P0300: Intermittent Misfire
10-08-2014, 08:39 PM
#33
Double check your pushrods length first. I had a very similar issue, it ended up being a sticking lifter. Occasionally the intake valve was held slightly open and lt was allowing the combustion to come back into the intake and cause a p0300. Had very strange symptoms, the way I found it was run it with the valve cover and when it was missing at idle, loosen each rocker arm until it begins to tap until you find one that clears up the misfire. Mine also seemed to start after reaching operating temp.
10-10-2014, 07:43 PM
#34
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The second shop unplugged one of the o2 sensors today and truck ran fine. Plugged back in and misfire came back. O2's sensors are new so not sure how they'll be able to fix that.
10-14-2014, 06:58 PM
#36
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I've still got what seems to be a closed loop misfire. Everything I have found on the internet indicates replacing the 02 sensors resolved the issue for people with the same problem. I have replaced the old sensors which I knew to be operational, with new o2 sensors and the problem persists. Any thoughts?
10-14-2014, 09:17 PM
#37
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Had the same issue just a couple weeks ago when I installed the my cam (228r). De-sensitized the knock sensors with hp tuners and it went away. I think the factory setting was 32,767 and I changed them all to 32,000. The ecm is actually mistaking the "chop" of the cam for a mis-fire. I would wager it is in the tune. Don't just delete the dtc, as you do still want to know if something happens.
10-14-2014, 09:20 PM
#38
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99% of people will get this code after a cam swap. I would get it to a tuner and have him do his thing. I went through the exact same crap and come to find out, I was chasing a mechanical issue that didn't exist. Quit pulling your hair and get that thing tuned dude!
