I have a 2019 F-150 XLT 3.5 liter ecoboost with a misfire issue. I have 103000 miles on it and recently replaced all the spark plugs and coil packs. I had this issue about a month ago in the number 4 cylinder. I replaced the coil pack and spark plug again and it seemed to have fixed the issue till recently. It only happens when the engine is under load 10 PSI or greater boost. Had anybody else had this issue and if so what was the cause and fix.

thanks!

 

Welcome.

 

I don’t know 3.5 specifically, but you can generally isolate/confirm issue before throwing money/parts at it: just move/swap parts from problem cylinder to other cyl, clear codes and then test drive. If misfire moves with swap, you’ve zero’s in on problem. For my gen, probability seems to be ‘coil boot/spring’, plug, and then plug or actual coil. OEM coils rarely fail.

If I were in your position, I’d move/swap current/existing 4 parts: coil to 1, plug to #2, injector to #3 (take notes on what you do), clear codes, then test drive and rescan.