Replacement Spark Plugs
 

The original spark plug used in my '99 Ford Ranger 4.0L was a Motorcraft copper tipped plug. Since then I've used platinum and presently I am using Iridium plugs. I've heard that there are drawbacks in using high performance plugs like the Iridium. Any opinions on this?

I think just about everyone here will say to stick with the stock Motorcraft or Autolite plugs, I am getting ready to replace mine real soon, and will be getting the stock Motorcraft plugs.

Motorcraft always. Fords run really funny on anything but Motorcraft and Autolite. No idea why but they do

I agree with the above posts. Either Autolite or Motorcraft double platinums. At least that's what I run in my 4.0 SOHC.

I use Bosch 4 prong and they work great. Never had trouble with em. Just stick to stock.

Spark Plug
 

My '99 Ford Ranger XLT 4.0L has an "X" VIN number and thus has an OHV as opposed to a SOHC engine. I understand that each use a different type plug. So which one do I use?

Never do what alex98 said. Bosch are the biggest pieces of crap out there

Just use auto lite or motorcraft double plat. And if they are really that junky, why do they work perfectly fine??

I've owned probably 20 words or so. I tried Bosch in probably 5 or so of them because there was some great rebate and the moment i put them in my cars would start misfiring and having issues. Im an OEM guy. Put OEM stuff in and you'll be all good

Very true you can't go wrong with oem, and I usually put oem stuff on my cars. But I've ran them on my old ohv and the sohc never had an issue. They also have a lifetime return policy, I like to experiment with little things here and there.

Well, I now understand how frustrating it can be to buy new spark plugs, after all the research I have done I had decided to use Motorcraft double platinums, however it seems nobody in my town has them, in fact even the platinums are hard to find, so I went to Autozone, the guy told me what they had, no platinums in Motorcraft, so I told him I would
settle for the Autolite platinums, he proceeded to tell me his theory on what should work in my truck and what oem puts in there, I said just give me the platinums, he returns a few minutes later with some autolites, the box says #1543 and it says copper, told him I wanted the platinums, he replies those are platinum, well the box says copper and there should be an AP at the beginning of the number, those are platinum he says, he had already rang them up and swiped my atm card, so i said let me see the manager, even he said, those are not platinums, he was going to get me the platinums, i said no just refund it, which he did, the clerk wanted to sell me what he thought was best for my truck. So I drove a few more miles to another store, the guy got me my Autolite platinums, no problems here, #AP 1543, even the box is blue, instead of orange. So anyways, I got them installed yesterday, which ended up taking all day. but my truck is running great with the Autolites, idles smoother and accelerates smoother, I am happy with them.

I tried the E3's, the plug gave me a problem on the #1 cylinder cause the boot didn't "snap" completely on to it but I trimmed the boot to fit. They have been great so great I put a set in my Mustang.

I recently replaced my plugs and wires. I was going to replace them with E3's but ever person I spoke to mentioned how Fords only like Autolite or Motorcraft. I ended up replacing them with Motorcraft gaped at 0.54(OEM recommendation) and she is running like new.