VoiceOfReason

They possibly switched to suppressor type plugs.

If anyone is still having issues with NGK or Motorcraft (Ford) plugs, you may want to try the Autolite XP5363 plugs.

Joewee3.5

I've put about 200 miles on the new plugs and have mixed feelings. Mileage looks to be up a little but negligible. The truck idles and runs like butter now. BUT, and this is a big deal for me, it feels slower. I don't know if its in my head but it feels a decent bit slower. Who knows though. All in all I'm happy I swapped them.

VoiceOfReason

I missed the part where you said you use octane boosters. They don't really do anything for you...

The whitish residue on the ground electrodes is normal. Indicates the engine is running stoich or slightly lean (the Ecoboost uses various ultra-lean burn modes.)

Joewee3.5

Then explain the past 800 miles I am up over 1 mpg per tank and that's with over an hour of idle time per tank. I am confident these plugs are outperforming the NGKs. I am at 19.1 mpg this tank and I've only seen that mileage one other time and that was stock plugs with tune.

engineermike

This gets posted from time to time (kinda like the "runs rich during breakin/cold start" old wives tales). I have seen no evidence of either of these in 25000 miles on the wideband.

VoiceOfReason

It's not going to show up on any tuner or sensor display available to the public. Ive stated this many times on here before, you may want to read up on ultra-lean burn engine designs (only possible with direct injection) and stratified fuel charging. This is basically where different pockets within the combustion chamber have various ratios of fuel to air, resulting in varying burn characteristics.

The ultra lean mode will be active at cruise/steady state. How it works is it reduces the injector durations and delays it until the compression stroke, so the fuel charge will be non-homogenous and directly around the spark plug, surrounded mostly my air.

Because this has reduced the power output of the engine, the throttle can be run mostly open which reduces the pumping losses and increases the efficiency of the engine.

engineermike

Oh, I'm familiar with lean burn technology ... learned about it years ago. Problem is, if it were actually running lean it would show up on the wideband...and the wideband says 14.5 at all times not WOT.

C Rock Booster

Denso Iridium Power plugs are the best thing since sliced bread! Had them in my Eco gaped at .033 for approx. 8,000 miles and have had no issues. Won't be using any other plug.

VoiceOfReason

It's not going to show up. The fuel is still being burnt at stoich (14.5/14.64:1), it's just the fuel charge is in a small concentrated pocket around the spark plug, rather than the entire cylinder being homogenously charged at that air/fuel ratio.

The air/fuel mixture still needs to burn in that narrow optimal range (remember liquid gasoline doesn't burn, it is the vapours.) The computer is always going to show you stoich A/F ratio, it is NOT going to show you the lean burn mode because that's a complicated equation of throttle position, load, injector durations and timing, cylinder head and piston head shaping/engineering, intake plenum design, etc. It's not something you bolt on and have a statistical display of without serious complex and proprietary engineering specific to the engine platform (which Ford/other manufacturers engineers most certainly have, and are closely guarded secrets.)

brettd4x4

14.5 commanded or measured? I watch the measured ratio and it bounces around from 14.3 to 13.9. Commanded ratio slightly higher