Autolite XP5144 Spark Plug

Autolite XP5144 Iridium Spark Plug

Autolite XP5144 is an iridium spark plug built for performance-focused ignition service. It uses a fine-wire iridium center electrode, a platinum ground electrode, and a tapered ground wire design to support efficient combustion, strong ignitability, and consistent engine response.

Compatible With select Ford F-150, Ranger, Freestar, Focus, E-150, E-250, Escort, Thunderbird, and Mercury Tracer applications, this Autolite Iridium Spark Plug is engineered for direct-fit replacement in a wide range of Ford and Mazda vehicles.

Key Features

• Iridium-enhanced fine-wire center electrode for durability and stable spark delivery
• Platinum ground electrode with tapered cut design for improved electrode life
• Pre-gapped at 0.054 in. / 1.4 mm for many listed applications
• Resistor-type plug with 4,000 ohms resistance
• Copper core center electrode and ceramic insulator construction
• M14 x 1.25 thread size, 5/8 in. hex, tapered seat
• Performance-grade ignition component for secondary ignition service

Product Details

The Autolite Iridium Spark Plug line is built around a fine-wire iridium center electrode and a proprietary platinum ground electrode to improve durability and maintain a consistent spark under demanding operating conditions. On applications such as the Ford F-150, Ford Ranger, Ford Focus, and Mercury Tracer, the XP5144 supports efficient ignition performance, fuel economy, acceleration, and throttle response by helping the engine fire more consistently.

Part number XP5144 is a direct replacement option for a broad range of Ford and Mazda vehicles, including several F-150, Ranger, Freestar, E-Series, Escort, Thunderbird, and B4000 fitments. This part cross-references AGSF34FM and HR8JII33V for the same application.

Common Issues It Can Help Address

• Hard starting caused by worn spark plug electrodes
• Rough idle from inconsistent spark output
• Misfire symptoms related to aged ignition components
• Reduced throttle response from degraded plug performance
• Loss of fuel efficiency due to inefficient combustion

Installation Notes and Tips

Verify engine application, thread size, seat type, and gap specification before installation. XP5144 is pre-gapped, but final fitment should always be checked against the vehicle’s service information, especially on Ford F-150, Ranger, and Focus applications where multiple plug specifications appear across model years. Use proper spark plug socket tools and torque to the manufacturer’s specification to avoid thread or insulator damage.

Quality Assurance

Autolite designs the XP series with an iridium center electrode and platinum ground electrode to support long-term ignition performance and durability in secondary ignition service.