Exhaust pulsation (ignition triggered) during cranking

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

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: When attaching or removing secondary ignition pickups from damaged HT leads there is a danger of electric shock. To eliminate this possibility, switch off the ignition before attaching or removing the secondary igntion pickup.

Note;

You must disable the fuel system before carrying out this test.

  1. Insert the First Look Sensor into the vehicle exhaust tailpipe and connect to PicoScope channel A.
  2. Ensure the ignition is off and connect a secondary ignition pick up around the HT lead for cylinder number 1. Ensure the secondary pick up has a good earth.
  3. Connect the secondary ignition pick up lead to PicoScope channel B.
  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. Crank the engine for 3 to 5 seconds.
  7. With your live waveforms on screen stop the scope.
  8. Use the Waveform Buffer and Zoom tools to examine your waveform.

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.

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.

GT129-2

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

  • WPS500X Pressure Transducer

    £749.00

  • FirstLook Engine Diagnostic Sensor

    £449.00

  • Secondary ignition pickup (capacitive with BNC)

    £58.00

  • WPS500X Pressure Transducer Kit (with carry case)

    £1,055.00

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Guided test: Exhaust pulsation (ignition triggered) during cranking