Whats the best spark plugs for my 2009 Ford f350 5.4l gas engine. I am trying to improve mpg,s

 

This is the f-150 forum. You might get more answers in the Super Duty forum.... But to answer your question, the stock Motorcraft platinums are best for the modular motors. They don't like anything else except Autolite (same thing), especially not Bosch.

 

I replaced mine ('09 5.4) a couple months ago. I went with the Motorcraft...I believe they were SP509. So far so good. Do you have the one-piece extended deep well socket. They're way the heck down in there, but at least they're not the ones that break off. (04-08) Not sure how many miles you have on the truck, but a few days before I changed mine, I ran a can of seafoam through the gas, and I pulled the coil packs off and gave each plug a shot of penetrating oil, then put the coils back on. (took about a half hour, but well worth it) A few days later I changed the plugs with ease. The Seafoam removed the carbon on the inside, and the penetrating oil removed the crap on the outside. Be sure to use an air hose to blow all the crap out of the wells, BEFORE you pull the plugs out, that way no crap gets in the motor. Should take about an hour if all goes well.

 

Thanks for info

 

Huh? Where did you get your info from? Iridium plugs take less energy to spark and they can usually jump a longer gap without sacrificing power or performance as they wear. Among other things that platinum's don't do. Just google search it.

With that said, get NGK iridium 372 plugs off RockAuto for only $6.80 each OR the Champion iridium ones for $5 something with a rebate right now. I have the NGK's in the F150 & Ranger, and Denso in my custom built Cobra engine and would never turn back to platinum plugs.

 

Numerous Ford technicians, independent mechanics, parts suppliers, friends and personal experience. I guarantee your iridium plugs won't go 100,000 miles, like the platinum plugs are designed to. I run a hotter plug in my Mustang, but it doesn't have a modular motor. I can Google anything that counters your claims. Don't believe everything you read on the internet, especially when it comes to power claims, mileage improvement, or increased durability. (cough, cough, K&N, cough, cough, Cold air intakes, cough...) For a stock motor, keep the stock plugs or you WILL have issues.

 

I used to be a Ford mechanic until I joined the USAF. No one I ever met said platinum's were better, but we always offered them to the customer because it was OE. I've never had issues with any of my engines while running iridium. And yes you're right, some of them wont last 100K miles but I'm a firm believer in checking them every 25-30K miles. Also, my Cobra engine is a modular engine (4.6 32V) and almost all of us run iridium or copper plugs.

Just depends on what you're looking for, your application, and if you like to do maintenance on your own vehicles in my opinion. If you like to set it and forget it for 100K then yes you're right, go platinum.

Off topic, but I noticed your signature lists an Auburn diff. How do you like it over the stock limited slip? Is it easy to change the clutch packs, for lack of proper nomenclature?

 

I have had problems with copper and iridium, before, during and after my time in the Army, getting thrown out of Air Farce planes. Some in under 5,000 miles. Technicians are the people that I have spoken to whom stated that the Platinum plugs work best, not mechanics (I'm sure you know the difference).
The Auburn works way better than the stock traction lock differential, though it is not re-buildable like the stock unit. Once the clutches wear out, the unit must be replaced. I've put about 40,000 miles on that unit with quite a bit of off road use. No complaints.

 

Moving to general automotive discussion.

 

+1

The problem for the aftermarket is that stock is so good today. This is not 1970 when Ford and the others pinched pennies while not really understanding combustion science. The OE designs today place the spark at the exact position in the combustion chamber and fire at the correct voltage for the electronic ignition system to deliver the most energy (not voltage) to reliably fire lean mixtures.

Please especially dont fall for the "miracle" spark plugs like E3. J C Whitney catalogs used to be full of junk like this if anyone is old enough to remember. E3, BTW look like a cheap copy of a 1990's BMW plug design that has long been abandoned by BMW and its OE suppliers, Bosch and NGK.