My 2000 F-150 with a 5.4 Liter V8 all of a sudden started "missing". I only have 46,000 miles on it and the check engine light does not come on? It does not miss all the time, but enough to be very annoying. I checked the computer on an analyzer and it showed nothing wrong? The truck was sitting for 2 weeks and when I took it out it started to miss? What should I check out?? Thanks

 

well for one, its a very Low miled unit with only 46k on a 11yr old + truck. congrats
do you short trip this, 2-4miles and shut it off ?? or just don't drive it much?

it may have a injector sticking??....might be some bad gas? Mercon injector cleaner, and seem to be a favorite, & can be found @ wal-mart

or sticty valve?

typically missing is either bad plug or a bad COP...(coil on plug). A low grade missfire from a COP won't neccessarly trip a code right away
I'd check those vacuum lines for leaks too.
cleaning the MAF sensor couldn't hurt.

take it on a good drive....50-150, miles and see if it clears up

 

Yes, I just take it on short trips. Main purpose is to pull my boat. However, I do get it on Xway at least once every 2 weeks for a 10 mile stretch or so. This is the first problem I have had with the engine. Now that I think about it the miss sounds more like an injector issue because it misses a number of times in a row before going back to normal. I will change my gas filter (I put this one on at 35,000 miles) and do some injector cleaning as your suggested and see what happens. I live in the Miami area and things get and stay very hot here, which is not good for gasoline. Thanks again ...............AL

 

short trips are the real killer...everything is not getting up to operating temp before you shut it off, even though you live in a warm climate. In a nut shell, drive it more than just 10 miles, it is getting carboned up...find a town 40-50 miles away and go see whats there

changing the fuel filter is good.

couldn't hurt to clean the MAF sensor and throttle body...changing out the PCV wouldn't be a bad thought either.

trust your using motorcraft oil filters?

Not to say that you may still have a deeper issue like a failing/weak COP. but in the mean time, willing to bet that a couple of healthy drives will improve things, & certainly couldn't hurt.

 

There's a 95% chance it's a COP going bad, causing a intermittent low grade misfire. Which will be hard to track to a particular cylinder. The best thing you can do in that situation is to mimic whatever it takes to cause it to buck and keep it bucking for as long as you can and hope that it trips the CEL. Most of the time you can find that sweet spot right around 40-45mph when it shifts into overdrive with light throttle applied. What I'm saying is, force it to misfire as much as you can... hopefully you will either get the CEL to flash, or come on. Then the DTC can be pulled to determine which cylinder it is.


And, since it sat for 2 weeks, if your using ethanol blend gas, there's a chance it could have separated. Techron fuel treatment is the thing to use.

If you changed the fuel filter at 35k, it should be fine for a few more miles. 15k is a good mark to change them at.

 

thanks Toyz...my bad...I mislabled/qouted that product...yeah Techron is what to use.:o

I gotta a friend that would get this hesistation now and again....like the OP, dove it very little, short trips. Her brother (a mechanic by trade), would just borrow her truck a day or so when it would flare up...(A) trying to get a CEL light to come on & trip a code...& (B) to put some miles on. Never got the code to hit....but by the time he put miles on it , over 50, it was running pretty and smooth again.

yes we have ethonol bleands here in the midwest, & hard not to find it. which maybe contributing to the issue at hand.

 

Thanks for all your input and info. While all this was happening my gas tank was less than 1/4 full. I then filled up the tank with reg gas and changed the fuel filter. I blew out the old one and did not see much in it. But ..................it seems to run fine now! Is it possible the full tank of gas stirred up the crap in the tank? Since I do not drive the truck much is it possible that I get more rust in my tank? Should I pull the tank (this winter) and see how much crap is in it? Is there a filter on the fuel pump in the tank? Thanks ....AL

 

There a sockpre filter that lasts along time generally.. Maybe your just down to some bas old gas. Tack the thing out for a nice long ride. Clear the oold gas out and run some techron through it.. that migh cleaar it up.

 

Well, I thought the problem was fuel related and I "thought" that filling up the tank solved the problem, but NOT SO!!:
Same problem after 3 days or so. It misses much more just after it shifts into 4 gear (auto trans) and I accelerate gradually between 40 -50 MPH. During some trips it does not miss at all? I pulled my boat (4,000 lbs) to the marina yesterday and no miss on the 7 mile trip to the marina. But on the way back it missed quite a lot. I will go through the suggestions that all you gave me (thanks)and see what happens. If I can "induce" the code on the computer this would help a lot (I think)!

 

I would change the spark plugs on general principle, and be prepared to change one or more cops.

 

when was the fuel filter changed?

 

I just put on a new fuel filter last week. The old one was clean. It had been in for 16,000 miles .....AL

 

did the miss start right after the change or before?

 

The miss happened before I changed the filter and after. See my previous posts....AL

 

Sounds like a coil to me.