I've had my 2003 V10 for about 6 months now, and a total of 87k miles on it. I've only driven it about 2k miles since I've owned it. And since I had no way of knowing if the plugs have ever been changed since it rolled off the assembly line, I decided to go ahead and do it.

I went with the Motocraft OEM platinum plugs after reading on here that they seem to be the best, with fewest problems down the road.

I started with #6 and #7 tonight (I'll work my way thru the rest of them this week). I'm not driving the truck on a daily basis so I'm in no great rush to get it done.

Gap is supposed to be .054" and the 2 plugs that I've taken out so far were both .074" -- .020" over. Wow. Pretty obvious they've never been changed before. They look ok to me color-wise, just really worn.

I have 2 question (so far):

1) What impact would plugs .020" over have on engine performance, if at all? I've had no CEL, and I'm running Mike's 5Star tuner. It hasn't been missing or running rough or anything like that. My running around mileage has been ~10mph. So maybe I'll pick up some mileage gains? Maybe I'm just wishful thinking...

2) Is there a general consensus on proper torque for the plugs? I think I've read about 100 posts on torque specs but nothing that everyone seems to agree on. I used anti-sieze and torqued to 100 in-lb. But I think I'm going to go back and tighten them up to 168 in-lb per this thread. I definitely don't want to blow out a plug hauling heavy this summer into the mountains.

Link to [picture of old and new plugs

 

For my money on these Modular Motors this is the best advice/practice I've found so far, quite well sums it up: https://www.ford-trucks.com/forums/1...ed-torque.html Post #2.

I've used this to good success and even passed the info on to others myself. In general its good sound advice, not overly complicated and quite easy to accomplish by most of us DIY's. Here's a photo of my 5.4 V8 plugs after supposedly 63K miles (PO went 100K before changing):



#3 was loose in the head, probably not torqued properly or checked after installation to assure they were still up to spec.

Worn plugs replaced with the proper type/brand and gapped new ones definitely increase mileage and performance. The V10's are a bit thirsty, maybe look into a 5 Star Tune which has legendary following here.

 

132 inch lbs.
https://www.ford-trucks.com/forums/1...-pictures.html

 

I am also in the process of changing the plugs of my 2003 V-10 @ 77,000 miles (the first change ). So far I replaced 7 out of 10 . Two things got my attention immediately .

1- All the old plugs were out of Ford spec (which is 0.052-056 ") . All the plugs I removed were about 0.060-0.062" . In the world of quality control "out of spec" means , reject.

2- All plugs were covered with hardened white ash , presumably because of the additives in the gasoline .

It does not take a rocket scientist to figure out that with these kind of plugs I am getting less mpg , losing horse power and possibly overheating the coils (and shortening their life) due to the higher voltage to create the spark .

I also used a bit of anti-sieze and torqued them @11 ft-# .

So, I am a bit confused about Ford's 100K mile spark plug life , its specification and the engineers who did the actual testing to back up that claim.

PS. I tried dkf's technique - try to replace the boots without unplugging the coils-.
Did not work for me .

 

I'm also one of those not understanding the 100K miles thing---just defies any logic, even the little I have about most things! My own concern beyond their life and ability to still be fuel efficient past 50K miles is the time between changes certainly allows spark plugs to be very difficult to eventually remove.

Not every idea about plugs is perfect and since I'll always check and/or replace my COP boots DKF's idea of not disconnecting the COP's isn't something I'd try or agree with. Some might find it useful and it would save breaking those locking tabs but its just not for me.

Wolfboro I'd re-think that 11 ft/lbs torque setting---somewhere between 21-23 with nickel-based anti-seize should be optimal.

The white ash on your plugs--like mine---might be the grade of fuel being used. Since changing my plugs I'll be adding Chevron's Techron Concentrate about every 3K miles which might greatly reduce or eliminate such deposits. That's my hope anyway.

 

11ft/lbs on a 2003 V10 is asking to pop a plug..

unless u happen to somehow have 3-thread heads, which u shouldnt id seriously consider going back in there and going 20-24ft/lbs..

i did my 03 V10 to 22ft/lbs DRY...

 

I did my 2003 last summer. My gaps were .075 gap. Gapped my new ones to spec and put them in. Didnt notice any change in performance. As for torque specs, I puller on my ratchet as hard as I could. No problems. 2003 was the first year with the full threads in the spark plug holes.

 

I would agree with this. I use nickel base anti seize and torque mine to 22ft/lbs , and re-torque them every 6 months, JUST to make sure.

 

By popping a plug you mean they'll basically fall out, not blow out due stripped threads----do I read that right?

Don't mean to nit pick but that phrase slightly confuses me!

 

both... they will basicly fallout/pop out due to internal combustion pressure..

basicly they loosen off over time and eventualy either blowout under hi pressure when ur driving or they can sometimes decide to just popout/fallout when the engine is first started.

either way its usualy bad news for the head threads by then..

 

I finished my spark plug replacement last night. And went back and re-torqued all of the new plugs to 20ft-lb based on feedback here. I used anti-seize on all plugs, and I plan to re-check them all in a month or so. All of the old ones basically looked the same - VERY worn, and all around .075" gap.

I drove it tonight for about 30 miles or so and the overhead lie-o-meter is showing about a 1mpg improvement. It's been reasonably accurate in the past so I'm hoping its no fluke. And it seems a little more responsive also. Which makes sense.

Thanks all who took the time to offer good, sound advice.

 

My new ignition coil installed 3 weeks ago.
I had a spark plug blow out on my 2000 F250 Superduty V10 gas engine. I repaired it by buying the 'blown out plug kit' and using high temp thread locker to place in the 'rethread piece' where the new spark plug gets screwed in to. Then put in place the new ignition coil (also part of the repair kit). Started up my engine and it sounded ok. Power was not fully optimal but it was better than what it had been before and close to good that I didn't think it was a problem. Then 3 weeks later (today) I took out the coil to verify all is well because I thought I was smelling gas when running the engine. The rubber shaft around the coil appeared disfigured and burnt. Much of the rubber completely missing. See my picture above. DOES ANYBODY KNOW WHY THIS HAPPENED??

 

I've used 26 ft/lbs on my 2V 5.4's SP-479 Motorcraft plugs along with a thin coat of nickel-based anti-seize on the threads for over 10 years now---never had an issue with plugs loosening up in 50-60K miles. I don't let my Motorcraft plugs go longer than the 60K interval BTW.

 

Because whatever kit that was you used, it did not properly seal the cylinder head to spark plug interface. You're getting severe blow-by past the spark plug which has melted the COP boot.

The cheap ($25-40) repair kits have a really sketchy history.

 

Exactly this.
The instant that I saw your picture I figured the ONLY thing that could do that was burning cylinder gasses escaping out the plug hole.