rtpjunior

iTrader: (4)

Did a little maintenance on my 2011 5.0 Screw today. Oil change, cleaned my air filter (K & N), checked tire pressures, etc. I've been noticing that my idle was a little rough and i would hear an occasional knock during light acceleration, so I checked my spark plugs. I pulled out a plug, and they looked ok for 30k miles, but the gap was off. The Ford manual states they should be set to .041 - .047. The plug was set to .055. I cleaned it, re-gapped it to .045, and reinstalled it, and checked the rest. All were from .055 - .057. The manual lists this as the recommended gap for the 3.7L motor, not the 5.0. Idle is smoother now, will see if my knock is gone tomorrow. Anyone find the same on their trucks?

gDMJoe

The mis-gap isn't surprising. Plugs are often (mistakenly) installed out-of-the-box without checking the gap 'cause they're gapped at the factory.

NOT!
.

Joewee3.5

Not the best tool choice for the iridium plug. That gap sounds super wide. My EB gap is down to .28 and running great.

rtpjunior

iTrader: (4)

What should I have used?

stein78

Pick up a feeler gauge kit to gap the plugs.

rtpjunior

iTrader: (4)

I have one, didn't think it really mattered. Is there some problem with iridium plugs and certain gap tools?

gDMJoe

That's because the spec' for the 5.0L is different than that of an EcoBoost. DUH!

In general, forced induction plug gaps are less than those of naturally aspirated.

Surprising, given that the spec' is .033-.037 inch and you're over a ¼ inch.
.

Joewee3.5

People still say Duh? Flashback to the 90s. Yeah I know they are diff specs. Still sounds wide. Obviously the .28 was a typo. I meant .028 funny guy.

13Harleyfan

Does anybody use an air gap guage anymore?

kbass24emtp

Well I finally found the time to check my plugs and they were all out of spec. One was right at .050 and all the other were .050+, but under .055. I set them all to .045. I noticed right away that the idle was smoother. Will have to see if it does anything for mileage.