P0300 Chevrolet -

Question

I sometimes get a P0300 OBD II code ONLY WHEN IT RAINS and I stop at a red light and the engine starts to idle. Then it starts to misfire and idle very rough and almost stall. Then the P0300 code sets. A year ago, during a heavy rain, it happened and I had the plug wires and plugs replaced. Now its happening again. Any ideas?

Answer 1

P0300 Random misfire

For this condition to have a misfire only during heavy rain ,or when it rains use TSB # 00-06-04-024 what this TSB is about is titled " Engine misfire , water in fuel DTC P0300 (Replace EVAP canister vent hose Asm / Replace EVAP cansiter if necessary.) what happens is the engine exhibits a misfire . which is more prevalent in areas with high amounts of rainfall. where water enters through the evaporative emission (EVAP) cansiter vent solenoid  and causes a misfire to occur. Here is the new parts your are to use.