My truck is giving me the P0300 code which is Random Cylinder Misfire. I checked all the plug wires, plugs are new, took the metal boots off the plug wires, and even changed the coil packs. It feels rough esp under boost.. and when the RPMs get above 3K or so the check engine light starts flashing at me. What does this mean??
Current Mods: 6.0/4L80e with Trick Performance Front Mount
Audio: Pioneer avic-d3, Memphis Belle, Two 12" Rockford Fosgate P3 shallow mounts, Memphis MS-Qs, and custom vinyl enclousure.
Just because plugs are new doesn't mean anything, check them again and make sure you didn't crack the porcelain putting them in and double check those wires
2006 silverado SS....Clifford Jr...turbo coming soon
1970 Chevelle ly6 swap....d1 coming soon
Did you gap the plugs @ .035 or below?
Gone, but not forgotten!
Alright, I tripple checked my plug wires and also checked the plugs. I even changed the knock sensors cause I knew the ones out of my 5.3 were good. Also went over the grounds to make sure they had good contact. I'm not sure what to do now.. I'm guessing it could be a number of things from a short in an O2 sensor to a mechanical problem?
Last edited by ThunderBolt; 08-13-2009 at 09:58 PM.
Current Mods: 6.0/4L80e with Trick Performance Front Mount
Audio: Pioneer avic-d3, Memphis Belle, Two 12" Rockford Fosgate P3 shallow mounts, Memphis MS-Qs, and custom vinyl enclousure.
Did you just have a different cam installed? Your tuner may have forgotten to disable the random misfire code. That's what happened to me.
Ummmm.....it's not a problem in the tune if he feels the miss. If it's under load it's most likely ignition as mean05 said. The SES flashing means the PCM is picking up a misfire bad enough to harm the cats (even if they are no longer there it does tell us the PCM knows the misfire is fairly severe).
Spark plugs are TR6s gapped @ 35 if that makes any difference. Wondering if it's too cold maybe?
Current Mods: 6.0/4L80e with Trick Performance Front Mount
Audio: Pioneer avic-d3, Memphis Belle, Two 12" Rockford Fosgate P3 shallow mounts, Memphis MS-Qs, and custom vinyl enclousure.
You would have to be waaaaay rich for too cold plugs to cause a misfire under load.
maybe injectors?
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My injectors aren't but six months old and they're 42#s. Is there any way to test them.. can you scan this on HP tuners? I'm wondering if I forgot a ground somewhere cause it seems the battery voltage hasn't been wanting to hold every since I put the 6.0 in.
Also I had to get these heads resurfaced because they were warped.. could the valves be hurt causing a compression issue?
Last edited by ThunderBolt; 08-13-2009 at 11:00 PM.
Current Mods: 6.0/4L80e with Trick Performance Front Mount
Audio: Pioneer avic-d3, Memphis Belle, Two 12" Rockford Fosgate P3 shallow mounts, Memphis MS-Qs, and custom vinyl enclousure.
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