I had the same thing last fall on a run to Mississippi to go adopt our dog (ETA: at about 80k), of course it happened on a trip hundreds of miles from home on a weekend... Nursed it back home and my trusted local shop replaced the plugs and also a couple of the coil packs.
@JRB explained in another thread here somewhere I read that the way (these?) modern turbo engines can optimize higher octane while being able to tolerate lower octane is to be tuned to exploit the higher octane but monitor constantly for signs of lower octane, and even if it happens instantaneously it happens, and in those instants degrades the plugs. I have the 2.0EB in my Focus ST and the 3.5EB in my truck. Before I would run regular in the truck, and would bounce around in the car. If I was on a road trip in the car and I was buying a tank of gas I was going to use up in the next few hours on the highway, I would just cheap out, and this was probably the worst thing I could do. Then one day when the car was only a couple years old I was in STL in the middle of summer, sitting at idle while I cooled the car down while I entered my notes from my sales call and my damn near new car just died. Fortunately, since I was far from home in an unfamiliar city it fired right back up, but when I did some research I was stunned to learn that at 35k-40k I was already probably overdue for plugs. Since then I have been running mid-grade in the truck and 93 in the car, and when it does the little bobble at idle I take it as a sign to order a set of plugs.
Yeah, don稚 forget to change the Ecoboost plugs at 60k mile intervals.
#RESIST
The grounding strap can move with age or detonation, I've seen plugs go wildly wide in gap and tighten up to damn near shut. A wider gap will generally run better so long as the ignition system can keep up. With turbocharging it's easy to cause spark blowout under high load, so high powered turbocharged engines run a tighter spark plug gap to prevent it. On heavily modified turbocharged/supercharged cars I've ran as tight as a .018" or .020" gap to prevent spark blowout.
Yes, these engines have pretty damn good knock sensors and the PCM monitors for knock events. Based on the knock count (how often these knock events are happening), it will pull back ignition timing advance and add fuel until it quits knocking to save the engine. Ford's drive cycles will self-learn and keep that all info for the most part, so it's not uncommon for nearly identical Ecoboost trucks to see a 2-3 mpg difference between an aggressive driver filling it with goat piss 86-87 octane and a gentle driver filling it with 91+ octane.
These learned fuel and spark trims will very gradually attempt to lean out the fuel and advance the spark for better power and mpg, but generally speaking if you've been feeding it 86 octane and want it to run as best as possible on 91+ octane, you'll need to reset all those fuel and spark trims in the PCM so it can learn all over again. Otherwise it'll run 91+ premium quite happily but it'll be on mapping that was playing nice with 86, so the benefits of premium would be minimal until the PCM re-learned and that can take a long time with Fords if you don't reset them.
Then it takes a long time to get through enough drive cycles for the PCM to fully reset.
Overall I'm a big fan of Iridium spark plugs for applications like an Ecoboost, as well as an aggressive replacement schedule. For the most part coil packs will last 2-3 sets of plugs at a minimum, so it's best practice IMHO to try a set of plugs first before throwing coilpacks at a vehicle with ignition issues.
I did some research and both the F150 forums and my tuner (5Star) recommend the iridium SP550 pregapped at .028 Ford Motorcraft plugs. Mine are out for delivery and I知 still not used to pregapped plugs, so I値l be checking them before installing
#RESIST
Depends on the tuner and the exact truck. For a canned tune in a preprogrammed tuner, we had good luck with SCT but things may have changed in the ~5 years since I left that profession. We also used Diablo on some Dodge applications to good effect, they could also do Ford but our resident tuning guru preferred SCT for Fords not being custom tuned directly via HP tuners.
Generally speaking, most of these tuners have a 'performance' tune and an 'economy' tune and some misc middle-ground tunes. Be careful that you're using the fuel the tune is expecting, as most tunes especially the 'performance' tune will expect 91+ octane 24/7. The PCM will still save the engine based on knock count but a more aggressive tune will beat up the pistons in those instants before the PCM pulls back timing and adds fuel.
Be very careful when measuring the gaps on Iridium plugs, the electrode is much more delicate than typical platinum/copper plugs and if it's damaged or scuffed in any way that can drastically affect the performance of the plug.
Understood, but does this imply that the baked in tune will eliminate or limit the learning of the ECU? I can commit to the octane, but would like to not be chasing a moving target that is based on what I may have been doing (or not) in the prior months.
Yeah, me too, I have read enough of your posts on the topic to value your input.