rvtrc211v

I recommend gapping them to .45 it made a big difference with my truck. I'm planning on doing the same to my brothers truck as well. it takes about an hour maybe 2.

13Harleyfan

Just got back from the dealer, had my first service and asked them to check the rough idle.
Scanner didn't show anything so no help there. I almost pulled the plugs this weekend but I wanted to give the dealer a chance to fix it.
On a side note, they did replace the battery in one of my fob's for free.
I'll re-gap them this weekend and see what it does.

svt2205

My now expired subscription to motorcraftservice.com was just for the 2011 F150, so I can't offer anything more than what I did. It will be interesting to see if anyone else has access and what it says.

buck91

Wonder if this could be contributing the the "Mode 8" misfires and 55mph shudder. Will have to check mine out this spring.

Raven78

I just regapped mine down from .055 to .047 and still have the 55mph shudder but it idles smoother now.

Jake's Dad

Rock auto tells me that the 5.0 takes NGK iridium IX 6509, or #LTR6IX11.

Has anyone tried these?

JD

Michael Lung

How much torque do you put on the plugs when installing them? 11ft lb?

Ned Fletcher

Finally got around to regapping the spark plugs, I had one at 53, five at 55, and two at 57. After putting them at 45 and doing a short road test, seems that my rough idle is solved.

Of course I broke one of the plugs in the process and had to use zip ties to get it to stay on, but whatever, at least the truck doesn't sound like its going to die at a stoplight.

BobLobLaw

Maybe I need to this. I've had a rough idle on my 3.7 since the day I brought it home. Dealers can't find the problem.

Ned Fletcher

An update:
Went on a drive today, about 150 miles round trip. I appear to be getting between 17 and 22 miles city which is awesome, but i can't seem to get better than 16-17 highway, at times falling to 14-15. Really not sure what the heck is going on here.