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Eric, Automotive Repair Shop Manager
Category: Ford
Satisfied Customers: 32343
Experience:  Automotive Repair Shop Manager, Technician
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2005 Ford F150: Lariat..Spark plugs have been replaced but coils were

Resolved Question:

2005 Ford F150 4X4 Lariat 5.4. Spark plugs have been replaced but coils were not. Truck is misfiring - vibration at ~50mph. Ford dealer says cyl 3&4 are misfiring. They want to keep it for a while and run more diagnostics. My brother is willing to replace the coils for me. Question: are the coils for cyl 3&4 accessible for novice mechanic to reach and change? This could save me $250. Thanks.
Submitted: 5 years ago.
Category: Ford
Expert:  Eric replied 5 years ago.

yes, they are easy to get to. they are the 2 most rear cylinders on the passenger side of engine


  1. Disconnect the ignition coil-on-plug electrical connector.
  1. Remove the ignition coil-on-plug bolt.
    • To install, tighten to 6 Nm (53 lb-in).
  1. NOTE: When removing the ignition coil-on-plug, a slight twisting motion will break the seal and ease removal.

    Remove the ignition coil-on-plug.
  1. NOTE: Verify that the ignition coil spring is correctly located inside the ignition coil-on-plug boot and that there is no damage to the tip of the boot.

    To install, reverse the removal procedure.
    • Apply a light coat of dielectric compound to the inside of the ignition coil boots.
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Customer: replied 5 years ago.
Should I be cautious about the distance or amount of driving until I can get the coils replaced?
Expert:  Eric replied 5 years ago.

you wont incur any damage to the engine, but will experience poor gas mileage, the engine misfiring, and if you go more than a month before replacing them, you will need new spark plugs for those 2 cylinders.
Expert:  Eric replied 5 years ago.

if you have a question about the answer, feel free to ask for more help, otherwise you do need to click the accept button to pay for services rendered per the customer agreement as this is a paysite.

If you have a subscription service you still need to click the accept button but you are NOT charged again.

thank you
Customer: replied 5 years ago.
should there be any concern with completing this work in below freezing temperatures?
Expert:  Eric replied 5 years ago.

I would crank engine and allow to idle for about 5 minutes and then turn off and replace the coils. This will warm it up enough to make sure that the wiring harness connectors arent too cold and break apart when you disconnect them. If too cold, they can become brittle and break, so make sure to warm up engine first for a few minutes
Customer: replied 5 years ago.
last question I should've asked sorry bout that... can you give an approximate time estimate for doing the work?
Expert:  Eric replied 5 years ago.

total time to replace those two coils is 20 minutes.