I have a 06 f150 5.4 with about 175xxx on it.
My power steering went out so I took it to a mechanic. I never used him before but he came recommend, same shop for 30 years, 5* on Google etc.

I had him fix my p.s. leak, and wanted new plugs and coils packs,, as well as a oil change. I wanted to do some preventative maintenance because this is my work truck.

When I went to get it a few hours later the mechanic mentioned something about a misfire. I didnt think nothing of it till I went to leave and it was misfiring bad and the check engine light flashed and I've never saw that before.
Now my truck had no known misfire when I brought it in. Nor has the cel ever flashed for a misfire.

The mechanic said he checked all the new plugs and coils but its still misfiring.

He didn't have the compression test adapter for the motor and had to order it off his tool guy and it should be in today.


Is it possible to have a misfire so slight its hardly noticeable?
Im not dumb and I know vehicle, let alone my work truck so i know it wasn't misfiring before the plugs and coils got changed..

Is it possible that the new plugs and coils caused another weak system to go and thats causing the misfire?

 

What brand coils were used?

 

No idea what brand coils ill ask when im there tmrw

 

Also find out what brand plugs.

 

Your mechanic needs to test each coil individually without any codes present. Personally, I'd pull the plugs and test those too.