Originally Posted by
Vadim Proper way to do a compression test is with all plugs removed. The reason that I can think of for this is, other plugs being installed will create pressure and slow down the crank for the cylinder you are actually testing.
I have known many mechanics who do it one plug at a time as well. Who knows, we will see. If you guys say it is better with all of the plugs out, then so be it, sound sgood to me!