I was driving my 2002 F-150 w/4.6L when it started idling rough and lost power, not completely, but it started lagging big time. It sputters like an old Pinto but it still idles at a consistant 700 RPM, but it's really rough. The only thing I can think of is that I got something wet when I sprayed degreaser on the engine and rinsed it off earlier that morning. It has had plenty of time to dry off if something did get wet so I really don't get it. And the "Check Engine" light HAS NOT come on so I have no clue.
Could it be a clogged cat?
Did I lose a cylinder? Please say no!
Could it be a coil problem?
What could be causing it?
I changed the fuel filter about a month ago so I know that's not it. I changed the plugs about 3 months earlier with no problems since then so I doubt that's it. HELP

 

I have heard that these trucks are notorius for having probs after washing the motor. The first I would do is the plugs. The COPs for each plug can get "shorted" and start giving you probs when you get them wet. I think the number 3 and 4 are the problem ones. I am sure someone else will chime in here before long.

 

I changed the plugs about three months ago and then pulled them out today to check their condition and they were all tight and in great condition. I'm waiting for the truck to throw me a code but nothing yet so I'm trying to do a process of elimination until I get a code. Tomorrow, I'm going to a muffler shop to see if the cats are clogged. If anyone else has any other suggestions please let me know. I'm in serious need of help.

 

if cats clogged you get a code, 5.4 and 4.6s when you washed engine water got into the spark plug wells and shorted a coil unplug one injector at a time until you find one that the engine does not change its rythem. that is your problem cylinder. Replace the coil and plug and be sure to use motocraft platnums. ford mod engines don't like aftermarket plugs. And did you hear a hissing noise from behind engine? The pcv fitting on back of intake is bad to crack just follow your pcv line behind the throttle body until it comes to a elbow and plugs in.

 

I actually got a code last night but when I went to retrieve the code with the Hypertech programmer, it dissapeared. I have no clue why but the programmer didn't even detect it.
I should do your test while the engine is running, correct?

 

The more I drive it the worse it runs. I can't get the idea out of my head that it's clogged cats and they are getting more clogged the more I drive it. After checking the plugs it ran worse too. What did I do to this poor beast for it to treat me like this?

 

A plugged catalytic converter ususally wont cause a rough idle. It will usually just cause a lack of power but the engine wont run really rough.
Like has been mentioned a couple times I think you've got a spark problem, either a bad plug or COP or just water in a spark plug well.
If the check engine light came on there should be a trouble code stored in memory. Does the Hypertech have the capability of retrieving memory codes?

 

It idles rougher than normal but it's still relatively fine. The problem comes when you accelerate...then you have a real lack of power and sputter that you can hear and feel. The Hypertech is supposed to be able to check for codes but it apparently couldn't find one. It was weird, the "Service Engine Soon" light came on and when I got home to check it and restarted the engine the light was off. This thing is a pig right now and couldn't get out of its own way. At speeds of about 35-50 it runs like crap in lower gears but as soon as it shifts up the thing runs so rough like as if all four tires were severely out of balance.

 

Pull out the coils and blow out the plug holes, also clean and blow off the coil boots. Should fix the problem.

 

I think you have a COP problem. It is usually #4 but since you washed your engine it aint no telling which cylinder it is. Try what i said in previous post

 

If you do get a code out of it post it on here. A p0300-p0310 is miss fire codes.

 

I finally got a code....P0357 = "Ignition Coil G Primary/Secondary Circuit Failure.

Does anyone know what this means? COP? And if so, which COP? Does the letter "G" correspond to a number in the firing order?

 

umm i'll have to look it up monday at work that code sounds familar but i don't remember

 

The 7 in P0357 means #7 cylinder as does the G.

 

I replaced the COP on #7 and it runs like a champ....well, at least as good as it did before the problem.

Now I just need to find out why the thing drinks in a one big gulp of air on acceleration and hesitates before it finally hooks up and goes. I just installed an intake and programmer. It doesn't hesitate without the programmer but doesn't have the gains of the programmer either, but it hesitates with the programmer. What gives here? It's a Hypertech, could that be the problem? I want the Diablo...would that be better for a 2002 F-150 w/ a 4.6L?