Triggered engine idle test

The purpose of this test is to look at exhaust pulsations with the First Look sensor to assess engine condition whilst running.

How to perform the test

Connect the First Look Sensor to Channel A on the PicoScope using the 25 ft BNC to BNC cable as shown in Figure 1, then attach the sensor to the exhaust pipe as shown in Figure 2.

Now connect the Secondary Ignition pick-up Lead to Channel B of the scope and attach the clamp to the cylinder 1 plug lead. Start the engine and allow to warm up. With the engine idling adjust the timebase and voltage scales to achieve best signal display.

This test is useful in assessing overall engine condition taking into account the fuel delivery system.

Example waveform

Waveform notes

This waveform shows a consistent signal pattern on Channel A as triggered against Channel B on the same time line. Cursor lines are added to show trigger reference (sparkplug 1) and show the time between trigger events. We can use this information to determine the approximate cranking speed of this engine.


This help topic is subject to changes without notification. The information within is carefully checked and considered to be correct. This information is an example of our investigations and findings and is not a definitive procedure. Pico Technology accepts no responsibility for inaccuracies. Each vehicle may be different and require unique test settings.

Suitable accessories

  • Flexible Back-pinning Probe


  • Secondary ignition pickup (capacitive with BNC)


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Guided test: Exhaust vs Ignition (Idling)