Hello all,
Last few months something weird has been going on with my 19 F150 3.3l. When on the highway under hard acceleration for passing or merging I will at random get a miss fire. I checked codes and I got p301 and multiple random misfires detected. This started a few months ago and seems really random. I have noticed in the last few months a decrease in fuel economy and a really weird idle that is rough at times but again doesn't seem to stick around. I'm at 82000 and nothing yet has been changed. Just looking for ideas or thoughts.

 

I notice a rough idle while at stop lights sometimes. Nothing real bad but noticeable and usually coming to a stop while sitting at lights. Doesn’t happen all the time so don’t worry about it as I haven’t gotten any codes.

My mileage has went down but I added a ARE cold air intake, 8’ rod holder and awing on racks which in combination has effected mine.

 

Its super random for me. I really wonder if the vvt solenoid is sticking or has trash in it. If I drive it hard for a few days it will act normal for a week or two before going back to running like trash.

 

I would start at changing the spark plugs first and then go from there. Good luck.

Tom

 

I would change the Plugs.
The Gaps may be wide, now on winter fuel, and climate changes.
Good luck.

 

Give your MAP sensors and throttle body a good cleaning.

 

Gonna change out the AFE CAI back to stock for the winter so that sounds like a good suggestion. 👍🏼

 

Ended up doing plugs and boots. Some of the Gaps were wild. Back to running great thus far. Hopefully was just the trash plugs.

 

Ecoboosts are notorious for eating plugs. The service interval is absolutely insane for these trucks. I usually half it.

 

Wide Plug gaps will do the misfires.
A change of conditions seems to bring it on when the Gaps get wider.
It seems the plugs are a little on the Hot side of the Heat range in >some engines and causes the Gaps to widen in a shorter time frame.
Selecting a step cooler in heat range can be difficult because Plug heat range info seem not to be updated very often to help selection.
Changing Plugs more often just keeps the engine running better so its a toss-up for the effort.
A way to tell is look at the misfire counts records for each cylinder using a Sanner to see Test 84 history.
Good luck.