I have a 2005 Chevy trailblazer Lt. It has 130,000 miles on it. about once every other week or more the engine light will come on. I had Onstar do a diagnostics check and they came up with a code of P0300. They said it was the emission control system and that the engine has a misfire. Today i took it into Walmarts garage and they came up with the same code of P0300 but said it was random multicylinder misfire. When the engine light comes on it will only stay on for the most 2 days that we have seen in the 6 months we have had it. I am a Marine veteran with little cash so i would appreciate any advice to the least expensive way to solve this problem. Thank you for your time and any replies!

 

I had a misfire on my 2006 Trailblazer. I had about 60,000 miles on the spark plugs, so I decided to change them. I found about an inch of water in the #1 spark plug well. I don't know where it came from - it was water, not coolant. I sopped the water out of the well so it wouldn't fall into the cylinder, changed the spark plugs and it ran fine after that.