cleaner. People have been KILLED doing this.

I personally will never use a shop vac under the hood. Maybe I am overkilling the safety issue with that statement because USUALLY there are not flammable fluids under the hood.

When the fuel rail is apart, however, there is gasoline exposed and it would be VERY dangerous to use a shop vac under the hood at that time.

PLEASE BE SAFE!!!!!!!!


Doc
Certified ASE Master

 

Good point Doc

 

Another side note to doing the plugs (& installing a K&N FIPK!), I had a problem when
removing the P/S bracket. It seems the stud on my t-stat housing loosened as I
removed the bracket, causing a slight leak in the #5 plug well (coolant). I was made
aware of this with a mis-fire on the #5 cylinder several months later. There was
probably 3-4 inches of coolant in there when I pulled the boot. You can only imagine
my relief when I found the t-stat housing bolt loose, and I didn't have to attempt the
dreaded intake manifold gasket (or worse, replacing the whole intake!)

 

Thanks Racerguy for the original post. I just bought my truck three weeks ago. 2002 model 5.4 V8 with 130000 miles. Every weekend I've been changing fluids and filters. This weekend, with the help of Racerguy's great info, I decided to tackle the sparkplugs. I've changed plugs and wires only twice before. Once on an old 4-cylinder Chevy Cavalier and again a few months ago on my V6 Ranger. I thought the two hours I spent on the Ranger was a PITA. These V8 F-150's take the cake. The first time I looked at it I thought it was going to absolutely impossible, but after four hours and a few rough spots on the hands (no broken knuckles though!) I got it done.

I definitely recommend the low-profile swivel 7mm socket for the #7 COP. I don't have one, but it would have been so much easier if I did. The fuel pressure thing-a-ma-bob is directly on top of the #7 COP screw and using a regular 7mm socket with a 1/4" u-joint makes for very tight fit. I loosened the fuel rail a bit without taking the bolts all the way out, but it really didn't help much.

I also recommend discarding the rubber thingy in your sparkplug socket. I had just finished with #4 (the hardest one of all, IMO) and was moving on to #3 (I went in reverse order, from #8 to #1) when I noticed the rubber thingy was gone. I knew it was there when I started. The last thing I wanted to do was disassemble #4 again, but I saw no alternative, so that's what I did. I pulled the COP and firmly attached to the end was that d*mned rubbery thing! Promptly chucked it into the nether lands, cussed a bit, then tried to reassemble #4. Since I couldn't see the hole I just had to feel my way through it and kept jamming it into the dirt on top of the cylinder head. Pull it out, clean it off, find the hole (blah, blah, keep the dirty jokes to yourself ), try it again. The rest went like clockwork.

Four hours total, not including a couple of smoke breaks to cool off and quit cussing. Took the truck out for a drive and it ran great. I noticed it's idling slightly slower now, at stop signs and redlights. Idling in Drive around 700 rpms, smooth as butter. I hear you're supposed to retorque the plugs after 500 miles. Uggh!!!

 

Good to hear another success story

The 7mm swivel socket really does make a big difference.

I've never seen anyone retorque their plugs. If they are torqued right to start with it shouldn't be necessary.

 

I got the same message from the local Firestone technician. According to him, Ford issued a service bulletin (late in 2005) regarding the mandatory re-torqueing. Apparently the new plugs can somehow work themselves loose in the first 500 miles and can be thrown if not re-torqued. Doesn't make much sense to me, but probably a smart preventative measure.....

 

i recently changed the plugs in a 1997 (4.6) and boy i goofed it up real good by installing bosch plugs.the gap's were correct and it ran like a 2cycle outboard motor!i took the bosch plugs out and replaced them with the motorcaft and it ran perfectly.i highly recomend that you stick with motorcraft plugs for this paticular engine.it's not like the old day's choose a plug brand and stick it in.unless you wanta go fishing...

 

I'm getting ready to give this a go myself. I called the local Ford dealer to price parts ($8.27 per plug? $60 for serpentine belt? $150 for set of spark plug wires? Ye cats, that's twice what it costs elsewhere!) and asked whether there had been any recent bulletins advising re-torqueing the spark plugs after a few hundred miles, he hadn't heard anything about that. Just called another Ford dealer and asked the same question, got the same response.

 

I have a 2001 4.6l f150 and i have the same problem as you stated.. I have taken my f150 to the dealership 3 times and they can't seem to reproduce the misfire or whatever seems to happen betweeen 40-50 mph. I only happens under a load and moderate to mild acceleration. It also only occurs when shifting into the overdrive gear. If you acclerate hard it goes away when you pass 1500 rpm. I tried to take it in to the dealer and on the way a plug and coil went out. The error code came up and they thought they fixed the problem but it still is not right -but it is a little better. It is really frustrating i wonder if changing all of the plugs might help? coils too? I only have 75000 miles on this engine and it really makes me mad that the ford dealer can't figure it out. This has been going on for 1.5 years!

 

bdski has your transmission fluid ever been changed? A shuddering torque converter clutch can feel like a misfire.