This Preliminary Information communication provides information to the technician about vehicles that may have misfires or rough running on cold start up. Technician may find a Diagnostic Trouble Code P0300. Technician will need to use a scan tool and observe Crankshaft Position Re-sync Counter parameter. The Re-sync Counter parameter should remain at 0 during all operating conditions, and while manipulating the related harnesses and connectors between the crankshaft position sensor and the Engine Control Module. Technician will need to inspect for water intrusion in related connectors, terminals, and components. Tech will need to bring the vehicle up to engine coolant temperature that was stored when Diagnostic Trouble Code P0300 was set. After the engine coolant temperature is up to temperature technician will need to perform compression and cylinder leakage and record the readings. Technician should also verify correct fuel system pressure, inspect the heated oxygen sensors for contamination from fuel, silicon, or the incorrect use of room temperature vulcanization silicone sealant, and inspect the spark plugs for incorrect heat range, coolant or oil fouling, carbon tracking, cracks or insulator fractures at the tip. Technician should also Test for coolant contamination into the cylinders.
