5.4 missing under load

429scjgt · #1 (**permalink**) 12-12-2007, 10:42 PM

my 2000 F250 w/5sp has a miss under load.It happends after it warms up, if set over night and miss the rest of the day.This just started all of a sudden!!! On level road it runs ok but will miss with the smallest of hills are even taking off from a stop!!! I have changed the plug boots a few times and went thru them last weekend ,found nothing bad there but replaced two of them..Where should i look next ?????

LxMan1 · #2 (**permalink**) 12-13-2007, 04:14 AM

Sounds like you have a coil failing. It will be hard to pinpoint which one without live data logging.

projectSHO89 · #3 (**permalink**) 12-13-2007, 07:37 AM

See if you can induce the failure, then really hammer on it until you get the CEL to come on. The stored fault code should then tell you which cylinder(s) is (are) at fault.

Steve

429scjgt · #4 (**permalink**) 12-13-2007, 08:35 AM

The CEL is that the check engine lighton dash?? So for no light has come on,but i will (stand on it today and see if i can make it come on). Thanks for the help

Toyman · #5 (**permalink**) 12-13-2007, 09:43 AM

Did you recently wash the engine, or go through a really deep water hole. I ask this because I steam cleaned my engine compartment a week or so ago and after mine ran the same way. It took about 5 days before it was back to normal. I cleaned my enigne off to pin point an oil leak, if you were wondering.

Toyman

429scjgt · #6 (**permalink**) 12-13-2007, 05:11 PM

Have not washed are ran thru water.Have tried to get the CEL tocome on today an can't get it to.If it was a coil what would be a good way to check one????

pony · #7 (**permalink**) 12-13-2007, 07:11 PM

I have an 02 F250 with a 5.4 and 6 spd. and it developed a miss under load...more a stumble that was inconsistant. The truck sits a lot so I thought maybe it could be water/condensation build up in the gas tank. I dumped in some gas line antifreeze (to absorb the water) but it didn't seem to help. I then cleaned the throttle body with spray cleaner..it was filthy (58,000 km. Canadian). Ran nicer but still had the stumble. Eventually I used the tank of gas and was ready to take it in to the "shop" if it still persisted after a new tank of gas and some fuel injector cleaner. Since the new gas it's been running "smooth as silk" I think I just picked up a bad tank on my last out of town fishing trip...