Failure mode - Ford Triton gasoline (Super Duty / Excursion / E-Series)

Spark plug ejection / stripped plug threads (2V heads)

Reliability tier: verified - verify before ordering, see /disclosure/

Symptoms

a spark plug blows out of the head under load ('shot out like a bullet')
misfire with a ticking/chuffing noise at one cylinder; plug wire pops off
plug threads stripped in the aluminum head after a plug change

Root cause

The 2V heads have only ~4 threads engaging the plug (the plug seats above the gasket surface in a shallow counterbore) and share a coolant passage area; combined with over-torqued or corroded plugs, the plug can blow out under cylinder pressure or the threads strip at removal. Ford publishes its own thread-repair procedure (TSB 07212, 'SPARK PLUG THREAD REPAIR PROCEDURE', 4.6L 2V/5.4L 2V/6.8L 2V, MY2002-2005 doc) - OEM acknowledgment that the repair is a defined service path, not a machine-job-only event.

Diagnosis

confirm which cylinder and whether the plug or the threads failed
borescope / thread inspection of the seat; check the plug for stripped threads vs sheared shell
if ejected: inspect the coil boot and the seat for debris before the repair

Fixes

chase and insert-repair the seat with a thread-repair kit (Time-Sert / Calvan class) and install a fresh correct plug (thread insert repair) - no head removal; the insert restores full thread engagement; maker instructions govern (D-013)

Spark Plug Thread Repair Kit, 2V heads (Time-Sert / Calvan 38900-class)

install a fresh plug with correct torque if the threads are intact (early catch) (plug-only) - cheapest path; only valid if the threads held

Spark Plugs, 2V heads (Motorcraft SP-479 / Ford AGSF-22W-MX)

preventive: correct-torque plug service on the interval instead of running plugs to failure (prevention) - cheap; the single biggest ejection reducer is not over-torquing corrosion-hardened plugs

Spark Plugs, 2V heads (Motorcraft SP-479 / Ford AGSF-22W-MX)

Prevalence

very-common