Plug gap change between 2011 and 2012 f150 5.0 lit

[97f150]

Anyone know why the plug gap on the 5.0 F150 was changed from 0.041-0.047 in the 2011 trucks to 0.049-0.053 on the 2012 and up trucks?

Long story short, my truck had been having a rough idle situation. I googled and searched on some Ford forums I'm a member of and found that some trucks had wrong sized plugs installed from the factory. I checked my plugs and found them to all be at 0.057. I asked the proper gap on a forum as I couldn't access my manual at the moment and was given the 2011 gap spec. I recapped to 0.045 and reinstalled. The truck idled better and I considered it a success.

Recently though I read a thread where the 2013 5.0 gap was 0.049-0.053. I became curious and checked my manual. Indeed it does list the gap the same as the 2013. I checked with a neighbor who has a 2011 with the 5.0 and his manual lists the gap as 0.041-0.047. Was wondering if anyone knew why the gap was changed.

I will change my plugs and have the manual listed gap set in time, but ironically the truck seems to run better with the smaller gap.

 

[901Memphis]

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=3090959

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=3092014

Here's some demi relevant information

 

[97f150]

Very good info, thanks for sharing!

 

[97f150]

I replaced the plugs today with Bosch Iridiums. I know Bosch is typically a no no for spark plugs but that was all I could find. They were all gapped at .044, so I set them at .049 and slapped them in. Again I marvel at how easy it is to access the plugs on this engine with removal of anything, so if the Boschs give me any issue it won't be such a big deal to swap them back out. I was a bit nervous with the Motorcraft plugs after regapping and bending the electrode around on plugs that have already been through many heat cycles. Time will tell I guess. Thanks again for the link 901 Memphis.

 

[buck91]

Factory plugs were over. 055 at 48k miles on my 2011 with frequent misfires on cylinder 8 showing through mode $06 (no see). Replaced with autolite iridiums tapped to .044 and mode $06 is clear.

FWIW #8 plug was significantly fouled compared to the rest, Gained a full 1.5mpg. I will be pulling #8 in the near future to check its condition (before factory powertrain is up).

I wonder why they increased the gap spec?