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Old 07-25-2010, 07:33 PM   #1 (permalink)
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chevy 6.0L question.... P0300 code

2004 chevy 2500HD with the 6.0L gasser, auto trans, 4wd, 85,000 miles..... the check engine flashes at RPM's above 2500..... throws code P0300 only when flashing..... doesn't store it. the code says "random multiple misfire" which means it's not cylinder specific which rules out the coils..... (truck has a coil for each cylinder) i have done a bunch of research about these trucks having intake manifold gasket problems..... i replaced that..... still does it... it has new plugs and wires also....

my main question is would a worn camshaft or weak/wore-out valvesprings (which i hear these motors are bad for also) cause misfire problems?? has anybody had this problem before?

tonight i noticed the light flashes when coasting too..... (neither accelerating or decelerating..... )

thanks.
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Old 07-26-2010, 04:42 AM   #2 (permalink)
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The MIL flashing indicates a catalyst destroying event. In other words the misfire is ruining your cats.
It may be worth the hundred bucks to have a GM tech correctly diag it for you.
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Old 07-26-2010, 07:59 AM   #3 (permalink)
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Originally Posted by Odin K30 View Post
The MIL flashing indicates a catalyst destroying event. In other words the misfire is ruining your cats.
It may be worth the hundred bucks to have a GM tech correctly diag it for you.
i know..... as long as i cruise at speeds that keep the motor below 2500 RPM's (73 MPH and below) it doesn't flash at all..... i've read a lot that this was a relatively common problem on these engines..... and also that GM never came up with a fix..... just trying to see if anybody on here has run into this.....
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Old 07-26-2010, 01:37 PM   #4 (permalink)
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What plugs are you using and what are they gapped at?
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Old 07-26-2010, 04:24 PM   #5 (permalink)
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What plugs are you using and what are they gapped at?
AC Delco plugs.... gapped at .040 if i remember right.
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