I was going to do spark plugs today and decided to dig this thread back up in helping me decide what plugs to pick up.

I was going to just go with the Autolite 3923's, since I have a 4.7L Non H.O., so I went to Advance Autoparts website, and they don't even list that plug as an applicable plug for mine, which is a 2007 Flex Fuel 4.7L. I checked the VIN for the H.O. and they still list the 3922 for them, but for me they're showing Autolite 5224 in various models, such as copper (5224), single platinum (AP5224), double platinum(APP5224), and Extreme Performance (XP5224) Has anyone used these?

So now I don't know if I should go with these 5224's or not. I didn't really plan on going with Iridiums mostly due to cost($70-$80), but now I'm wondering if I should based on my tuning and running 91-93 octane all the time. The only Iridiums they show are Champion, Denso, and Pulsar.

I know there are some differences between the Flex engines and non flex fuel, so I don't know if this is why I'm seeing different recommendations or not.

Opinions?

 

I decided to check and see what the truck has in it from the factory and under the hood lists a Champion RC12MCC4.

I cross referenced this with the Autolite cross reference data and the match for it is the 5224 that I mentioned earlier. So I may just go with these.

 

Go with the 3923's. Autolite's part numbers have an ending "4" for the stock heat range, and each number lower is a heat range. By going with the 3923's its one heat range colder and people have gotten the benifits of a smoother running engine.

 

I've ran the 3923's for the last 6 months 5000+ miles and I am happy with them. I'm not saying my truck jumped to life or anything, but they seem to work well.

 

I really cant tell a difference except it does seem a little smoother at idle and during acceleration. It might be in my head though. If there is a difference, I would be the only one who would be able to tell. No one that has rode in my truck before would be able to get in and go "Wow, it feels so much better!"

 

I installed the 5224's as recommended since it's the eqivalent to my stock plug. Truck runs like a champ. I definately need them, I only have 38k on the truck, but they were original and well worn.

 

When I pulled out my stock champions a couple months ago the electrodes were gone in the rear cylinders. Swapped them out and drove about 6k miles. When I pulled them out this time, they were a coffee color gapped at .041-.042 so the stocks do perform pretty well, IMO. Technically you should pull and regap your plugs every 6-9k.

 

Yeah I plan to pull mine after several thousand to see how they look, if they're looking good then I plan to stick with these.