Strange failure of tappet/lifter and injector at the same time?
2001 with a 4.7, started running rough... then 10 seconds later it was fine. The next day it started idling rough again but didn't recover.
System showed a miss on #3. A new coil was put on since it was handy with no change. Plug was pulled and it was wet. Compression test showed 60 pounds... not enough for combustion...
Valve cover was pulled and rocker was removed on intake valve. Valve sealed with air being pumped in so that lifter/tappet was replaced. Compression now back to 135.
Still running rough. Injector ohms checked and within range of others. Injector tester connected and injector not responding correctly so it was replaced.
Runs like new now.
Coincidence the lifter and injector failed at the same time???