I agree - sometimes the better & more expensive plug can cause problems if the engine is not built for them. I know for a fact that my wife's mercedes did not like the platinum plugs at all. It misfired like crazy and I had to replace them within a couple of weeks.

 

I read that somewhere too on the HEMI it is wise to use the factory style plugs and to change them at 30k

 

I never had any issuse's when I changed mine out. Thats just me though others may have had different things happen to them.

 

It's amazing that I have another vehicle (Ford Taurus) with 105,000 miles and we just changed plugs last week. 6 plugs. It's a 32 valve engine.

It will take 48 plugs for the Hemi and I only get 90,000 miles out of them. Something does not jive here. I know I have a high performance engine, but "come on"!

I will call them and see what they are going to charge me to replace them. I only have 5,600 miles so far. So it will be a good while before I need this service. I think it's cheaper to raise a kid than it is to own a Hemi! Good thing I do not put many miles on mine.

16 plugs. Who was the genius that came up with that idea?

 

How do you manage to change the plugs under the brake booster??? Do you have to take the booster off?

 

you have to contort your arms and work around it. i usually put one arm over valve cover to hold the extension, and the other arm under booster to turn the ratchet. its a little tricky breaking them loose--lots of pointy stuff back there to stab your hand on.
FWIW: those of you doing plugs yourself on the 5.7, i highly suggest getting a magnectic plug socket. its SO MUCH EASIER not having to deal w/ the old style sockets w/ the rubber boot. i save about 10-15 minutes per 5.7 tune up cause of this.

 

We use two plugs to make sure there is plenty of spark available to ignite the air/fuel mix.

I think the two plug per coil system uses a different polarity than on a one plug per coil engine. The different polarity wears platinum plugs much quicker. Plus, the resistance in the plugs in different. So, Dodge uses copper to get around the polarity/misfire issues, not because they are cheap. I am still researching this. Feel free to Google "platinum plugs misfire Hemi" or something along those lines and you can find some info. There is even information on these forums in the 3rd Gen section.

To those who think these plugs are changed often, try getting a performance turbo car. New plugs every 6000 miles.

 

The Hemi uses a same COP (coil on plug) design as all of the other OEM's, including Ford, GM etc. The difference is, the Hemi fires the first plug on the power stroke and fires the second plug on the exhaust stroke to clean up emissions. Dodge used copper core plugs to save cost when the Hemi engine first came out, hence the 30K mile change intervals. By stepping up to a double platinum plug, the change interval can be extended to approx. 100K miles like most other OEM's.
I put Autolite Double Platinum plugs in my '06 at 30K miles. I have 33K miles now and it runs like it did new.

 

For every person with the Hemi who runs platinum plugs with no problem there is someone who does have a problem. I am still not sold.

Besided, it costs 96$ for 3 sets of coppers, or 90k worth and it costs 126$ for 100k of platinum. It is still cheaper to run copper. I am assuming it is 2$ for a copper and 8$ for a platinum.

 

A spark plug is not voodoo science. If the spark plug is the correct heat range, and is gapped properly before installation, it should perform fine. The coating on the electrode just extends the life of the plug. I agree it may be cheaper to run copper plugs rather than platinum over the life of the vehicle, but I would rather spend a few more dollars and save my knuckles.