Battery disconnecting - reset ECU?

To do compression test remove plugs and use compression gauge, crank engine over same number of times to get accurate reading. You don't need to disconnect battery, just remove coil wire and ground it to engine. If no distributor and separate coils disconnect coil plug ins. If you get a check engine light after then disconnect neg. terminal to clear. You wont loose any computer settings in ECU. Remember to replace with platinum spark plugs they are much more expensive but go 100,000k Stay away from geek. Always seek a pro tech.