Got warm enough on Saturday to pull the truck in the garage and work on it. Turns out I had two plugs with hairline cracks in the insulator. I don't what happened, probably over torqued them. So I made sure I used anti-seize and was real careful this time. Gotta love the back plug on the passenger side! I swear to god if I ever meet an automotive engineer I'll break the little nerd's pencil neck.

 

IMO stock plugs for a stock motor. And again IMO for a power adder a Denso IT series.

As far as testing. No one here has done anything more than subjective "testing". I have my view points because I look at two things. 1) Value. The stock plugs for our rangers are pretty good compaired to the aftermarket offerings **for the same price**.

I also have pushed stock engines for well over 20 years. Turbos, SC, Nitrous.. you name it I've done it on stock blocks. And in that time I've found the NGK TR6 to be about the toughest plug there is. But it'll miss fire at ldle straight out of the box! Put them under a load and they smooth right out. I've even run them very lean. As well as trials of cutting the ground strap back and such.
If a guy is willing to spend a lot of money.. the Denso IT series is a very smooth plug that wll also take some serious pressure and heat. (have them on my 800hp SC & Nitrous'ed Lightning)

Rich

 

LOL.. well there are several things you ought to know first.
1) Some of us aren't so little.
2) This "issue" is so typical of what we have to deal with. Mr OEM manager / sales & marketting weenie says to take a engine compartment / HVAC design from years gone by.. and mate it with a engine that was not meant to be there to begin with. We do the best we can with what we've been given.

Rich

 

To all of you who actually tried to help I appreciate it, I really do. Generally this site is a valuable source of information. However, to those of you who used this forum as a soapbox to present how "knowledgeable" you are without presenting much helpful or pertinent information. I really don't know what to say besides that you really need to find some other place to find value in yourself.

 

What's even worse is when WRONG information is posted!!

 

What's the proper gap for Autolite plugs, 2003 4.0???

..and I want the RIGHT information!!! lol

 

The correct gap is 0.054"

 

I used Autolite XP this time, gapped to .065 The computer at the parts store said this was the proper gap for that plug in that engine. When I got home I double checked on the Autolite site. Although it may depend on what style of autolite plug you are using.

After doing some research I found that the gap is more dependent on the plug than the engine. The "e" code is for the SOHC engine and from what I found the "x" code is for an OHV engine. Then again when it came to the engine code I did find some conflicting and rather vague info regarding what it means. All I know is that I have the "e" engine code. I found this out by inputting my VIN number into the Motorcraft site. From what I can tell the engine code is the 8th letter/number from the left on your VIN number. Don't quote me on this as I'm not positive.

Again the issue I was having wasn't because of improper gap. I checked and the NGK plugs I used were supposed to be gapped at .052-.054" This issue was that I probably over-torqued the plugs and cracked the insulators. Reason 1,495 why I like working on diesel engines more than gas engines.

I've actually been thinking that it would be a cool project to drop a diesel motor into a ranger. Something like a JD 4045H, nearly 400 ft-lbs of torque would be pretty sweet. I don't know if you could even wedge that engine into a ranger. Maybe something I should research a little when I get some time.

 

In my experience over torquing a plug doesn't crack the porcelin. Usually the aluminum in the head will yield before the steel in the plug will.

I've found that cracks usually come from the factory or from someone dropping it. There is also a possibility of someone trying to gap them and pushing off the center electrode.

Rich

 

I think the Autolite site information is wrong. It lists engine code "E" as a SOHC 4.0L, and engine code "X" as a DOHC 4.0L (which doesn't exist in a Ranger). The Autolite site also lists the plug gap of 0.065 for both "E" and "X".

The 2003 Ranger owner's manual, however, lists 0.052 - 0.056 for the 4.0L.

So, I think the correct plug gap is 0.054".

 

Well I neither dropped the plugs or pushed off the electrode when gapping them and I don't know exactly why they cracked, they just were.

 

Yeah the information floating around is a little convoluted. The manual says gp to .054 but it also says to use Motorcraft plugs. The Denso site says to gap at .045 for their plug. The Motorcraft site says under the parts listing for their spark plug to gap at .054 yet if you click on the specifications of the plugs it says to gap at .065. The Autolite site says to gap to .065 I used autolite plugs gapped to .065 and the engine runs great. Good enough for me, I'm not a tuner, the truck is my daily driver/hunting/fishing truck.

 

Check the 8th digit of your VIN. Guaranteed it will tell you which engine you have. Sorry for not seeing this sooner, or I would have cut the drama and answered your damn question!

 

You do realize you're responding to a 14 year old thread.