I am thinking about changing plugs in my wife's 2006 Mountaineer soon, it has the 4.0 in it. I am asking for some advice about plug types. I was looking at Wal-mart and they have a Bosch Double platinum that says it doesn't need gaped for 4.50 a piece. They also have an autolite(regular plug) for 2.50 a piece. I had heard before that it doesn't do any good to put platinum plugs in engines that didn't have them from the factory. Is that true? Is is a waste of money to put the Bosch plugs in, or would the autolites be just as good. thanks!

 

Its a waste of money to put Bosch plugs in anything, even your lawnmower.

For best results, use genuine Motorcraft plugs. You may ask does it really make a difference? The answer is very very yes.

Your factory plugs are double platinum, you need to replace them with OEM spec double platinum or finewire iridium enhanced plugs.

Bosch is about rock bottom in industry standards. Its what you get when you take a German engineered product, then have it built by the low bidder.

If you don't want to get Motorcraft, then use Autolite XP iridium plugs, or NGK Iridium. You are wasting your time and money with anything else.

 

Thanks, shows what I know. I thought Bosch was a good brand. I did see that that advance sells motorcraft plugs that they say are for the 4.0 for about 5 bucks a piece or so. I will probably just go ahead and get them then. I wanna make sure I got the right number though, does anyone know the part number for the motorcraft plugs that the 2006 4.0 takes?

 

+1 for NGK Iridiums.

It's a pity but the Bosch plugs really aren't any good.

 

I've had good luck with Iridiums in a 5.0 Mountaineer, a 4.6L Mountaineer, and my current 4.6L DOHC Aviator. I went with the plug number listed by application on the auto parts store's website.

The Motorcraft part number may be listed on the emissions label under the hood of your Explorer. You can't necessarily go by the number on the plug you remove. Ford often used one part number for Bank 1 and a slightly different number for Bank 2. The difference was where the plug had the platinum contact. Replacement plugs, as mentioned above, were double platinum so the same part number worked in both banks. I'm not sure if they still were doing the different part number trick in 2006.

-Rod

 

Just an update. I did the job this morning. I went ahead and put In the NGK iridiums. Got them from advance for 6.99 a plug. For those of you who have changed these you know that the passenger side bank is a PITA even with the breathing tube removed from the throttle body. Anyway, took it for a spin and it might be imagination but it seems a bit more responsive and peppy. Won't know if it helps fuel mileage or not for a bit. I am hopeful it will but not really expecting a huge gain. Anyway, that's my story, thanks for the advice guys!

 

As a general rule of thumb, platinums in vehicles with multiple coils/coil packs, and regular plugs in ones with a distributor. A platinum plug requires a higher voltage to fire, and a single coil may struggle with this, plus it puts more stress and energy through the cap and rotor. A good copper plug is best with a distributor, unless a platinum plug is specifically called for by the manufacturer.
Don't use a platinum in a small engine, they don't have the ignition power to make it work.

 

That is what NGK claims but then plug manufacturers have being saying stuff like that for years.

They are supposed to be high performance plugs.

The needle point does unshroud the flame kernel and that should allow a more efficient flame propagation, whether or not you'd feel that I don't know.

Anyway, new plugs always feel better.

 

Well drove it this morning again to church and to get groceries and it is not my imagination, it is definitely more responsive. Hopefully it will help mileage a little too, but I am satisfied with the improved throttle response. I think the ones I took out were the originals, hard to say as it had 82,500 miles when we bought it, but they looked pretty burnt down.

 

Regardless of brand, there should be an improvement going from an old worn out plug to a new one.

 

Make sure you gap them properly, the blokes on a British Mondeo (Contour) forum say that too much gap will put a strain on the coil pack.
These are the same parts. The same parts.

 

I agree

With Bosch, people are buying the name, they are sourced out to the lowest bidder. Just like Autolite used to be a good brand, now if you get their plugs, they are made in China!

I use NGK almost exclusively in my marine business and I use them in all of my vehicles (even my Harley)

 

Speaking of parts made by the lowest bidder.