2021 Powerboost Spark Plugs / Diff & T-Case Oil

[Kmc0929]

Im getting multiple Motorcraft part numbers when searching for the OEM spark plugs for a 2021 Powerboost. Seeing some notes also that the part number changed halfway through the year maybe? My truck has a blend date of 220210314

Anyone have the correct MC part number and estimated quantities for both diffs and the t-case? If the truck has the e-locker and FX4 package, does it require the additive?

in the past I've used a liquid extractor to vacuum out as much old oil as possible from the diffs and t-case and simply refill. I know it's not perfect but is there any thing critical that could go wrong with that process?

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[mredwin25]

SP594 is what I used, no issues

 

[Mosey]

In the PB (and maybe other eco-boosts, IDK) the spark plugs must be indexed to the intake/fuel injectors. That means is the open end of the spark plug electrode must point towards the fuel source or up to 90 degrees either way. The upshot of all of this is the plugs have crush washers rather than being a tapered fit.

 

[Kmc0929]

Oh ok thats good to know...

dealership is saying its the same plug SP-594 for both my 21 power boost and 20 expedition

also says I need

(2)XT-10 QLVC
(1) XL-3
(3) XT-75W85-QL

and
(4) XY-75W85-QL
(2) XT10-QLVC

 

[Mosey]

Oh ok thats good to know...

dealership is saying its the same plug SP-594 for both my 21 power boost and 20 expedition

also says I need

(2)XT-10 QLVC
(1) XL-3
(3) XT-75W85-QL

and
(4) XY-75W85-QL
(2) XT10-QLVC

Honestly, the easiest thing to do is pop one out, take and photo and then get the correct plugs.

 

[Vater]

I had this issue on my 21PB Limited and that midyear there is a change in spark plugs, which may be as implied because of a change of injectors or maybe the change of heads. The suggestion to pop one out, photograph it and then go get some new ones is actually quite valid and the way to get to the bottom of it because Ford in 21 does show two different plugs depending on the motor manufacture date

 

[Vater]

In the PB (and maybe other eco-boosts, IDK) the spark plugs must be indexed to the intake/fuel injectors. That means is the open end of the spark plug electrode must point towards the fuel source or up to 90 degrees either way. The upshot of all of this is the plugs have crush washers rather than being a tapered fit.

I’m not sure what the basis is for indexing in a spark plug to the fuel source comes from. It really doesn’t make sense to me as an electrical engineer. The voltage of that spark jumping the gap is approximately 30 kV. It spreads in a 360° pattern with the exception of the grounding electrode blocking, maybe 10% of that 360° pattern. The discharge of a 30 KV arc should uniformly raise the voltage across the entire 360° pattern grounding electrode or not so I’m not sure what the basis of indexing is because I don’t think it’s really an issue from a physics standpoint.

 

[Mosey]

I’m not sure what the basis is for indexing in a spark plug to the fuel source comes from. It really doesn’t make sense to me as an electrical engineer. The voltage of that spark jumping the gap is approximately 30 kV. It spreads in a 360° pattern with the exception of the grounding electrode blocking, maybe 10% of that 360° pattern. The discharge of a 30 KV arc should uniformly raise the voltage across the entire 360° pattern grounding electrode or not so I’m not sure what the basis of indexing is because I don’t think it’s really an issue from a physics standpoint.

Racers have been doing this for years. I can only speculate but by having the spark open to the incoming fuel may promote better burn.? perhaps the air/fuel in the cylinders is not as uniform as one would expect.

My Evinrude outboard requires indexed plugs to avoid misses and poor emissions (according to the manual).

 

[Vater]

Racers have been doing this for years. I can only speculate but by having the spark open to the incoming fuel may promote better burn.? perhaps the air/fuel in the cylinders is not as uniform as one would expect.

My Evinrude outboard requires indexed plugs to avoid misses and poor emissions (according to the manual).

I understand what you’re saying and I’m not questioning the validity of that in the application you mentioned with your boat motor or even in some racing engine applications. There may be some differences that are dependent on how they’re fueled, e.g., direct or port injection. For example, that F150 PB you have uses port injection along with direct injection. Testing has shown that those port injectors run full-time and our augmented by direct injection during certain power intervals. The function of fuel atomization and fueling method, e.g. port or direct is a very complex phenomenon. I’m not convinced that it is an issue in this application and I don’t think anyone can prove that it is or isn’t because there is no test data or modeling or simulation of the burn pattern in a 3-D simulation that shows that it actually would make a difference. That said, I am not questioning what your boat motor recommends or the fact that historically race motors have talked about indexing plugs. But again the fueling method and applications may be different in which what they’re suggesting may apply while it may not make any difference in a dual injection fueling scheme, like what the power boost uses.

 

[mredwin25]

I didn’t index anything on mine, truck runs great

 

[Mosey]

I didn’t index anything on mine, truck runs great

If you purchased Motorcraft plugs and tightened them to spec then they are already indexed.

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