Problem: Vehicle was brought in because the MIL (Malfunction Indicator Light) was on and the engine had a slight misfire.
Details: The technician connected a scan tool and found DTC P0303 – Cylinder three misfire. No other DTCs were found. First, he checked the coil and spark plug. Both components tested fine. Next, he checked the injector trigger signal with a scope. It looked normal. After he was satisfied the problem was not fuel or ignition related, he checked the compression pressure pattern in cylinder #3 with the scope.
Confirmed Repair: From the scope pattern (see images), he found that the intake and exhaust valve pressures were not the same. He removed the valve cover and inspected the valve springs and the camshaft. The camshaft lobes were worn out. The camshaft was replaced and the problem was resolved.