Ford Racing (M-12405-35T) 10-17 Flex 3.5L EcoBoost Cold Spark Plug Set

After tuning my 3.5 ecoboost and noticing a misfire on cylinders 1 and 5, I moved coils around. The misfire remained on same cylinders and I had good compression so the plugs were not performing well. I bought these due to colder heat range and closed the gap to .028" and the truck runs amazing. It runs smoother than it ever has !!

Installed these on my 2017 second generation F150 3.5 Ecoboost with 93 tune. Had issues with spark blowout for YEARS. Tried a ton of different plugs. Tried gapping at .020... These plugs worked. I ohmed the plugs when I got them to determine if these were knockoffs/counterfeit. All plugs tested 4-5k ohms. Thats pretty standard. And knockoffs wont read consistently. I did gap these to .020. Use the proper gapping tool (ten dollars amazon). No issues so far. 22psi boost.

Good fit and fast shipping

Bought these because I was getting my raptor tuned and the cold plugs are recommended. Great choice

Use to replace my stock plugs at 40k after I got the 5 star tune. This helped stop the little stuttering at idle and the truck runs a lot smoother and cleaner. I got these per 5 stars recommendations as they are high performance. This was the easiest tune up I’ve never done, took me 20 minutes,10 minutes per side. Just make sure to get dielectric grease. I bought the boots but my truck came with a different kind of boot. Only problem is that if one of them breaks or is bad and you need to replace it you cannot buy them individually. Ford doesn’t even sell this part number anymore and you have to special order the spark plug if you need to replace one. The gap is closer is closer to .28 but if you’re tuned that’s ok. Honestly for the price and how fast you get them you can’t beat them, but I did have one go bad and I had to pay $13 to try to find one individually at that point you might as well just buy a new set.

Direct replacement for my 2018 F150 2.7L Ecoboost motor. 45 minutes and the job was done. Make sure you use dielectric grease on the threads of the spark plugs and do NOT overtighten them.

These work great on my 2013 F150 3.5L Ecoboost. No more misfires when running the 93 performance tune. I Highly recommend these if you are running a tune.

Out of the 6 plugs I received, 2 of them were cracked. I wasted hours installing and then uninstalling them after attempting to drive the vehicle to find it misfiring on two cylinders due to the cracked porcelain.