How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask C. Walker, Jr. Your Own Question
C. Walker, Jr.
C. Walker, Jr., Auto Mechanic
Category: Car
Satisfied Customers: 711
Experience:  Shop training and experience.
Type Your Car Question Here...
C. Walker, Jr. is online now
A new question is answered every 9 seconds

navigator 2006 5.4 with 100k on it.runs great until on highway

Customer Question

navigator 2006 5.4 with 100k on it.runs great until on highway and hitting the gas. Starts to buck like its not getting spark for a second. Ive replaced 6 of the coil pacs but not the plugs..( they like to break off ) im wondering if a bad sensor is causing the bucking. once it starts bucking i can find the sweet spot on the pedal and it runs fine till i ask for some passing gas filter new fuel pressure control unit. any ideas? fells like ignition is cutting out when demand is put on it.. anyone got the goods on this? thanks chuck
Submitted: 3 years ago.
Category: Car
Expert:  C. Walker, Jr. replied 3 years ago.
Thank you for trusting us with your problem, my name is Charlie and I will be assisting you today.

This is most likely the spark plugs. I have run across this a few times and the system will not produce a check engine light. The only way to really see the codes is connecting a scan tool and counting the misfires on each cylinder to determine which one is causing the problem. You will want to change the plugs out first before anything else. Once you get this done it will most likely clear up any issues. Before extensive testing, it should be noted there are updated spark plugs for this engine that will many times repair this condition and others similar to it. Note in this case, the updated spark plugs resolved the concern. Note, be aware the spark plugs in this engine may break off in the head. Let engine get hot, remove all coils, soak penetrant oil in hole, barely crack loose each plug, then allow to soak over night. The plugs may still break off, but this procedure is sometimes helpful. Below is the updated spark plug.

Let me know if you have any questions, thanks.
Customer: replied 3 years ago.

will get the extraction tool before pulling plugs so the truck isnt tied up waiting when a plug snaps....thanks Ill let you know in a few days charlie.I do have check engine lite on. I clear it and then push it on the highway and i can make it blow code. Ill have the code read and start on the cylinder that misfires..thanks


Expert:  C. Walker, Jr. replied 3 years ago.

Thanks for the reply,

If you run into anything let me know anytime and I will be here to help you out. If you do rate the question you can still always get help on the same problem if needed until finshed.

Thanks again.