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Autool  |  SKU: SPT301

Autool SPT301 | Spark Plug Tester

5,0 1 review
€45,95 incl.
€37,98 excl.

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The Autool SPT301 spark plug tester is designed for visual inspection and performance analysis of components within the ignition system. This diagnostic tool enables technicians to assess the quality, stability, and color of the spark under simulated engine load. The tester is primarily used for targeted diagnosis of ignition problems in 12V petrol engines, where misfires, weak sparks, or internal breakdown can be quickly identified without keeping the components mounted in the vehicle.

During the diagnostic process, the tester generates the required high voltage itself and takes over the function of the ignition coil, allowing the spark plug to be mounted directly in the test station. The spark quality can be assessed by continuously simulating engine speed between 200 and 9000 revolutions per minute, with the set RPM remaining visible on the display. The device is equipped with height-adjustable threaded connections to support various plug shaft lengths. A closed safety cap over the test setup is required to activate the circuit, ensuring safe visual inspection of the spark without risk of contact with high voltage.

KEY FEATURES

✔Three test ports — One reference port and two test ports, allowing suspect spark plugs to be compared alongside a known good plug.
✔Wide simulation range with adjustable RPM frequency up to 9000 revolutions per minute.
✔Operates only with cap closed — The high voltage circuit activates only when the protective cap is closed, preventing contact with high voltage.
✔Digital RPM display — The display shows the set engine speed, making tests repeatable under exactly the same conditions.

LIMITATIONS

✕Not suitable for measuring the internal resistance value of the spark plug.
✕Requires component removal; in-vehicle diagnosis is not possible.
✕Dependent on mains power via the included power adapter.
✕Spark plugs only; glow plugs from diesel engines cannot be tested with this device.

Application and Functionality

The Autool SPT301 offers specialized testing functions for evaluating spark plugs outside the combustion chamber.

  • RPM simulation: Generating high-frequency operating voltage to simulate engine speeds from 200 to 9000 revolutions per minute, allowing visual assessment of spark plug behavior under varying loads and high speeds.
  • Comparative spark analysis: Simultaneous operation of three test ports. One port is designated for a new reference spark plug, while the other two ports are used for the plugs being tested, enabling direct observation of performance differences.
  • Visual spark diagnosis: Assessment of spark color, intensity and stability to identify flashover, internal insulation defects, abnormal spark paths or severe electrode wear.

Special Features and Capabilities

This model is equipped with hardware modifications to enhance compatibility and ensure safety during testing.

  • Height-adjustable test ports: The threaded connections can be mechanically adjusted up to 8 millimeters in height. This allows proper grounding connection for spark plugs with an extended shaft or non-standard threaded position.
  • Integrated high-voltage protection: The device features a transparent safety cover. The high-voltage circuit is protected so the test cycle can only be started when the cover is fully closed.
  • Digital control panel: An illuminated display shows the currently set RPM. Using the push buttons, you can incrementally increase or decrease the test frequency for precise control.

Compatible Vehicles and Ignition Systems

The tester is designed for universal use with components from standard 12V ignition systems.

  • Vehicle category: Passenger cars, light commercial vehicles, motorcycles and other gasoline-powered combustion engines.
  • Ignition system: Conventional and electronic 12V ignition systems with individual spark plugs, including extended-shaft versions.
  • Diagnostic application: Testing spark quality and physical flashover of removed spark plugs on the workbench.

Package Contents

  • 1x Autool SPT301 spark plug tester
  • 1x Power adapter 110V or 220V to 12V DC
  • 1x User manual
💡
Good to know: Perform visual spark plug tests in a darkened environment. Weak leakage currents along the ceramic insulator and spark color variations are much easier to detect this way. Also run through the complete RPM range: a spark plug that produces a clean spark at 700 revolutions per minute may still misfire at 9000, and that difference is exactly what explains a misfire that only occurs under load.

Technical Specifications

Specifications Description
Product Brand Autool
Product Model SPT301
Product Type Stationary spark plug tester for benchtop use
Number of Test Ports 3, including 1 reference port and 2 test ports
Simulated Engine Speed 200 to 9000 RPM, adjustable
Display Digital display with RPM indicator
Test Height Adjustment 0 to 8 mm
Compatible With Spark plugs for 12V petrol engines
Adapter Input Voltage 110V or 220V AC, with 10 percent tolerance
Device Operating Voltage 12V DC, 1A
Safety Feature Test cycle starts only with safety cover closed
Operating Temperature 0°C to 45°C
Relative Humidity Less than 85 percent
Dimensions, L x W x H 200 x 118 x 118 mm
Weight 500 grams
Item Number SPT301

Reviews

5,0 ★★★★★ 1 review
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★★★★★ Albert H.

Great device

Tested spark plugs that had only done 10,000 km which according to the garage were the cause of a misfire compared to a new one. Spark plugs are perfectly the same spark as new spark plug at 700rpm and even at 9000rpm. Tip test them in a dark room, you see the difference better.