what type of plugs should I use in a 4.0 engine?

 

Check the owner's manual

 

Check the emissions tag on the engine compartment radiator support.

 

This is one of the few times that you should buy the stock plugs that came in the truck. Aftermarket plugs are no good in these engines

 

what year?

 

As has been suggested, use the specified OEM plugs & I'll add wires, because our "waste spark" ignition system puts them though a double work load.

Read about it here, from our
"Tech Info" thread, located atop this forums thread listing page, lots of other useful info there too.
https://www.ford-trucks.com/forums/1...and-wires.html

Ford now suggests using the newest design, fine wire, iridium enhanced center electrode, with platinum enhanced side wire plug. They are the proper heat range, will hold the specified spark gap longer, fire at a lower voltage & thus get us going quicker on those cold winter mornings, when the battery is at it's weakest & the starer motor, fuel pump & ignition system is having to work it's hardest to start the engine.

At the very least, use the older design specified "double platinum" plugs in your 4.0L.

Autolite makes the Motorcraft plug to Fords specs, so the specified Autolite plug should be ok too.

I'm using the specified newer design Motorcraft "fine wire iridium enhanced center electrode" plugs & OEM wires.

The replacement fine wire plugs have made a noticeable difference in quickness of starts & that makes it easier on the battery, starter motor, computer, ignition system & fuel pump especially on those overnight cold soaked, winter morning starts.

More thoughts for considration.

 

Thanks alot for the info,I was gonna use either the motorcraft or autolite platnuim or DP I think those two would work well in my ranger.

 

Food for thought...I once upon a time many years ago had rebuilt a slant 6 in my 71 Dodge...1st car...anyway...got new autolites and so on...tried everything under the sun...thing ran like crap...horrible...no idle and a pain to get started initially...ended up sticking the same tired old Champions back in it...fired right up, smooth idle...ran like a top...will never EVER buy another autolite plug...absolute junk...

When I replaced my plugs in my 91 I put Motorcrafts back in...which is what came out and was OE equipment too...not a problem at all...91, 3.0 and 276 nearly 277K hard earned miles...remember...do it once...do it right...nobody like wasting money these days especially...



- cs65

 

hey you know I was just saying I miss the slant 6, I had in my 71 duster!! so much easer to change plugs,pvc everything these new engines suck to work on.

 

Classic case of not the whole story. Champion designed the OE plugs for Mopar engines, which means their plug was the right plug for the job. The Autolites may have had the right gap, but the wrong heat range, reach, exposure and displacement. All of those factors matter. Put that same Champion plug in a Ford, and it would run like crap and the Autolites would be great.

Simple fact, most Motorcraft plugs are made by Autolite. Those that aren't are the plugs found in Duratec motors, which are made by NGK. The Autolite double platinum or fine wire iridium plugs are the same thing as the Motorcraft, but they cost a little less because they don't have Motorcraft stamped on them. I use the Autolites on all my waste spark Fords, never had a problem with them. Have had lots of problems with Bosch though.

 

wrong...I have Champions in my 65 FE...runs like a top...

as to which plugs are made by who...how do you know this info ?? I know theres alot of copycat with oil filters...plugs is a new one...


- cs65

 

How do I know this? Motorcraft doesn't make anything. All Motorcraft does is act as a purchasing agent for Ford, and those parts must meet or exceed the OE specifications. Autolite makes the Motorcraft plugs. NGK makes the Motorcraft for the Duratec engines.

Your 65 FE is hardly a Ranger, your example is not a legitimate comparison, the Ranger is far more particular about spark plugs than a 65 FE is going to be. Your vehicle doesn't care as much about things like heat range, displacement or reach. It doesn't have waste spark ignition, or EMI suppression, and probably doesn't have any computers of any kind.

You also didn't specify which Autolite part number you had problems with or the Champions either. In either case, you wouldn't use those plugs on a Ranger. They won't work.

 

I've also had very good luck with the Autolite DPs.

PAWPAW, have you noticed a measurable difference in mileage? Or for that matter towing/ hauling power with the Iridium Enhanced versions?

 

I run Champions in my lawnmower. Awesome plugs

 

I bought my 2000 2.5 ranger new and it had motorcraft DP plugs. Of course Ford changed the specs when it came time to change the plugs and no longer manufactured DP plugs for that truck and referenced a single platinum plug which I installed. I got over 100,000 miles on the original DP's and barely got 60,000 on the recommended motorcraft single platinum plugs. I recently replaced the single D's with autolite DP's so hopefully I will get the same 100,000 miles as the original motorcraft DP's