Objective:
Determining the compression efficiency of the individual cylinder by measuring the difference in voltage between the compression and decompression process.
Measurement:
Recording of the battery voltage variations during the start procedure.
Preparation:
Switch off engine. Switch off ignition. Prepare engine not to start (e.g. remove the fuse to the engine control unit or remove engine main relay). Engine oil temperature 20-80°C .
Note. For some engines it is possible to prevent the engine from starting by performing an actuator test with the Tech 2.
Connections:
| INPUT A | COM/TRIGGER | INPUT B |
|---|---|---|
| Connect the red measurement lead together with the blue filter adapter to the positive terminal of the battery. Connect the ground lead to the negative terminal of the battery. |
Procedure Tech 31:
- 1. Download the Reference curve
- 2. Operate starter until HOLD appears in the top right corner of the screen (the engine must not start during the test; if it does the test must be repeated).
Reference Curve:
Procedure Tech 32:
This measurement is not possible using the Tech 32. The Tech 31 has a preprogrammed function to perform this measurement, which is not available in the Tech 32.