iTester – Relative Compression

This test is only a comparison between cylinders so we can use this method to “see” if we have a cylinder (s) with low compression by comparing one cylinder to the next. Hence the term “relative”.

Relative compression is the fastest, simplest way to find a low compression cylinder. This test has previously been available only on large and expensive diagnostic systems, requiring a laptop and an oscilloscope. Now it is easier than ever — with the new CarScope i-Tester that combines both functions – relative compression test and automatic waveform analysis.

So, the final results are displayed in an easy to understand format.

You do not have to check each individual cylinder, all cylinders can be tested in one go. CarScope i-Tester works on 3, 4, 5, 6, 8, 10, 12-cylinder cars, 4 stroke, diesel and gasoline engines, DIS, conventional and Coil-on-Plug systems, and 12V electrical systems.

By hooking up a second probe to either the ignition or an injector, you can follow the firing order/injection sequence and know which one it is. This is not the only way to do this type of cylinder identification but it does work as a way to start with.