Vauxhall Workshop Service and Repair Manuals

Compression (4-cylinder), Not Synchronised  

This test must be used for all vehicles with DIS ignition systems, as the system does not permit the measured value to be allocated to a particular cylinder.  

Measurement:	Recording of the battery voltage variations during the start procedure.
Check Objective:	Determining the compression efficiency of the individual cylinder by measuring the difference in voltage between the compression and decompression processes.

Preparation  

Engine oil temperature 20 - 80 ° C (20 - 45 ° C for engines with compression ratio > 10:1). Switch off the engine and ignition. Remove the fuse for the fuel pump or remove the fuel pump relay. Then start the engine and wait until the fuel supply is used up (engine stalls).

Connections  

INPUT A	COM/TRIGGER
Connect the red measurement lead together with the blue filter adapter to the battery. Ensure correct polarity!

Procedure  

Operate starter until "HOLD" appears in the top right corner of the screen. The engine must not start during the test.  

Reference Curve     Notice:  If the message, "The signal was too short for an analysis." appears, the blue filter adapter must be removed and the test must be repeated.

 

Fault Diagram 1   Symptoms:   The value of the cylinder with the lowest compression efficiency is too low. The nominal value is at least 75%.   The next cylinder value has the highest compression efficiency.

Possible Causes	Countermeasures
Leaks at the valves or the piston rings	Perform pressure loss test!

Notice: 

This compression test cannot give information regarding which cylinder is affected. This is only possible for vehicles with ROD ignition systems.