Truck began to randomly start to misfire. Original threw code for multiple misfire.

replaced all plugs and coils. Changed at filter, fresh oil.

seemed to be running fine, today drove about 5 miles to work, ran fine until I got to lot. Misfire started. Would misfire unless I was accelerating. Engine stalled, but immediately fired back
up. Parked and let it rough idle hoping for a code, nothing.

turned truck off, thought I saw check engine light come on and immediately restarted. Running perfectly fine…

any help would be appreciated.

 

What year is the truck? What brand of coils did you use? Missing at low rpm and not missing when you step on it indicates a secondary ignition problem but if you used good plugs and coils, that should have fixed it. Have you checked the fuel trims?
My 2002 5.4 has to have dead miss for a code to be thrown.

 

08 truck, DriveWire coils I believe. Plugs were E3.

truck finally popped a code on my way home from work so I’m gunna see what that leads to

 

5.4 engine? Old style or new style plugs?

Get rid of those E3's and DriveWire coils, put Motorcraft parts in.

 

Yes, 5.4 Triton. forgive my ignorance, but I’m not sure between old style vs new plugs…

I’ll work on getting the different parts.

however, last night I was looking under the hood noticed one coil was not fully seated. I installed it properly. Truck seemed to be running fine.

Today, since I’m just paranoid, I Let truck idle and feathered some gas. If I slowly bring the truck up to about 1k rpm and let off i get a “rattle” sounds and then the truck will want to stall. I quickly can accelerate past it (2K rpm )and it will then idle normally.

 

Old style plugs have the smooth ground barrel, new style is fully threaded.

Old style:



New style:



Old style requires high temperature antiseiza on the ground barrel. Both types require dielectric grease in the coil boots.

 

they are new style.

 

You are fortunate. They don't stick and break like the old ones. It was a change in the middle of the 2008 model year.

Plugs are Motorcraft SP509, coils are Motorcraft DG521. You get what you pay for, coils are $40 each.