I changed the plugs on my new to me truck today, 2009 FX4. Plugs are original Motorcraft plugs with 113,800 miles on them. The truck ran & idled just fine with no hesitation or misfires. It seems that non-OEM plugs have a recommended gap at around 0.044" but OEM is 0.041". The original plugs were all north of 0.050" and most were in the 0.055" range. The finewire tip was MIA on all of the plugs. I think 100,000 service on these plugs is too much. I would say that 60,000-70,000 would be a good time to change them.
R&R was very easy on the passenger side. The only real 'tough' one is the rear plug on the driver's side. I replaced them with OEM Motorcraft SP-509 plugs gapped at 0.041".
The truck definitely starts quicker and has better throttle response. I was surprised at the difference.
Sorry for the picture qualify, my iPhone 4S needs to be retired.
R&R was very easy on the passenger side. The only real 'tough' one is the rear plug on the driver's side. I replaced them with OEM Motorcraft SP-509 plugs gapped at 0.041".
The truck definitely starts quicker and has better throttle response. I was surprised at the difference.
Sorry for the picture qualify, my iPhone 4S needs to be retired.