2003 F-150 SCrew 5.4 120,000 miles. Bought used 2 years ago and have had NO problems with it...Yesterday I changed the oil & filter, air filter, and then cleaned the engine - degreaser and rinsed. Today I drove it 30 miles, then it started missing very slightly, then progressively got worse. Tore the engine compartment apart looking for loose wires, disconnected hoses, or wet connections, but found nothing. Started it back up, and runs worse than ever, even at idle. No SEL showing. I am 20 miles from nearest trustworthy mechanic, so will probably have it towed there Monday, since I don't want to chance destoying the engine (don't have a code reader). In the menatime, anyone with any ideas? I realize it can be any number of things from plugs to coil to egr to MAF, etc., but I wonder if it had to do with rinsing engine off...Any experiences with that? Thanks...(Sorry for the long post)

 

yes im more than sure putting water directly on your engine is a bad idea. I would check for water in the area that the plugs are in. i would get an air compressor and blow out those holes really good, as well as the inside of the wires/cops to make sure water isint causing any arching. Water conducts electricity so i would bow out any connectors that really got a hosing no pun intended. Next time I would "hand clean" if at all possible.

 

This is why I NEVER wash my engine down with water, hope you get it figured out without taking it to the mech...Is it on the road somewhere?

 

i had the same problem on my 98 5.4 after i washed my engine. turns out i messed up the number 8 COP ya know the one that it would be easier to cut a hole in the dash to get to. i would get it to your mech im sure thats what it is. hope you get her fixed and back on the road soon!!

 

Thanks for the replies. Yes, it is in my driveway, and tomorrow I will take a compressor to the entire engine and see what that does, along with giving it another look-over. That before I give up and take it to a mechanic. I guess with all of today's electronics we can't treat these engines like we did in the "old days".

 

You have most likely shorted out one or more coils.

 

So, today I pulled every coil and blew out the spark plugs, found one that had the slightest bit of moisture in it, disconnected the battery for over an hour, and buttoned it back up (everything looked good). Would have replaced the spark plugs had I had some foresight - stupid me! Truck idles in park and neutral with no problems (which is better than before), even when revved to 4K. As soon as I put it in gear, I can feel it stumble slightly. On a drive test it stumbles badly between 40 and 50 mph...I am not a transmission guy, is it possible I have a transmission problem at the same time? Still no Check Engine Light...

 

yup, get 'em changed

 

Cop's are shot

 

When were plugs changed? When was fuel filter changed? But, most likely, you have messed up a COP with the moisture.

 

Plugs and fuel filter changed 23k ago. New plan is to take it in for diagnostic check, then replace spark plugs and (bad?) coil if that's what shows up - myself. I have two questions: (1) Will a diagnostic check show me exactly what COP(s) are bad? (2) Do you guys suggest OEM for the COP - Motorcraft? And who has the best prices? Thanks again for all the help - it's been a while since I've gotten my hands dirty in the engine compartment...

 

Disregard that last post, after reading several other threads I will certainly go with Motorcraft, and will check with reputable dealer for the best price...looks to be around $50 each for the COP. Does anyone know of a low cost scanner that would help in my situation rather than taking it to a shop?

 

autozone can read codes and tell you what cylinder is misfiring.

 

If only I didn't have to drive 50 miles to find one, and thinking I don't want to put the truck thru that abuse before I know what's wrong with it...

 

You can buy a whole set of 8 cops on Ebay for about 80 bucks with a lifetime warranty that are just as good as OEM. Search for "DG508" and get them from Global or Uneek.