Failure mode - Ford 3.5L EcoBoost Gasoline (F-150, Expedition, Transit, Raptor - 2011-present)

Ignition misfires: spark plugs and COP coils

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

Symptoms

MIL with misfire DTCs P0300-P0306
rough idle and flashing MIL under load
hard start after misfire events
lack of power on the high-output tune (2019 Limited TSB case)

Compare with the other causes of the same sign on this engine: hard start, long crank or no-start (5 causes) · loss of power, limp mode or derate (5 causes) · misfire, rough idle, hesitation or surging (5 causes)

Root cause

Turbo GDI engines stress plugs and COP coils harder than NA engines; plugs live a shorter interval, and coil boots/housings fail under boost. Ford issued a MY2011-2013 misfire-DTC diagnostic bulletin and a 2019 high-output misfire/lack-of-power bulletin.

Diagnosis

read misfire DTCs and freeze frames; identify the cylinder pattern
swap-test the coil on the misfiring cylinder; inspect the plug for gap/erosion
check for CAC-condensation events (multi-cylinder, humid-weather single event) before condemning ignition parts
on Gen1, verify the plug service interval was kept - gap erosion reads as random misfire under boost

Fixes

full set of plugs (turbo service interval, not the NA interval) plus the failed coil(s); boot/inspect on every cylinder ()

spark-plug - more than one option: 3.5L EcoBoost Spark Plug, Gen1 (current number CYFS-12-YT4X), 3.5L EcoBoost Spark Plug, Gen2 (current number CYFS-12Y-PCTX), 3.5L EcoBoost Spark Plug, Gen3 (DYFS-12Y-PT)
ignition-coil - more than one option: 3.5L EcoBoost Ignition Coil, Gen1 (BL3Z-12029-C), 3.5L EcoBoost Ignition Coil, Gen2 (current number HL3Z-12029-D), 3.5L EcoBoost Ignition Coil, Gen3 (ML3Z-12029-C)

Prevalence

very-common