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Old 10-07-2014, 11:58 PM   #1
HalfTon
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Join Date: Jul 2011
Location: Imperial, MO
Posts: 128
p0300 random missfire puzzle

Well I bought what seemed to be one of my dream trucks. 1999 chevy reg cab short bed, 4x4, 5 speed, and with a 4.8. I knew the truck had some issues but nothing serious. 300 miles after buying it the SES came one with p0300. eventually the light began to flash but I never noticed a lack in power. My scanner is just a basic one so it will only give me freeze frame data, so i cannot determine which cylinders are supposedly missfiring. I started with the basics and replaced:
plugs and wires
checked fuel pressure regulator
changed fuel filter
fuel presssure is in spec
no vacum leaks found
cleaned maf, throttle body, and k&n air filter
all coil packs are producing spark
Where should I go from here?? the truck idles and starts fantastic and I have never actually felt the engine missfire. If I clear the code, sometimes it will stay of for 50-60 miles and other times it will come back within 7mi.
What do you guys think I should try next?
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69' custom/10 longbed.

1999 1500 4x4 5 speed
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