Autolite 3924 Spark Plug

Autolite 3924 Copper Resistor Spark Plug

Autolite 3924 is a copper resistor spark plug built for quick starts, smooth acceleration, and dependable everyday ignition performance. It is an OE-style replacement for a wide range of foreign and domestic vehicles, including many Audi, Toyota, and Mitsubishi applications.

The Copper Resistor Spark Plug line is focused on practical OE form, fit, and function at a value-oriented price point. Autolite supplies ignition products to the automotive aftermarket and OE manufacturers, and this plug follows that approach with a standard copper center electrode, nickel ground electrode, and ceramic insulator construction.

Key Features

• Autolite part number 3924
• Copper center electrode core material for consistent ignition performance
• Resistor type spark plug with 4,000 ohms resistance
• 0.044 in. pre-gap size for OE-style applications
• Flat seat, 14.0 mm thread diameter, 5/8 in. hex
• Mid-projection ceramic insulator and tapered ground electrode tip design
• OE-style replacement for many Audi A6 Quattro, Toyota Prius, and Mitsubishi Outlander Sport applications

Product Details

Autolite 3924 is engineered as a direct-fit secondary ignition component for vehicles that call for a copper resistor spark plug with a 0.044 in. gap. The standard regular center electrode design, nickel tip materials, and flat seat configuration support OE-style service on a broad range of applications. This part number is commonly searched for by drivers looking for an Audi A6 Quattro spark plug, Toyota Prius spark plug, or Mitsubishi Lancer spark plug replacement.

This part cross-references Champion Spark Plug 71 for the same application.

Common Issues This Plug Helps Address

• Hard starting caused by worn spark plugs
• Rough idle from degraded ignition performance
• Slow throttle response during acceleration
• Reduced fuel economy from inefficient combustion
• Misfire symptoms related to aged secondary ignition components

Installation Notes and Tips

• Verify vehicle-specific fitment before installation, especially on Audi, Toyota, and Mitsubishi applications.
• Check the pre-gap against the vehicle service specification before use.
• Use the correct 5/8 in. hex spark plug socket and torque to the manufacturer’s specification.
• Inspect ignition coils, wires, and boots during spark plug service to confirm the rest of the ignition system is in good condition.

Quality Assurance

Autolite manufactures this spark plug to OE-style form, fit, and function standards for a wide range of makes and models. The brand’s ignition product experience and aftermarket/OE supply background support consistent replacement quality for routine maintenance and tune-up service.