Denso 3140 Spark Plug

Denso 3140 Spark Plug for Toyota Supra

The Denso 3140 is a conventional spark plug built for stable ignition performance in select Toyota applications. Its U-groove ground electrode design helps improve ignitability, supporting more consistent combustion and engine efficiency in the right application.

Compatible with 1987-1992 Toyota Supra, this Denso U-Groove Conventional spark plug is built around a copper core center electrode, nickel tip materials, and a standard ground configuration for dependable secondary ignition service. The 5000-ohm resistor helps control electrical noise, while the 0.8 pre-gap supports OE-style replacement needs.

Key Features

• Denso part number 3140 for select Toyota Supra applications
• U-groove ground electrode design for improved ignitability
• Copper core center electrode for efficient spark transfer
• Nickel center and ground electrode tip materials
• 5000-ohm resistor for reduced electrical interference
• Flat seat, 14.00 mm thread diameter, and 19.00 mm reach
• 16.0 mm hex size with 20 heat range specification

U-Groove Conventional Product Line

Denso’s U-Groove Conventional line focuses on a ground electrode shape that exposes the spark path more effectively than a standard flat design. In this application, that layout supports cleaner ignition events and consistent engine operation for drivers maintaining a factory-style spark plug setup on the Toyota Supra.

Detailed Description

This Denso spark plug is engineered for 1987-1992 Toyota Supra models and is identified by part number 3140. The U-groove ground electrode, copper core center electrode, and nickel electrode materials work together to deliver reliable spark delivery in a conventional plug format. The flat seat and OE-style dimensions make it a direct-match service part for the listed fitment.

This part cross-references DENSO Auto Parts (e.g., Q20R-U) for the same application.

Common Issues This Part Can Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle from weak or inconsistent ignition
• Misfire conditions related to degraded plug electrodes
• Reduced fuel efficiency from incomplete combustion
• Loss of throttle response from aging secondary ignition components

Installation Notes and Tips

Verify the specified thread diameter, reach, seat type, and pre-gap before installation. Use the correct torque procedure for the cylinder head material and confirm the ignition system is in good condition so the new plug can perform as intended. For fitment, this Denso 3140 spark plug fits 1987-1992 Toyota Supra, N/A.

Quality Assurance

Denso is known for OE-level ignition component engineering, and this spark plug follows the dimensional and material specifications listed for the application. Confirm vehicle year and engine details against the fitment data before ordering.