First of all check the battery condition before inspection. If battery condition is not good, communication between ECM and scantool is impossible because of voltage drop. Therefore data would be abnormal.
This test is not absolute result in the engine compression pressure inspection but would be used reference. Because ECM calculates the velocity of revolution in each cylinder at compression stroke by using CKPS signal.
If there is engine hesitation in the vehicle, this test should be performed. Also this test is performed primarily before "Idle speed comparison test" and "Injection quantity comparison test" in the "Engine test function" on the GDS(scantool).
IG KEY "ON", ENGINE "ON".
Allow the engine to warm up to normal operating temperature. (above 80℃)
IG KEY "OFF", ENGINE "OFF".
Connect scantool to Data Link Connector (DLC).
Select "Engine test function" on the GDS(scantool).
Information of ECM version and function available or not is displayed as blow. Press "ENTER" key.
Select "Compression test" on the GDS(scantool).
☞ If test is available, wait for few seconds after IG key "OFF". (Main relay must be "OFF".)
Crank the engine after setting the test condition as below screen. If stop massage is displayed, Stop cranking.
Cylinder engine speed (rpm) is displayed.
☞ The RPM variation of cylinders ＜ 10 rpm
☞ RPM data of abnormal cylinder is the highest.
Symptom | Inspection procedure | |
Case1 | ● RPM data is low at certain cylinder, | ● "Compression pressure inspection by using compression pressure gauge" |
Case2 | ● There is no rpm variation of cylinders, | ● Go to "Injection quantity comparison test" |
Case2 | ● RPM data of all cylinders is low and cranking engine speed is above 350 rpm. | ● Inspect "Timing chain alignment" |
