Problem: Vehicle was brought in because the MIL
(Malfunction Indicator Light) was on and the engine had a slight
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.