5.4L 3-valve spark plug gap?

[762mm]

This has been bothering me since I've put new spark plugs in my 5.4L 3-valve last summer. Instead of looking it up in the user's manual or Alldata, I decided to Google the spark plug gap and a lot of guys on various forums recommended a .054 gap. So, this is what I (carefully) gapped my Champion iridiums to and put them in there. They've been working great ever since.

However, sometime later I noticed that the recommended gap is actually the factory-set .041 for the "newer" 5.4L. It is confirmed by the user's manual (that I never read, lol). Ooops!


Here are my options :

A) Replace them again and put in a new set, factory-gapped at .041 ;

B) Remove plugs, regap again to original .041 and reinstall ;

C) Leave them alone.


My main concern is squeezing out some better fuel economy (if possible) and also prolonging the coil life. I'm not sure if that .013 will make any difference in the real world, though. So, what do you guys think?

 

[762mm]

Here's the picture of before and after (original plugs vs what I installed). Old one was past .070 on the gauge. Still a big improvement, lol!

 

[TobyU]

I always gap on the tight side of the smallest clearance spec'd.

The gaps always erode with miles.

I pull lots of 2v ones and they are at .068-.072 and they started out at .052-.054 so I set them a tight .052.

 

[762mm]

I always gap on the tight side of the smallest clearance spec'd.

The gaps always erode with miles.

I pull lots of 2v ones and they are at .068-.072 and they started out at .052-.054 so I set them a tight .052.

Yeah, I would have left them at .041, but too late now. Since they are iridium, erosion is not really a concern for a long time.

I was wondering about adverse effects from running .013 too large a gap... for 10 years or so.

 

[TobyU]

Yeah, I would have left them at .041, but too late now. Since they are iridium, erosion is not really a concern for a long time.

I was wondering about adverse effects from running .013 too large a gap... for 10 years or so.

I think it is a little harder on the COPs and your chances of misfires increase as the plugs get older. But is it worth pulling them out? I use the cheap ebay coils with total success so far so at those prices....probably not.
Wait until there is a problem or occasional misfire and then do them and coils.

 

[762mm]

I think it is a little harder on the COPs and your chances of misfires increase as the plugs get older. But is it worth pulling them out? I use the cheap ebay coils with total success so far so at those prices....probably not.
Wait until there is a problem or occasional misfire and then do them and coils.

It's what I figured too... probably best to just leave them alone, until they start acting up. Maybe I'll change them in a few years, if Denso releases the "TT iridium" spark plug for the 5.4L 3-valve (had them on my last Ford, great plugs).

Thanks!

 

[inmanlanier]

100,900 miles and I just replaced the plugs. These new style Ford OEM plugs are excellent - very little wear. The as-found gap was 0.042 to 0.043. If I'd known this I'd have probably kept on driving until misfire. At least I'm good for another 100K.

 

[TobyU]

No doubt. I just pulled a plug out of a 93000 mile 4.6 and it was at .062 maybe .064. It was starting to misfire on that one.

 

[Motorcity muscle]

Must be an earlier plug, just changed mine in '07, tip did not have an adjustable gap.