Misfire at wide open throttle

[SteveMax15]

2015 Expedition Limited MAX with 60K. 3.5L Twin turbo v6. 6 speed trans.

Prior to a long trip i replaced the oil and filter after only 3,000 miles, and the engine air filter which had maybe 10,000 miles on it. The air filter, the old oil were not too bad. Between snow trips and trailer towing, "big blue" works pretty hard and I keep up on oil changes, brakes, tire pressure, etc.
Heading out on the first real drive after oil service, The coil pack went out on Cyl #1 and my OBDII tool showed a P0301 code (CYL #1 misfire). I was down to one cylinder and we limped home on 5 cyl. We stopped into my local auto parts and bought a coil pack. I swapped the original COPs on 1 and 2 and confirmed a P0302 error (my problem moved from cyl 1 to cyl 2 confirming a failed COP pack). I replaced the pack and cleared the codes and we headed out on our trip with the engine running smooth. I'm quite certain that COP was bad.
On our trip (day 2) we were heavily loaded but not towing. Accelerating uphill at WOT at 4500 RPM the engine stuttered and threw a code. P0305 and P0304. Misfire on cyl 4 and 5. The problem went away after we pulled over to read the OBDII system. I've reproduced the problem several times now. The misfire is typically registered on different cylinders now. and I'm starting to believe it's a fuel starvation issue at WOT.
Fuel starvation is a good guess and an expensive fix on this car. I'm here to ask a couple of questions before I pursue an expensive fix.

1. Do I understand correctly the fuel filter is contained in the fuel pump INSIDE the gas tank? The F150's of this year, engine, trans all have an external fuel filter... but the Expedition does not. Can someone confirm?
2. Could I have introduced a problem with noob-service mistakes doing my first ever air filter change? I pulled the MAS O2 sensor out to change the air filter. It's running fine at low throttle. I dunno, I'm hoping for an easy fix. I should just recheck all my work here. It's weird that all was well until I did an oil and air-filter change. Right?
3. Are there other things to check first? Exhaust O2 sensors? PCV valves? Wiring?

... any thoughts on how to troubleshoot this better are appreciated.

 

[maxxplatinum9137]

1- yes good luck changing that out
2- if you’re referring to the sensor just upstream of the air box that is only an air temperature sensor, check Tom make sure you replaced it in the correct orientation. Yes it does need to sit a specific way.
3- spark plugs need to be changed. Depending on your long they’ve been in and how much you tow, I bet you’re having spark blow out bc of how wide the gap has gotten

 

[99WhiteC5Coupe]

1. The fuel filter is contained in the tank, part of the fuel pump module.

2. Why did you remove the 02 sensor to change the air filter? To change the air filter, you simply unplug the sensor connector in the duct, then remove the lid and change the filter (and reconnect the plug).

3. The PCV is in the right (passenger) valve cover. To remove it, you remove the vacuum hose - and unscrew it counter clockwise.

I bought my 2015 Expedition Limited 4x4 new, and when I changed the spark plugs at 45,*** miles (based upon advice on this forum), the plugs were black with the gap burned / opened beyond the gap specification. I always use Top Tier fuel and have never towed.

You may want to install new MotorCraft spark plugs.

 

[LokiWolf]

I 100% agree to swap plugs. I also would look to see what the gap is on the ones you are removing!

 

[LokiWolf]

1. The fuel filter is contained in the tank, part of the fuel pump module.

2. Why did you remove the 02 sensor to change the air filter? To change the air filter, you simply unplug the sensor connector in the duct, then remove the lid and change the filter (and reconnect the plug).

3. The PCV is in the right (passenger) valve cover. To remove it, you remove the vacuum hose - and unscrew it counter clockwise.

I bought my 2015 Expedition Limited 4x4 new, and when I changed the spark plugs at 45,*** miles (based upon advice on this forum), the plugs were black with the gap burned / opened beyond the gap specification. I always use Top Tier fuel and have never towed.

You may want to install new MotorCraft spark plugs.

The ONLY thing I disagree with in this post is the Motorcraft plugs. The current replacement from Ford for what originally came in these motors is COMPLETE crap, and not the same quality. Many experts agree. I could go down the part number rabbit hole, but just take my word for it. What the parts counter will give you, is crap.

This is what I recommend:

Set of 6 NGK LTR7BHX (95605) Spark Plug | ZFG RACING LLC

NGK Ruthenium HX is designed for newer engines which demand high ignitability. Projected Square Platinum Electrode (PSPE) design promotes spark energy concentration and ignites a wider range of air-fuel ratios, offering improved performance in rich or lean engine conditions. 0.4mm Ruthenium...

www.tunedbyzfgracing.com

You can also have ZFG pregap them lower, and if you aren't tuned I recommend the 0.028. It will run better under heavy load.

 

[maxxplatinum9137]

Yeah these ecoboosts love to eat plug gaps quickly. Especially if they are constantly used under heavy loads

 

[SteveMax15]

Thanks everyone who replied. I'll change the plugs soon and report back. Other suggestions welcome.

 

[99WhiteC5Coupe]

Thanks everyone who replied. I'll change the plugs soon and report back. Other suggestions welcome.

You may want to read all the posts in this thread, and replace the lower boots (referenced in post #7): https://www.expeditionforum.com/threads/ecoboost-spark-plug-change.35960/

 

[maxxplatinum9137]

The ONLY thing I disagree with in this post is the Motorcraft plugs. The current replacement from Ford for what originally came in these motors is COMPLETE crap, and not the same quality. Many experts agree. I could go down the part number rabbit hole, but just take my word for it. What the parts counter will give you, is crap.

This is what I recommend:

Set of 6 NGK LTR7BHX (95605) Spark Plug | ZFG RACING LLC

NGK Ruthenium HX is designed for newer engines which demand high ignitability. Projected Square Platinum Electrode (PSPE) design promotes spark energy concentration and ignites a wider range of air-fuel ratios, offering improved performance in rich or lean engine conditions. 0.4mm Ruthenium...

www.tunedbyzfgracing.com

You can also have ZFG pregap them lower, and if you aren't tuned I recommend the 0.028. It will run better under heavy load.

Are these the ones to run in say a tuned 3.5L 2020 f150 also @LokiWolf

 

[LokiWolf]

Are these the ones to run in say a tuned 3.5L 2020 f150 also @LokiWolf

Yes, best plugs on the market in my opinion currently, and MUCH better than the crap Ford is putting in their now.