My 99 F150 5.4L 4x4 developed a horriable skip on the way home today. I was driving and it started as a studder, now it is a full out truck shaking skip under a load and a noticable skip when not under load. I have pulled the coils, and plugs, all look good. Put dielectric grease in the coil boot and reassemble them all, now the skip is even worse. I hooked a code scanner to it even though it had no check engine light on and it had no codes even though its skipping bad. Any ideas??????????

 

Did you test the coils? Pulling them and looking at them wont help a thing.....Also did you test the injectors?

 

When was your fuel filter last changed, plugs as well?
A Haynes book, (about $10) & a digital multi-meter to test ohms & volts are 2 great tools to have.

I know I cannot be without either. In addition you can purchase Hayne's Code book for more details in regards to codes instead of the basics regular Hayne's book offers.

 

The plugs were changed about 5000 miles ago with no problems until now. The fuel filter was changed as well at that time. I did not check the coils or the injectors as i dont know how. Im getting a book today and hopefully it will tell me how to check them. Im almost positive that it is coil but I just dont know which one yet.

 

A quick tip that I do and it works for cop's as well as injectors is with the engine running unlpug each one and listen for a change in the way the engine runs.....if you dont hear a change then you found your dead coil.

 

I tried the unplugging method but my hearing is so bad from being blown up 9 times in iraq i couldnt tell a diff. Im gonna try to check the resistence in the coils tomorrow to see if i can find a bad one. I noticed that the boots seemed to be coated in that elec grease and I was wondering if that crap got inbetween the end of the coil and the end of the spark plug would it cause a short?

 

No that grease supposed to be there and I doubt its enuff to hurt anything...If its throwing codes autozone can tell you which one it is.....and if it aint throwing codes you may get someone else to check it for you.