What spark plugs for 3.0

[RussL]

I was going to change plugs in my 2003 Ranger with 3.0 and did not realize there was two different plugs required.Took one out on pass. side and it is motorcraft AGSF22PGM.Is there a motorcraft plug that you can use for both sides?It still has the factory plugs in it with 110,000 miles on it.Someone please explain.

 

[Dirtman]

Ford did this to save 40 cents... your truck uses a waste spark ignition system which without getting too technical means plugs on one side of the engine fire twice. The side that fires twice requires a double platinum plug (platinum ground and electrode), the other side only requires a single platinum plug (platinum electrode only). So instead of just using 6 double platinum plugs ford cheaped out and used a less expensive single platinum plug on one side...

When you buy new plugs just put double platinums or iridium's on both sides. I don't know the motorcraft part number but it would be an autolite app104 for double platinums or xp104 for iridiums. (Autolite makes motorcrafts plugs)

 

[RussL]

Will the SP-500 from autzone work for both sides?It is motorcraft AGSF22FM

 

[Dirtman]

I do not know, I don't know motorcraft part numbers. If you can verify that it is the DOUBLE platinum and not SINGLE platinum then yes it should work for both sides.

 

[RussL]

What is the difference in double platinum and iridiums?I will just go with the autolites.What should I set the gap on?

 

[Dirtman]

Iridium is just a slightly stronger metal so the plugs will last a tiny bit longer. No difference in performance in any way.

 

[RussL]

Thanks Dirtman for all your help.Russ

 

[Dirtman]

No problem. The gap should be in your owners manual. Double platinum and iridium plugs generally come pre-gapped and should be within spec out of the box but if you do need to make an adjustment DO NOT gap them by wedging anything into them or you will break the platinum/iridium tips off. Use a tool like this to gently move the ground prong up or down without touching the electrode or the plated center of the ground prong.

 

[RussL]

The Ford place wanted $500 to tune up my truck parts and labor!They said they would have to replace the plug wires and coil because of the age of truck????

 

[Dirtman]

Plug wires go bad over time and you're more than likely due if they are original. Coils however don't really wear out, they work or they don't. There is no reason to simply replace them if they are working and visibly in good condition. 500 for a basic "tune up" is a bit much either way unless it's something like a full blown 100,000 mile service including flushing and changing all the fluids in the vehicle from top to bottom. Then 500 isn't really bad at all. All boils down to what they include in this "tune up".

My idea of a 100,000 mile service is oil change and filter, plugs, plug wires, air filter, PCV valve, flush power steering fluid, flush radiator, change differential oil, trans filter and or oil change, new belt, fuel filter, clean MAF, clean throttle body, lube any chassis points, maybe rotate the tires if they are due, adjust the brakes, possibly an injector cleaning or at least throw a can of seafoam at it, and do a full visual inspection on everything else. $500 for that is a great price.

On the other hand, 500 for an oil change, new plugs and an new air filter is absurd.

 

[sheep herder]

For $500, I would hope they're using lube.

 

[adsm08]

The safe bet on their part is to price the plug wires in with the job. Odds are that at least one boot is going to pull away, or one clip come uncrimped if those wires have never been disturbed before. And you can't buy one wire, only the whole set. So if they just price plugs, a wire breaks coming apart, and then you won't buy the wires, either they eat them, or you get a truck that doesn't work right. Either way, nobody is happy.

Coils do wear as well, but usually working with old plugs and wires is harder on them than new stuff, so if there is no misfire there isn't much reason to replace it.

 

[8thTon]

your truck uses a waste spark ignition system which without getting too technical means plugs on one side of the engine fire twice. The side that fires twice requires a double platinum plug (platinum ground and electrode), the other side only requires a single platinum plug (platinum electrode only).

That's not quite how it works. Both sides fire at the same time near TDC on both the compression and the exhaust strokes, so both plugs fire the same amount of times. The problem is that one plug fires backwards. Each time a plug fires it loses a little metal from one electrode - normally that is the ground electrode which has a decent amount of mass to start with. However, on the plug that fires backwards it's the center electrode that loses mass with each arc, and if you put something like a Bosch fine wire plug in there the center electrode will be gone in a couple thousand miles.

The best bet is a plug with an iridium CENTER electrode (some just put a puck of iridium on the ground electrode). Autolite XP103 has that and works great in my 3.0

 

[RussL]

I guess I may have been lucky on changing these plugs.The drivers side was a breeze but the pass. was a little difficult with no real special tools.The only problem I had was pulling off the wire boots without hopefully not damaging them.My truck runs much smother now with no misfires.Time will tell I guess.I bought truck new and has been well taken care for these 17 years.I installed double platinum autolite plugs.I was wondering if I could have went to Ford place and bought exactly what came in my truck?I keep thinking I should have and would have been good for another 100,000 miles?

 

[Dirtman]

That's not quite how it works. Both sides fire at the same time near TDC on both the compression and the exhaust strokes, so both plugs fire the same amount of times. The problem is that one plug fires backwards. Each time a plug fires it loses a little metal from one electrode - normally that is the ground electrode which has a decent amount of mass to start with. However, on the plug that fires backwards it's the center electrode that loses mass with each arc, and if you put something like a Bosch fine wire plug in there the center electrode will be gone in a couple thousand miles.

The best bet is a plug with an iridium CENTER electrode (some just put a puck of iridium on the ground electrode). Autolite XP103 has that and works great in my 3.0

Hence my "without getting too technical" remark...

Also you have it backwards. Single platinum plugs have a platinum ELECTRODE, but a standard nickel ground prong. On those plugs on the batch fired side the ground is what burns up. Double platinum and iridium plugs have a platinum plate on the ground prong that prevent wear when the spark is reversed. (Autolite iridium's only have an iridium electrode, the ground prong is still platinum like a standard double platinum plug).