Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › Continuous missfire › Continuous missfire January 6, 2020 at 6:14 am #895678 Richard KirshyParticipant Fuel trims use a scanner. Compression test you can use a basic compression gauge or using a scope, do a relative compression test. Secondary ignition wave form can only be done with a scope.