Compression testing
Posted: Fri Jan 15, 2010 11:19 am
I am looking at the workshop manual at the section regarding compression pressure check. It all looks pretty straight forward but I do have one question.
Keeping in mind that for this test you need to remove all of the spark plugs and disconnect the crank angle sensor, the manual states 'crank the engine with the throttle valve fully open'.
(I can just picture me holding the removed throttle body in my lap in the cabin, holding it open with one hand and turning the key with the other and looking puzzled. If I was better at drawing I would include a picture.)
This has me a little confused. Do I need to re install the intake manifold after removing the spark plugs? Is this just so the air entering the engine is filtered? If so, what about the spark plug holes?
If disconnect the crank angle sensor stops the ECU from carrying out ignition and fuel injection, the only thing I am achieving by cranking the engine is turning the starter motor. I just can not see any good reason for the intake manifold having to be reinstalled or opening the throttle valve if the intake manifold is not installed.
Keeping in mind that for this test you need to remove all of the spark plugs and disconnect the crank angle sensor, the manual states 'crank the engine with the throttle valve fully open'.
(I can just picture me holding the removed throttle body in my lap in the cabin, holding it open with one hand and turning the key with the other and looking puzzled. If I was better at drawing I would include a picture.)
This has me a little confused. Do I need to re install the intake manifold after removing the spark plugs? Is this just so the air entering the engine is filtered? If so, what about the spark plug holes?
If disconnect the crank angle sensor stops the ECU from carrying out ignition and fuel injection, the only thing I am achieving by cranking the engine is turning the starter motor. I just can not see any good reason for the intake manifold having to be reinstalled or opening the throttle valve if the intake manifold is not installed.