THIS PRELIMINARY INFORMATION COMMUNICATION PROVIDES INFORMATION TO THE TECHNICIAN ABOUT VEHICLES THAT MAY HAVE AN ENGINE THAT RUNS ROUGH, SHAKE AGGRESSIVELY, SMOKE FROM THE EXHAUST AND/OR KNOCK AT STARTUP. TECHNICIAN WILL RUN THE VEHICLE AND MONITOR FOR MISFIRES, ROUGH RUNNING, EXCESSIVE EXHAUST SMOKE, OR KNOCK NOISE. REMOVE ALL SPARK PLUGS AND REPLACE ANY SHOWING SIGNS OF FUEL FOULING. TECHNICIAN WILL RUN THE VEHICLE TILL OPERATING TEMPERATURE. THEN THE VEHICLE WILL NEED TO COLD SOAK, AFTER THAT RECHECK FOR MISFIRES, ROUGH RUNNING, AND EXCESSIVE EXHAUST SMOKE AND/OR KNOCK NOISE. IF EXCESSIVE SMOKE FROM THE EXHAUST PERSISTS, RECORD THE RESULTS OF THE FUEL SYSTEM DIAGNOSIS IN SERVICE INFORMATION ALSO CONTACT GENERAL MOTORS TECHNICAL ASSISTANCE CENTER. IF THE MISFIRE, ROUGH RUNNING, OR KNOCK NOISE PERSISTS THEN PERFORM STRATEGY-BASED DIAGNOSTICS ON THE SYMPTOM.
