An image showing the PicoDiagnostics software icon

PicoDiagnostics - Compression test

What it does

The Compression test within our PicoDiagnostics software (bundled with PicoScope 7 Automotive) reveals engine mechanical issues by calculating relative compression values for each of your engine’s cylinders. The compression values are displayed as a bar graph for easy comparison.

You can add a WPS500X pressure transducer to give you absolute compressions, in units of bar or PSI, across all cylinders.

How it can help you

As the relative Compression test uses simple, non-invasive, connections, is easy to set up and quick to complete, it is a convenient way to assess your engine’s mechanical health. As such, it saves you time so you can get on with diagnosing other faults and fixing vehicles.

Technicians are rarely able to diagnose engine mechanical faults with a scan tool or without additional tooling and equipment. However, the Compression test comes for free when you buy a PicoScope Automotive oscilloscope so you get all the other benefits associated with our scopes, as well as a dedicated compression tester.

The Compression test algorithms run when you crank the vehicle’s engine. Therefore, engine health is continuously assessed during real-life load conditions, giving you a realistic appraisal of its health.

The Compression test supports almost all engine types so you can use it to test commercial, marine, agricultural and off-highway/heavy-duty engines, as well as those within cars aging from the classic era to the present day. In fact, the Compression test is compatible with almost any alternator equipped engine.

You can save, print and share all your Compression test results. The clear printout is designed to share clear, color-coded (red, amber, and green), diagnostic outcomes with your customers, which promotes trust in your customer relationships.

How to use it

Disable the vehicle’s fuel pump and/or injection system so that it won’t inject fuel into the cylinders and start running during the test.

Connect your PicoScope Automotive oscilloscope to the vehicle with a test lead connected to the battery terminals.

Open PicoDiagnostics, select Compression test, select the number of engine cylinders and press Start.

Once the Compression test has detected a suitable battery voltage it will ask you to crank the engine.

When cranking is detected, the Compression test will capture six seconds of data whilst you continue cranking.

And that’s it.

After that, the Compression test will calculate and display the relative compression for each cylinder as a percentage of the maximum detected. From there, you are free to save, print, share and act on the results as you see fit.

An animation showing how to use the PicoDiagnostics Compression test