2015 CHEVROLET SUBURBAN 5.3L - P0300 RANDOM MISFIRE
Engine run rough, check engine light on, service code p0300. Well Which cylinder is misfiring? How can you pinpoint which cylinder? Let start with something simple and go into live data on the scan tool and watch misfire count. Another way to find out which cylinder is to do a balance test. Disconnect each ignition coil connector and the one that show no change is the way a engine run is normally the one that is misfiring. On this vehicle we did a compression test, all cylinder is sitting at roughly 135psi. Found #5 cylinder with excessive misfire count. Pulled spark plug and it was dry even with ignition coil unplug. Verify that there was injector pulse from the connector. Replace injector and misfire went away.