Iridium Plugs and Gas Mileage

[ford46guy]

I have a 6.2L F150. The gas mileage is 15-16ish mixed driving (short trips less). Last Tuneup was about 80K miles ago. Motorcraft specifies a double platinum. Thinking of going with an NGK or Denso Iridium. The Ford Place here advised not to, they said the Motorcraft is application specific for that motor (it has 2 plugs per cyl). They only install M/C plugs or not do the work. I am looking to increase gas mileage. M/C plugs for that motor are also priced almost at the bottom on R/A.

The coils also have an additional inline fuse resistor, maybe that won't work with other plugs?

 

[kschachn]

You’ll never see a difference in fuel usage unless the plugs you’re using are truly crummy plugs. The different plug designs and materials are primarily for longevity. Use the plugs that the manufacturer specifies for the engine.

 

[Dave9]

I agree with kschachn that you shouldn't expect higher fuel economy from different plugs, versus new plugs of same type you already had, but odds are that you would be fine using NGK or Denso iridium plugs that the respective manufacturer specs as appropriate for your engine.

With modern higher mileage spark plugs, I like to replace the plug wires when I do the plugs... unless you put on so many miles per year (or are burning oil so plugs are being replaced due to fouling) that it's not been much over 5 years.

A Ford shop isn't going to want to use anything other than Motorcraft parts when they are available. This leaves one less thing for them to worry about getting wrong, to repair to the manufacturer's spec, no better or worse.

 

[ripcord]

Modern ignition systems are so good that there are zero performance or economy gains to be found until things start wearing out. Iridium plugs don't give better performance, they just last longer.

 

[atikovi]

I have a 6.2L F150. The gas mileage is 15-16ish mixed driving (short trips less).

That's not bad for 5,000+ pound truck. Using different plugs wont get you 20 mpg, or any increase for that matter. About the only thing that helps is the Tornado.

Tornado Air™ — More Power, More Mileage!

Drive 30-60 extra miles or your money back. Order online now!

www.tornadoair.com

 

[eljefino]

There can be subtle differences in how something runs, you can get pinging with poor plugs that will pull timing but not misfire. I don't have your engine so don't have any direct experience. If the shop wants to do that they have a reason somewhere between actual observed science, and unicorns & fairies. If the shop otherwise has a good reputation I'd use them, but not expect much more for MPG.

 

[JavierH19]

You'll only get better mpg's if the plugs were worn to nothing and were beginning to misfire. And that probably isn't enough mileage on the old ones.

 

[ford46guy]

Modern ignition systems are so good that there are zero performance or economy gains to be found until things start wearing out. Iridium plugs don't give better performance, they just last longer.

They are advertised as such.

 

[ford46guy]

That's not bad for 5,000+ pound truck. Using different plugs wont get you 20 mpg, or any increase for that matter. About the only thing that helps is the Tornado.

Tornado Air™ — More Power, More Mileage!

Drive 30-60 extra miles or your money back. Order online now!

www.tornadoair.com

Weighs a hair under 6K. With me, 6155 after I dropped of some scrap :lol:.
I do a 20 mile loop, goes up 1000' with the up and down it is consistently 15.5-15.9mpg.
The cold could drop it a bit. Any idling though KILLS mileage. Also if you drive with sprit, the average moves down to 12-13. The truck has 411hp 420Tq.

 

[SC Maintenance]

They are advertised as such.

The theory is the plug will fire hotter with a more concentrated spark and hence burn the mix better. Both are technically not lying but still wrong.

An iridium plug won't do much extra unless you upgrade your ignition system - primarily the coils, to take advantage of that plug.

Even if you do, on a closed loop control system its going to be held to 14.7:1 stoycheometric ratio by the control system. So a better plug isn't going to burn more efficiently, because the control system already controls the mix - unless as mentioned there was an issue before. If the current plug isn't burning the mix properly you should see that on your long term fuel trims - which might be worth looking at before you do your plug swap - just to have a benchmark.

You can try them, and I am sure you can find an iridium that will work fine - but you likely won't see an increase in mileage any better than new OEM plugs would provide - if either provide any bump at all.

 

[Warlord]

Weighs a hair under 6K. With me, 6155 after I dropped of some scrap :lol:.
I do a 20 mile loop, goes up 1000' with the up and down it is consistently 15.5-15.9mpg.
The cold could drop it a bit. Any idling though KILLS mileage. Also if you drive with sprit, the average moves down to 12-13. The truck has 411hp 420Tq.

This is so upsetting to me cause I only average around 17-18 in my Canyon which has probably 1/10th the capability.

 

[thastinger]

If you pull one of your MC plugs, it will likely have a set of numbers on it that cross to an NGK part number. The MC plugs that my GT500 calls for are hard to get and expensive. I had an old take out set, looked on the base and crossed those numbers to NGK, turns out they are NGK made laser Iridium plugs with Motorcraft written on them.

 

[bobdoo]

Back in the 1970's, I had a highly tuned Yamaha RD350, and a Honda Civic (no way to 'highly' tune that one!).

Both had starting and idling issues. I ended up replacing the coils with high-performance parts, and when that didn't solve the issue, I experimented. I found that cutting the side electrode shorter, so the arc was at an angle to the cylinder axis, resulted in *much* better starting, and better idle.

Given that result, I believe that thinner electrodes (which block the flame kernel less) should result in somewhat better charge burn. Although the tech, and the understanding of ICE is so much better now, my 'better' might be microscopic.

 

[ford46guy]

If you pull one of your MC plugs, it will likely have a set of numbers on it that cross to an NGK part number. The MC plugs that my GT500 calls for are hard to get and expensive. I had an old take out set, looked on the base and crossed those numbers to NGK, turns out they are NGK made laser Iridium plugs with Motorcraft written on them.

I think the NGK is only iridium. The plug in the 6.2L (physical dimensions) seems to be used in tons of applications. The 6.2L specs double platinum, but an Iridium plug crosses to some 3.5L motors (and GM too).

 

[ford46guy]

This is so upsetting to me cause I only average around 17-18 in my Canyon which has probably 1/10th the capability.

Rated to tow 11.1K, but it is still a 1/2 ton.
This a round trip, 1500' up and down, some idling. I still think with better plugs it can get more mpg.

 

[kschachn]

Rated to tow 11.1K, but it is still a 1/2 ton.
This a round trip, 1500' up and down, some idling. I still think with better plugs it can get more mpg.


View attachment 146466

Based on the responses in this thread, what would give you that idea?

 

[ford46guy]

Based on the responses in this thread, what would give you that idea?

Marketing, but I guess it is all hype. There are also Ruthenium plugs.

 

[kschachn]

Marketing, but I guess it is all hype. There are also Ruthenium plugs.

Yes. But as noted that’s for longevity, not increased fuel economy. Again unless your plugs are severely worn and causing a misfire then you will never see a gain. It just doesn’t work that way.

 

[heavy260]

I wouldn’t trade the MPG for cam phasers or AFM.

 

[Davejam]

I mean fuel economy on day 1 vs day 1 is not the question right?
At 50-90k miles what's the difference in double platinum vs. iridium?

NGK says the following: So, not much difference?