SkiSmuggs

I had the dealership replace my SP-528 (gapped about .040) at 41,000 because of missing while towing. Two of them had no center post. 17,000 miles later it was starting to miss while towing again and Torque Pro showed misses on Cyl 4, so when I took the truck in for its 60K, I had them change the plugs again. Like the first time, I supplied the plugs and checked the gap, .031 the first time and set them to .028 this time. First tow after that it was even worse. Now I had missing on 3 cylinders, so I pulled those plugs to check them. After just 400 miles, they were so tight that it hurt my hands to pull them. They were gapped at .031, so I suspect they used plugs from stock and placed the ones I supplied in stock when they found them on the front seat. It appeared that the porcelain was slight buckled where it met the metal, but I didn't have replacements so I re-gapped and torqued to 11 ft/lbs as specified by Ford. A spirited test drive with uphill accelerations showed cyl #4 was still missing.
Got 6 new plugs, gapped one to .028 and replaced #4 and the missing was gone. I will replace all 6 because I think they will all start missing due to over torquing by the dealer. I called them to explain the problem and they admitted to tightening them to prevent "blow out" that they had heard about. I explained it was spark blow out caused by large gaps and not plugs blowing out. LOL! I emphasized how critical the Ford torque spec is and he promised to pass it on at the tech meeting.
The moral here is that not all techs know what they are doing with the Ecoboost, that probably 80% of Ecoboost problems are spark plug related even if the dealer just replaced them. Even some of the "condensation" issues have been resolved by CORRECT spark plug replacement and gapping to .030.
I will not have the dealer change my plugs again.

Kenferg1

Get the MSD plugs. Beefy center post, gapped at .031 in the box, and the ceramic is stout. I replaced mine two weeks ago and am very happy so far.

SkiSmuggs

Thanks, I read that, but I have my second new set of SP-534s that I am installing myself to see how that works out. The tip on those MSD plugs looks promising. What is the part number for those?

tcp2

Does NGK make an iridium plug for the ecoboost? I have had great success with NGK iridiums in my vehicles over the last 10 years. currently have them in my 2009 Screw and the OEM ones at 90k miles in our sienna. The sienna is rated for 120k miles before replacement and I pulled one out the other day. Perfect gap and, other than a slight bit of greying in the body, the electrodes look perfect.

Looks like Denso makes an iridium:

http://www.rockauto.com/catalog/more...027&cc=3000987

SkiSmuggs

Yeah, NGK makes the Motorcraft iridium SP-534 plus their own. The turbo engines are a LOT harder on plugs, especially if you tow heavy.

Kenferg1

The MSD part number is 3743. The plug number is 5IR6Y. (edit) I got mine from JEGS. Price at all of the places was the same, but JEGS shipped free. In fact, they came direct ship from MSD in El Paso.

I tend to believe that the thin tips on the standard plug is having a hard time under boost. For those that tune, it is probably much worse, thus the need to gap down to .028-.030 to get consistent ignition. In the MSD video as the pressure rises in the test cylinder resistance rises as well. The lack of surface area appears to cause weak arc until resistance finally becomes to great for the electrons to jump. It just seems to make sense that given the level of voltage that the coil packs supply that a larger surface area on the tip allows for greater electron transfer and so a stronger arc.

Anyway, I'm glad that I changed, and I'm looking forward to towing with these new plugs.

Kenferg1

Your Sienna isn't under up to 20# of boost. Most of the guys that are tuning like the SP534s gapped to around .030.