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The Duratec Sparkplug Sticky

157K views 255 replies 89 participants last post by  Billythakidd1113 
#1 ·
There is too much confusion and misinformation out there, so I'm going to simplify everything.

First off Here's a quick do and don't use
Do Use
OEM Plugs from the dealer
Autolite, "coppers"
NGK "coppers"
Don't Use
Anything made by Bosch
Designer plugs
Autolite Platinums

Secondly, I'm not going to touch Forced Induction, Nitrous, or 30+ hp gains

I'm going to base this off my 2006 D20 (vin N) non p-zev.

The Focus comes with "Motorcraft" Spark Plug made by NGK.
Yours may have come with a DOUBLE PLATNIUM plug.
The reason your Focus came with this type of plug is for 1 reason only. THE BEST SPARK OVER THE LIFE OF THE PLUG it is a tricky play on words but just read it it seems simple enough. They're not making any claims beyond long life. You can expect 80-100,000 miles out of factory plugs.
www.fordparts.com offers the OE replacement for $18.19


There are a few different options available out there. Other manufactures who make a factory replacement, there are cheaper options, and then there are designer plugs.

I'm not going to touch on the designer plugs because if it's too good to be true...

I will say that the Bosch +2 and +4 work wonders, on BMWs from the late 1990's to the early 2000's. BMW contracted Bosch to come up with a plug to help clean up emissions. Bosch, like any smart company decided well heck, we can make a fortune off this. However, BMW stopped using these around 2005 when they released their "N" generations engines. Now BMW only uses Bosch spark plugs in a 1 or 2 engines.

The bottom line is Bosch +2 and +4 plugs will never perform the way they were intended on any car other than what they were designed for.

To begin with there are many companies making a good double platinum spark plug, but I will say that with the double platinum spark plugs that modern cars are designed so tight that you really need to stick with the original manufacture of the plug to have the car running right. There is no government control over the spark plug industry and the thickness of the platinum from manufacture to manufacture is going to vary.

Now onto replacement options.

You're first replacement option is to replace the spark plugs with the ones it came with. In my previous rambling, as mentioned you really want to go with the plugs from the Dealer, yes I know it sucks. But when playing with platinum you're just that, playing. You can try the replacement plug from NGK in the NGK box, but you really don't know if you're getting their 100% quality. If you go to the dealer and buy them in a Motorcraft box you know for 100% fact you are getting the spark plug designed by NGK for Ford. Unless your parts guy is an idiot and there are a lot of them out there, so do your research and ALWAYS ALWAYS ALWAYS go into the parts counter with your vin#.

You're second replacement option is to go with an iridium plug. Iridium plugs have not been around that long, and were introduced to make the longevity of the plug last to a true 100,000 miles. I think we all know someone with 80,000 miles on there vehicle with double platinum plugs and it started running like crap, and the plugs were just worn out.
In my opinion, iridium plugs push the line of designer spark plugs, and only reason I included them is becasue, there are a few manufactures using them now.

Now onto the confusion. Copper spark plugs.

To begin I will only be covering Autolites, however NGK makes a quality "copper" plug as well.

Why copper?
Copper conducts electricity much better than anything else on the market.
Why not copper?
It's life is about 1/10 that of a platinum plug HOWEVER at 1/10th the price, you do the math, if you're time and labor are free you're not really losing anything in the end.

All copper plugs from Autolite, are part #'s A### OR AR###
That's it, if it says AP it's not, if it doesn't have an "A" or an "AR" infront of the part number it's not copper.
We have 3 choices when it comes to copper
The Autolite A104
The Autolite A103
The Autolite AR103

I will breifely touch on gapping after this next rambling.
I always gap my D20 non pzevs at .055"

The A104 is of the factory Heat range, it is considered a replacement plug. You may or may not feel a gain with this, but you will feel your vehicle idleing smoother and possibly a decrease in fuel consumption.

The A103 and AR103 are a heat range lower.

A lower heat range works by allowing the heat to dissipate faster across the spark plug. This is benificial to us.

The advantages of a lower heat range:
lowered combustion temps
lowers chance of pre-detonation
burns fuel more completly, this is the one that makes us power and decreases fuel consumption
lowered emissions
The disadvantages:
There is a higher chance of the spark plugs to become fouled because it is cooler and if you have OTHER ISSUES SUCH AS LEAKING INJECTOR, it's going to cause the electrode to get wet and it will never get hot enough to burn that wet fuel away. If you're fouling a 1 step colder range on your focus, you have other issues going on.

First the A103, a good plug you will notice results from this. Your car wil be quicker, it will idle better and you're fuel conspumtion will decrease.

The AR103 is identicle tot he A103, but it has a groove cut in the electrode and the electrode is nickle plated. It is also way more electro magnetic interferance resitant than any plug out there, which is not benificial to us using coil on plug, but still nice to know if there is ever an EMP attack our spark plugs will still be ok. lol The AR103 will be less prone to fouling and carbon build up, which may results in a little longer life. But the big thing for us is the groove cut in the electrode, the idea behind this is to make a wider flame front and it works well and will make 5hp over stock plugs on a stock car.

On to life and gapping.

If you gap the spark plug to the factory recomendation of .050" you should see 30,000 miles from them, however reducing the gap will reduce your hp gains, as you want the spark to jump as far as possible without extinguishing it's self to create a better flame front.

If you gap the spark plug to .055" you should see 15,000 miles. This is the best compromise in my opinion. The gap make the spark huge and will give you a much improved gain over stock.

You can also gap to .060" however I do not recommend this unless you keep a set of hand tools in your car. This will make a very nice gain, however life until the gap becomes to large is very short. When I ran .060" I swear it felt so much better and was getting around 38mpg highway. However, after 8,000 miles started to misfire. and when I checked the gap they had grown to .062" and i guess .062" is just to much for the coil on plug to handle.

Conclusions
If you want longeveity, go to your ford dealer and suck it up and buy the OE plugs
If you want more power and better fuel consumpion, go with the A103 (or AR103 if you can find them)

Hope you enjoyed. Any questions feel free to PM me.
 
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#122 ·
just a heads up guys.

09/04/03 > 04/05/04 2.3's used the 22 series motorcraft plugs from the factory. i believe these would equate to the 103's.

04/05/04 and newer 2.3's used the 32 series motorcraft plugs from the factory. i believe these would equate to the 104's.

being that my zts was an early model, the only benefit from changing plugs would be to keep the car running normal. i have about 87k on the originals, and there is a minimal rough idle, but nothing i think anyone else would notice. i think i will just replace with oem plugs since i get them for 10% over cost being an employee.
 
#127 ·
A bit off topic:
I have gapped my AR103 to 0.065 a few days back. The engine behaved beautifully, until this one time I needed to reach about 5k while the engine was still cold; it stalled, and I've decided to go back to .060.
One thing I've noticed while gapping it on the first time, was some oil on the threads of two of the plugs. It did not look too suspicious to me then, so I simply wiped the threads off of the oil and put them back in.
But,
Today, I found out that the same two plugs are again covered in oil.
Dose anyone have any insights on the issue ?

Thanks!
 
#132 · (Edited)
swapped in the ar103s today gapped at .055"

engine seems to be running like new (not that it was too bad before) and now it is comparable to my wife's 2010 2.4 vibe with the throttle being a little more touchy at the start, wasn't like that before, it used to be sluggish (most likely because of the buildup/etc on the old plugs)

thanks for the write up!
 
#134 ·
So let me know if I have gotten this wrong. AR103's are the recomended plug gapped to .55-.6, .55 for longevity and .6 for a bit extra power. So my question is if I gap them to .55 how long should I expect them to last? I saw 20K somewhere in here but I didn't see if that was the AR's or A103's.
 
#137 ·
Just put a set of A103's in today, the parts store didn't have AR's, gapped them out to .055 and noticed a good more responsiveness at most speeds. Will probably go with AR's next year when I change them out. Thanks for the info guys.
 
#139 ·
Great Advice!! 70k on my 2006 ZX3, old plugs were clean, showed about 050 gap. Put in 103's at .055. Mileage on first tank was mainly highway, with some city was 36MPG!! This is with the winter blend which has been giving me 30-31MPG. Can't wait for summer, I think if this holds I'll be able to break 40MPG.
Plugs were extremly easy to change.
 
#141 ·
This thread is about performance and i get it.

But i dont want performance. This is my gf car. 2005 ZX5 2.3L. I just want plugs that will last. I want to do it once then not worry again for at least 2 yrs.

Plats last longer than coppers. I will try the AP103s. Any issues?

And honestly, I use NGK in my car. so i really want to use these instead.

Thanks
 
#151 ·
Replaced my plugs today. I stuck with the A104's. I wanted to see if there would be a difference.

Sure enough there was. Idle is a lot smoother, vibration at idle with no A/C on is almost gone.

What bothered me is that when I pulled the old plugs there was a bit of oil in the threads of each one but no where else. I then realized it is more than likely just a bit of unburnt fuel.

I checked the valley's of each spark plug, checked the valve cover gasket, not burning oil. no leaks. Just on the threads. heh.

As to HP gains, I have no idea, but the car is running smoother than it has been since the old throttle body was replaced under warranty last year. We'll see if the issue comes back any time soon. I was really surprised to find the boots completely dry of dielectric grease, but they aren't anymore.
 
#152 ·
Hey ladies?

About to hit 30k on this set of a103s gapped at .055

Still runnin great will swap them out for a fresh set next week. Getting close to 130k on motor. Engine still runs great, but a/c compressor is on its way out and I have an awful clunk in the front end over bumps, I think it's my splash guard and broken plastic.

Still getting avg of 32mpg, but only 12 mile drives now as opposed to my old 45 miles one way to work when I'd get 38mpg.

But I don't drive my car much at all, only in the winter and rainy days as my motorcycle is my obsession now.
 
#153 ·
Just changed out a set of 103s for another set. I probably could've got another 30k on the set that were in there. Gap only increased from .055" to .058". Set the gap at .055" again. On a plus side no oil or any of the sorts were in the spark plug guides.
 
#154 ·
I had three Focus either owned or driven regularly; 02 Wag, (sold ), 00 SE, SPI; 04 ZX3, CAL 2.3 w/ 5 speed. I've probably tired every type and brand of plug over several years keeping track of fuel consumption over a 10k period.

I can confirm that copper plugs do seem to work the best; the trend towards Iridum is fine for long life, but poor for fuel economy. I've made the switch yet again to AR103, which over the last 4K or so have improved fuel economy over the 104's that were tried previously; the highway milage gain seems to be about 1 to 1.5 mpg, depending upon speed. Life of the plug seems to so far about what I expected; estimated to be about 12 to 15k based upon the last check of the gap. I remember when Bosch used to sell silver plugs and they did seem to improve milage even over copper, but haven't seem them in ages....
 
#156 ·
Put in the AR103's over the weekend and I have to say, it does feel a bit more peppy and my idle is much better especially with the A/C on. Before the change I installed the Massive dogbone mount and would get a rough idle but very minimal now! Very impressed. Now we'll see how the MPG does.
 
#157 ·
My car is going to be hitting 36K within the next few weeks. I think I am going to be changing the plugs on it. I have never had a vehicle with 100K plugs that looked good at 40K miles.

I'm afraid to change them though as they are on an aluminum head.

How likely is it that I will strip the head. I'm planning on threading them on with a fuel line, tightening them by finger, then just doing 1/16 of a turn to snug them up.
 
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