Hello,
I have a 2001 f150 5.4 with 200,900 miles.
Just bought the truck about six months ago off my dad when he got a new one. I am now experiencing what seems to be a slight missfire. With the hood up pulling the throttle around 2200 rpm starts making a loud knock. Above that rpm nothing and below that nothing. Standing by the tailpipe it sounds like a small backfire. It Idles realy rough and when you get that sound out of the tailpipe it jumps like its hickuping. And tailpipe is vibrating quite a bit. Things i have done in the past month include replacing the pcv valve, changing spark plugs, cleaning throttle body, cleaning MAF, took down exhaust to check cats because i was experiencing a power loss and bogging. When the exhaust was off i punched the two rear cats. I ran a bottle of iso heat in the gas. Everything seems to have helped the power problem but now less than a week later i am starting to experience the knock and backfire type sounds. Any help would be GREATLY appreciated.

 

most common "miss" is caused by bad COP ( coil on plug) ....... if the miss gets bad enough you will get a code light on the dash.. No code yet ? When you changed the plugs you put the original coils back on.. are you sure all are seated good on the plug end ? did you get any excess lube on the rubber that could have caused a short or spark jump ? any water or excess crud noted around any of the plugs ?

 

I had a cop fail on me about a month after i bought the truck and what its doing now is nothing like what it did then. About 2 monthes ago i started the engine and a plug blew out of the head. So i had a helicoil put in and new plug and coil. The only thing that is on the ruber boots is dielectric grease that i always apply when putting in the coil. There wher a few coils that when removed had some slight brown colour on the boots and one with a few droplets of water on it.

 

If you changed all the plugs then you can rule that out as not the issue, purchase a complete set of COP's from amazon if you want and change those out and let us know.

 

That is one thing i would like to do but they are a little pricey. I have 3 new ones in im just going to geep working my way around. I was also thinking about testing the o2 sensors in case they are telling the computer to dump in to mutch fuel. But the biggest thing that is worrying me is the knock at 2200 rpm. I would like to sea foam the engine cuz it has not been done in a while but it scares me to beat the carbon out with that knock. Why would it be only at that specific rpm.

 

It is possible there is knock that is hard to hear and gets louder around 2200rpm instead of just happening at 2200 rpm. You can also get a set of 8 COP's on amazon for around $50.

 

The coils for $50 are not motorcraft. I have heard to many bad experiences with people using other than oe coils. The knock from what i can tell with my head right at the engine is not there untill you hit that (not so sweet) sweet spot.

 

Correct not OE coils and I've been running them for a while without any issues. Let us know what you find out.

 

I may give it a try if all else fails. Im thinking about taking it to have full diagnostics run but that can be verry expensive. How long have you been running the coils with no issue?

 

I had horrible hesitation and missfire issues with my 98 expedition. I ordered a COP set on amazon and new motorcraft spark plugs. A couple of the spark plugs wouldn't come out so they had to drill a couple out with an extractor. With the new COP set and spark plugs installed for the past 2 years it runs a lot better. I even tried seafoam when I was having the missfire issues and nothing fixed the issues I was having until I put new plugs and COP's in.

 

I have tried as mutch as possible to avoid non OE coils. But for that price i may give it a try. Even if they do fail later on i will atleast know if its any of my problem.

 

I have bought 3 sets of "non OEM" coils off e-bay over the past 10 years. I have only replace one original full set. The new noo-OEM I use as "spares" and replace one as an OEM fails. I loose about 1 coil per year. Couple of the non- OEMs have failed in 1 year. Some are 6-7 years old. I don't believe they are the same quality as OEM and have a higher failure rate, but it only takes 10 minutes to change one out... after you get the correct code / chlinder.

 

I have replaced a few alread but i guess im just gunna go ahead and order a cheap full set and see what happens. Though i have a feeling its not going to correct the problem i am having. I have checked preety much everything outside of the engine. I am starting to fear that it is internal. But its really ticking me off that it refuses to throw me a code to work with

 

Do you happen to remember witch brand you got?

 

I was also thinkin due to the symptoms and things i have read that it could pissibly be in the EGR system. Does anyone have any experience or input with that problem?