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p300: started back..running rough and no power..highway..200 miles…

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I drove my car to...
I drove my car to a store started back up 1 hour later and it was running rough and no power. I limped it to the highway and it started to run like it should and drove 200 miles with no problems. I pluged my scaner to car and it says P0300. I looked code up and said misfire. What should I look for?
Submitted: 8 years ago.Category: Chevy
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Answered in 8 minutes by:
6/12/2010
Chevy Mechanic: John, ASE Master Technician replied 8 years ago
John
John, ASE Master Technician
Category: Chevy
Satisfied Customers: 637
Experience: ASE Certified Master Technician, ASE Certified Service Consultant, 22 years professional experience
Verified
Hello

The P0300 is a random misfire code. Which means one or more cylinders have a misfire but the engine computer cannot determine yet which cylinders are misfiring. I would start by looking at spark plugs and spark plug wires. Look for worn or cracked plugs and wires with burn spots on them. If you replace all that and the code returns then a vacuum leak could cause this or even failing fuel injectors. Start with checking out the plugs & wires. You can do a visual check of the vacuum lines and listen for a vacuum leak with the engine idling. The fuel injectors can be checked with an ohm meter. They should all have the same resistance (or within .1 or .2 ohms of each other). Unplug them before checking them.

Let me know how this works out for you.

John
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