i am randy..i am new to this forum.. ok i have a missfire since 37,000 miles on my 2002 4.6 f150..the 1st mech.and the other mechanics all told me various coils had to be replaced..after buying one i am not convinced..so i changed the plugs.switched coils and swtched them in different cylinders..checked the timing..changed the fuel filter..cleaned he in take bla bla..it seems as if some of the plugs are geting a little corossion around the thread of the spark plug..what in the world: anyways i change the plugs..the computer shows no missfire..cool so a week goes by i give it the gas and boom missfire is back: ok what gives now it reads the 1 and 6 coil is bad with the egr valve..i dont buy it..i change the plugs again..the same thing it is fine for a while and it starts again..has anybody had this problem..help! i am starting to not like ford and that is scary....

 

ok i found some interesting threads..seems as if there is a lot of missfirring issues that was supposed to be the coils but really was not..damn!! that is a waste of a lot of money..but from what i gather from reading these threads the next thing i need to do is check the pcv valve pdf and egr stuff and use plumbers caulk around the boots of my ignition coils to keep em dry..lol.i sure hope this helps..

 

Same thing but not as severe. For 6 months it would run strong one minute then rough and sometimes die at idle then start right back up. There were no codes, the cops tested ok, plugs were new Motocraft. The mechanic blamed the cam, the dyno showed it was running real lean (13.9:1), put in a new high performance fuel pump and adjustable pressure regulator. That made it run even stronger one minute then rough and die!!## Last week it finally threw a code. Missfire #1 plug but it tested fine!!## That did it. Mechanic pulled out the PCM and cracked it open and there it was!! The freakin' pin on the circuit board for #1 was arcing and melted and there was black soot the size of my little fingernail on both sides of the case. It had been doin' that for months. Put in a new PCM and it runs perfect. Moral of this nightmare is open up that PCM and check it real close. The money you save could be your own! Good Luck

 

oh yea the guy at autozone told me to buy a new after market gas cap because the ford gas caps were not that good... that sounds to easy

 

Well in dear ol' Calif a leaky gas cap will cause your car to fail a smog test. The PCM does a vacuum test of the gas tank and if it fails (bad cap, cracked filler pipe, etc) then it stores a code but does not turn on the CEL (check engine light) so you don't even know you are gonna fail the test till it's too late unless you have this great little gizzmo called a Scangauge. Tells you absolutely everything about your engine. Check it out on the web. Also, buy the Ford gas cap, it's only $20 and better than aftermarket.

 

Depending on what truck or car, there are two diffferent test sensitivities employed.
In one, the vehicle is equipped with a seperate check fuel cap lamp and will extingish as soon at he cap is secured and the PCM does it's next vacuum draw down test that passes.
In the second, the system uses the CEL lamp and a code set; after the cap is secured and the vacuum test is passing, the fault code stored should auto clear.
Each of these tests has 4 test phases that do the same thing. Only difference is one is more sensitive (enhanced) than the other.
They use a calibrated orfices of .020" and .040" as a standard to measure the vacuum pulled vs a time period, to determine if the tank is sealed up and reads the sensor at the tank for results.
Anything that interferes with this test will set different codes to tell what to look at first.

 

ok i will try a gas cap.. i checked the egr valve with my fingers after the truck had been running...it seemed to be room tempature...is this thing suppose to be hot? it seems like if air was flowing through it that it would be hot, so i figured that i would ask. because i believe that reading all the other threads that the egr valve might be the problem pcv valve seems to be fine. i do not see any signs of leaks from the heater hose but it still has pinch claps instead of screw claps which i will change as well. if none of this works then screw it i'm buying a TOYOTA.

 

Randy, if things don't work out with your truck, i'll "take" it if you don't want it, lol. We had a somewhat similar problem with a 99, but that's another story. Toyota's are good trucks and pretty dependable, like most import vehicles. I may own a toyota in my lifetime, but i don't think i could give up my f150, even if it has some problems, but since yours is probably your daily driver, i can see the need for a new truck, unless you can fix it. Good luck, and keep us posted.

 

Depending on how you look at it, going to a Toyota can still end up with the same kinds of long term issues because they are PCM controlled in the same general way.
The big problem today is the electrinic control systems are to complex for the average owner to handle unless he has education in how they work. Even the dealer shops are still behind in handling everything that comes up.
This is the struggle you see in nearly every thread dealing with a problem.
Look at the thread about getting engine codes after having exhaust work done; for an example.
There will always be a percentage of owners who will get into trouble making changes, trying to solve faults, and all sort of difficulties.
How it is handled, becomes the difference, in the end.

 

thanks for all these responses this is a really cool site..it is more helpfull than all the other f-150 sites i have seen so far..i just got through trying to work on the truck only to find out i need more tools..i am definitely not an auto mechanic.. i am a commercial plumber so i am still very mech. inclined..i did notice a hose seemed to be kind of dry rotted slightly..this hose said gas/fuel on it and it ran from a pipe around the intake area to this plastic thing with a bunch of other hoses hooked to it located at the very top near the hood on the far drivers side..i think this is the pfde sensor every one is talkin about..any ways i hope i have time to work on it this weekend..i am really going to dismantle the whole thing and pray for the best..any advice will be appreciated..i will definitely keep yall posted as this might help somebody else one day..thanks

 

That is the vapor management valve. I don't see where you have told of any codes. Has the check engine light been on? If so, what are the codes? Also, do you regularly wash off your engine compartment? If you do, water will get into the plug holes and cause misfires. Just a thought. The dpfe should be a little black sensor with two hoses connected at the bottom coming from the egr tube. I'd like some more detail of your problem to better help you. And by the way, don't use plumbers caulk, use dielectric grease on the bottom of the boots. I hope you were kidding. Yes, the egr would be hot at idle if it was operating improperly. It should be cool to the touch. The problem with the pcv valve is the elbow that attaches behind the throttlebody causing a vacuum leak, not the valve itself.

Robbie

 

well if it will help a little info i did not mention..i did have a flashing check engine at one time with the old plugs and the new as well, until i cleaned all the plugs and wells for the plugs and put seal grease around the boots of the coils..but like i said the check engine light is still on and it is running like a real bad missfire again..and let me mention that the cheap pocket computer at autozone shows a bad egr valve as well..but i will not rely on the cheap pocket computer at autozone..

 

oh yea bigbronc..and the light is on but not flashing no more..yes,i always joke about plumbers caulk and duct tape..i did use dielectric grease around the coil boots..as far as codes idunno..but what the mechanic said it showed was the 1 and 6 coil needed to be replaced..i do not see how it could be the coils..

 

Rockinrandy,
Just my .02: are your plug boots backing off the plugs? I had that issue but a recrimp fixed the problem. Intermittent rough idle, stumbling on acceleration; thought I had water in the fuel. In fact, when I popped the hood, I could hear the spark arcing to the plug; boot had backed-off twice before I fixed the crimp. No problems now for 2 or 3 months.

 

what do you use to crimp the coils and how..thanks