Drove my truck to work this morning and it ran fine. Drove home and it has developed a miss. I took all the COPs off and did an OHM test on them and they seem fine. Plugs look good also. With the engine idling it sounds good but under a load it misses. I took each COP off with the engine running and you could tell when I took each one off so Im under assumption that they are all good. It really acts like an ignition problem but Im going to change the fuel filter tommorrow and get some fresh gas. It sure dosent act like its fuel related but anything possible I guess. My Superchips handheld says there are no codes thrown....Im at a loss. Any ideas???

BTW....99 Superduty 5.4L

 

Bump

 

Ok... do a search on cleaning the EGR & throttlebody ... Then check and make sure you have no vacuum leaks, esp around the PCV elbow... If that fails, whens the last time you changed your plugs? You can also do a search for misfires, I typed up exactly how the PCM senses them, and what can cause them... Good luck, and if you have any more questions, post 'em up...

 

Not sure on the plug change....I took them all out and they look good. They are autolite plugs so I think they have been changed before. Stock are motorcraft I assume. 88K on the motor. Ill clean the EGR and throttle body this afternoon and see if it helps. Thanks for the info
buck

 

Cleaned the EGR, throttle body, MAF sensor, and changed the fuel filter but still have my miss. Idles good but misses horrible at any other RPM range. Still no codes. Im sure it is ignition but I have no idea what cylinder

 

filling the plug boots with dielectric grease can make a world of difference sometimes.

there is no really good way to tell if a cop is bad without expensive dynamic test equipment. the ohm test is just an easy way to tell if one is bad if the resistance comes up wrong.

i've always found that the best thing to do is drive the truck hard with the miss happening. if the miss happens x number of times per minute or second or whatever it will set off a code. if you back off the throttle when the miss is happening then the frequency of the problem stays too low to set off a code.

you could buy a new coil and switch it with every coil on the enigine until you find a bad one. seems like alot of work. if you do try this, start with cylinder #3 and then #4. it also seems like #5 goes bad more often too.

 

did your truck get wet i/e anyheavy rain lately
mine does this after every rain i have changed coil packs plugs egr fuel filter plug wires used the dieelectric grease etc etc etc
then i took batttery cable off to reset computer and it ran fine till the next time it rains

 

No rain here....Its been dry. Im at the point that I think im going to buy a new coil and just start swapping them out till I find the bad one. Sure make it easier if it would just throw a code.....Gotta love technology!

 

Problem fixed....Boutght one coil and started replacing them one at a time till I found it. I got lucky, it was the first one I did...#2
Thanks to everyone who helped out with this nitemare
Buck