Engine compression test

This page covers general engine compression test as implemented in BimCOM and in future also other tools.

No special tools are required to perform the test, no engine component disassembly is needed. This is pure OBD-II diagnostics test.

Test prerequisites:

  • Engine OFF
  • Ignition ON
  • Transmission must be in neutral

Test procedure:

  • Immediately after starting the test, start engine for at least 5 seconds (engine won't start)
  • On some systems engine starter is automatically started when test is run (depends on specific model)
  • After stopping starting, do not turn ignition "OFF" (leave it ON, otherwise connection with diagnostic tester may interrupt)
  • Some systems may automatically stop starter after some time

The test may either run automatically (e.g. no data are displayed during test procedure, only result is shown) or manually (continuous measurement while engine is starting)

Visual data interpretation

(this chapter applies to all cylinder based tests)

Numerically: Individual cylinder values are displayed (current value, minimum and maximum reached during the test for each individual cylinder).

Graphically using bar meter: all bars are scaled equally and have same minimum and maximum value. Green area represents individual cylinder minimum-maximum range (equals to numerical value). Black line show average value for all cylinders, red line shows current cylinder value.

Coverage in SECONS diagnostic tools