NGK 91164 Spark Plug

NGK Iridium IX Spark Plug for Ford Applications

NGK Iridium IX Spark Plug 91164 is built for performance-focused ignition service with a fine-wire iridium center electrode, tapered cut ground electrode, and resistor design for stable spark delivery. It is a direct-fit option for select Ford EcoSport, Fusion, Escape, Focus, and Fiesta models with the specified 0.028 in. gap.

Key Features

• Iridium fine-wire center electrode for durable spark performance
• Taper cut ground electrode for improved starting, idle quality, and throttle response
• J-gap ground configuration with a tapered seat design
• Resistor spark plug with 5,000 ohm resistance
• Copper core center electrode and nickel ground electrode core
• Pre-gapped at 0.028 in. for the listed Ford applications
• 14 mm hex, M12 x 1.25 thread size, 25.0 mm reach

Product Details

The NGK Iridium IX line is aimed at drivers who want consistent ignition performance in modern engines. Part number 91164 uses an iridium center electrode with a high melting point and fine-wire design to promote strong ignitability, while the tapered cut ground electrode helps support cleaner starts, smoother idling, and sharper throttle response. This spark plug is listed for 2014-2020 Ford Fusion, 2017-2019 Ford Escape, 2015-2018 Ford Focus, 2014-2017 Ford Fiesta, and 2018-2021 Ford EcoSport, making it a relevant choice for Ford owners servicing factory-style ignition systems. This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.

Common Issues This Part Can Help Address

• Hard starting or delayed ignition response
• Rough idle caused by worn spark plugs
• Reduced throttle response during acceleration
• Misfire concerns related to plug wear or fouling
• Loss of fuel efficiency from degraded ignition performance

Installation Notes and Tips

Verify the engine application and plug gap before installation. The listed fitment uses a 0.028 in. gap, tapered seat, and M12 x 1.25 thread size, so confirm the cylinder head specification matches before service. Use proper spark plug removal and installation procedures to avoid thread damage, and torque to the vehicle manufacturer’s specification. For Ford Fusion, Escape, Focus, Fiesta, and EcoSport service, confirm the ignition system is in good condition before installing new plugs.

Quality Assurance

NGK is a recognized ignition component manufacturer, and the Iridium IX design uses iridium metallurgy and a resistor construction suited to modern engine demands. Part number 91164 is engineered for consistent spark performance and durability in the listed Ford applications.