when you do a compression test , do you pull one plug at a time and the put it back in or can you leave the plug out and go to the next cylinder ,cause i left each plug out and went to the next cyl. and of course the motor turns over faster so i got a higher reading than the first time example pulled number one all other plugs still in 135lbs went through all other cylinders left all 8 plugs out and tested number 1 again 160lbs should i do one cylinder at a time one plug at a time?