Exhaust pulsation (ignition triggered) during idling

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

Connection guidance

Connection for diagnostic work will vary dependent on application.

Technicians should whenever possible gain access to the test circuit without damage to seals and insulation. If this is not possible then make sure appropriate repairs are completed.

General connection advice

PicoScope offers a range of options within the test kits.

Dependent on difficulty of access, choose from:

  1. Breakout leads.
  2. Back-pinning probes.

Testing sensors and actuators (to include relevant circuit/connectors):

  • When testing a sensor, it is desirable to gain access at the control module.
  • When testing an actuator, it is desirable to gain access at the actuator.

How to perform the test

   

WARNING

Uninsulated HT pickups are designed to clip around double-insulated HT cables only – they are not designed for direct connection to a hazardous live voltage. To prevent injury or death, switch off the engine and secure against restart. Clean and inspect the HT lead for damage to insulation and fit only to undamaged fully insulated leads. Ensure that leads are safely clear of hot and / or rotating parts. The engine can now be restarted for the test duration.

  1. Insert the First Look Sensor into the vehicle exhaust tailpipe and connect to PicoScope channel A.
  2. With the ignition off, connect a secondary ignition pick up around the HT lead for cylinder number 1 and to PicoScope channel B. Ensure the secondary pick up has a good earth.
  3. Start and run the engine at idle.
  4. Minimise the help page and with the example waveform on your screen PicoScope has already selected suitable scales for you to capture a waveform.
  5. Start the scope to see live data.
  6. With your live waveforms on screen stop the scope.
  7. Stop the engine and ensure the ignition is off.
  8. Use the Waveform Buffer, Zoom and Measuring tools to examine your 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.

Waveform Library

Go to the drop-down menu bar at the lower left corner of the Waveform Library window and select, Exhaust / tailpipe pressure waveform.

GT130-3

Disclaimer
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

  • Secondary ignition pickup (capacitive with BNC)

    £58.00

  • FirstLook Engine Diagnostic Sensor

    £449.00

  • Dual WPS500X Maxi Kit (with carry case)

    £2,285.00

  • HT Extension Lead

    £41.00

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Guided test: Exhaust pulsation (ignition triggered) during idling