I have a 2004 Ford F-150 5.4l V8. It has been giving me issues for that past month or so. The truck idles really rough when under 1000rpms. The truck drives really sluggish coming off stop lights. When I am driving it in between 40mph and 60 mph, the truck misfires if it is under load(going up a hill and pressing the gas slightly). The truck shakes pretty violently when it misfires. If I let off then give it more gas it sometimes will get past the shaking. The check engine light came on a few days ago, and the codes said that cylinder #5 was misfiring, and there were misfires detected within the first 1,000 revolutions. I have changed the spark plugs, the coil pack for cylinder #5, cleaned the mass air flow sensor and put dielectric grease on all of the boots and coils. None of those things seemed to do any help. Yesterday, I was driving the truck and the check engine light began flashing. I stopped and let the truck rest for a bit, and then drove it home and its been parked ever since. If you have any ideas about what could be going on, it would be greatly appreciated.

 

What kind of sparks ?

I would try change only spark again..yup try change #5 spark.

Happened to me I changed the spark and its all good.

Jake

 

I took it to school (going through diesel tech school), and we spent about an hour troubleshooting, unplugging coil packs, moving spark plug around and found out that it was the spark plug in cylinder 5 that was bad from the manufacturer. It had a crack in the ceramic. Cleaned the throttle body and changed the spark plug and now she's running like a dream! As a present to myself after fixing the truck, I just ordered a new head unit for the truck and installed red LED's to light up the floor boards inside the truck.

Thanks for the help Jake,

Kevin

 

Awesome! I had this feeling it was darn spark! cuz it excalty happened to me

Must be feel huge releif !!

Enjoy!!!

 

Definitely happy to spend $10 on a spark plug instead of a lot more for injectors or something else!