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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??
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
Did you gap the plugs @ .035 or below?
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?
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?
You would have to be waaaaay rich for too cold plugs to cause a misfire under load.
maybe injectors?
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?
it did that when my catylic converter started clogging up. and i had them removed and it solved the problem.
you also may have a burnt valve, that causes compression issues. that may also be your problem.
The trick turbo kit I have does away with the catylic converters so I doubt that has anything to do with it.Quote:
Originally Posted by donald wildes
I thought about this theory for awhile but after doing some research and talking with a few mechanics.. I found that a burnt valve would be almost a dead skip on the given cylinders; however, my truck was jumping around all the cylinders and at any given time there was usually only three cylinders misfiring.Quote:
Originally Posted by donald wildes
Edit: For some reason the check engine light went back off yesterday by itself and hasn't came back on since.. maybe it will stay off this time.