Ford EcoBoost Misfire Coils & Spark Plugs

By the Radman Auto Repair team, independent auto repair in Etobicoke since 1999 · Updated November 2026

Turbocharged EcoBoost engines are hard on spark plugs and ignition coils. Under boost, a worn plug or a cracked coil boot lets the spark escape, so the engine shudders on acceleration, flashes the check engine light and sets misfire codes.

Symptoms

What Causes It

Before You Start

• Park on level ground, set the parking brake and chock the wheels. Never work under a car held up only by a jack: use rated jack stands.
• Let the engine and exhaust cool before you touch them; coolant systems are under pressure when hot.
• Wear safety glasses and gloves, and disconnect the 12V battery before unplugging electrical parts or working near airbags.
• Check for open recalls on your VIN (Transport Canada or the manufacturer’s site) before you buy parts: a recall repair is free at the dealer.
• Remove spark plugs only from a cold engine: aluminium heads strip easily when hot.

Step-by-Step: Ford EcoBoost Misfire

1. Scan the codes. Read the codes and freeze-frame data. Note which cylinders misfire and under what load.
2. Swap a coil. Move the coil from the misfiring cylinder to another one, clear the codes and drive. If the misfire follows the coil, replace it.
3. Clean around the plugs. Blow out the plug wells with compressed air so dirt can’t fall into the cylinders.
4. Remove the plugs. Remove the coils, then the plugs. Look for wear, oil, carbon or a white, overheated tip.
5. Check the new plugs. Use the exact Motorcraft plug for your engine and check the gap against the spec before installing.
6. Install and torque. Thread each plug in by hand and tighten to the torque in the service manual.
7. Refit the coils. Put a light film of dielectric grease in each boot, refit the coils and connectors.
8. Clear and road test. Clear the codes and drive under load. The shudder and misfire codes should be gone.

When to Stop and Bring It In

• The check engine light keeps flashing: stop driving hard to protect the catalytic converter.
• The misfire stays on one cylinder after new plugs and coil: test compression and the injector.
• There is coolant in a cylinder or white smoke: this is a different, serious problem on some EcoBoost engines.
• You suspect carbon buildup on the intake valves: that needs an intake cleaning service.

Not sure, or out of time? Radman Auto Repair in Etobicoke does this repair every week. Book online or call (416) 742-4521.

Also Known As

Owners describe this as “EcoBoost misfire under acceleration”, “Escape shudder when accelerating”, “F-150 EcoBoost misfire”, “Explorer P0300” or “Ford coil pack failure”. Ford calls the coils “coil-on-plug” ignition coils.

Frequently Asked Questions

See also Ford Repair & Service, Spark Plug Replacement, P0300 Misfire Diagnosis, Flashing Check Engine Light.

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