My '14 4x4 3.7L now has 71k plus miles and I'm starting some general PM type work as I have time. I noticed that some people with 3.7's complained of a flat spot during hard acceleration , possibly related to transmission shifting, and mine was no different, but not really an issue for me. I did notice , however, that my trans would shift much better all around if I used higher octane fuel to ward off any audible part throttle spark knock, which started around 50k or so. A tuner is on the horizon for me, so wanted to get it tuned up before taking the next step. Yesterday, I pulled the factory plugs, which looked fine on a visual inspection, and noticed two things. First, they are single platinum,not dual, which is probably not as big of an issue unless you use a waste spark type system, but I think it allowed the second issue to occur, which is with only 71k, the gap on most plugs had grown to over .060". Mileage was good, averaging between 20-22 on mixed driving in mountain type terrain, but had begun to notice a little "bump" at idle sometimes instead of the butter smooth it normally had. Replaced the plugs with Denso TT plugs , which are iridium/platinum (whichever you choose) on both ends. I followed the plug manufacturer recommended .040" gap , which they already were out of the box, and a little dielectric grease on the boots. No more bump at idle , and the "flare" or "flat spot"seems to be better, trans shifts more positively (yes, I did reset computer ) and no real spark knock at light throttle. I know the 3.5EB's have had some plug gap issues , so if you are having any issues with spark knock, shifting or flat spots or flares..checking/replacing the plugs might be time well spent. Now...where's my tuner money ?

 

Thanks for posting this. I have a 2012 3.7 4x4 with about 31,000 miles. I just bought the truck about 2 months ago and might be starting to see that flat spot now that you mention it. I've been thinking about trying a higher octane gas and your post just convinced me it might be worth it. I do use fuel injector cleaner on a semi-regular basis as preventive maintenance. I don't plan on getting a tuner for this one. Don't have the money and I'm concerned about durability afterwards. I need this truck to last long past the payments

 

No problem Pgh Rebel. I mostly thought it worthy due to the many pages of posts in the EB threads concerning plugs , plug life and plug gaps. I realize boosted engines are harder on components in general, but felt it worth mentioning the increased gaps. My gaps were all over the place, with pretty much every one over .060"...some by a lot. I have learned through the years,when dealing with plugs, to follow the plug manufacturers gap ....not the vehicle builders, unless of course you go back with MC plugs as original. I would suggest a dual type plug, either dual platinum or iridium- whichever you feel is best, as having to remove the top half of the intake to change passenger side plugs is inconvenient so lets get the most life possible. If you can find a deal on new coils/boots, why not add them to the mix.

 

I'm not planning on replacing plugs anytime soon but when I do I will probably go with Motorcraft, unless there's another brand that is strongly recommended. Like I said my mileage is still pretty low so I shouldn't need to worry about this yet. Did you have any problems getting the old ones out? Seizing up or breaking, etc. I've heard horror stories of the old 5.4 with it's problems for these issues . My old 2006 had the simple 4.2 liter and it was great!

 

Nope, no problems. The ones on the 5.4 were the two piece design and they were breaking in part because of the two piece design. If I didn't have to pull the top half of intake, it would have been about an hour...maybe less, piece of cake.

 

I thought the plug gap was supposed to be 0.050" or thereabouts...?
I see Motorcraft Finewire Platinum plugs for sale, pre-gapped at 0.050" for $4.97 with $2.50 in rebates per plug.

If these are junk, someone shout it out

 

I think they are fine plugs and will give you no problems at all...just be diligent and consistent on your gaps. The Motorcraft plugs may call for that big of a gap, but the Denso plugs I used call for .040". It has been my experience, that following plug manufacturer recommendations instead of vehicle recommendations, work better on the engines of today with what I consider some very picky designs when it comes to what plugs a particular design likes. Run of the mill old school chevy's and ford's with points ignition were not that picky...but I have seen first hand where a modern design , all else being equal, run better/worse with certain brand and designs. Rock Auto shows everything from Motorcraft with up to a .054" gap depending on model, to champion at .050", to the Denso I used at .040" and even an AC delco at .032". I think the days of generic plug gaps are gone, follow the plug builders info and you will be fine...but that's just my $.02