P0300- Multi Miss Fire..... Help!
02-18-2010, 08:01 PM
#12
Mine is throwing the code. I have changed the wires and plugs and nothing as of yet but I went to try to go threw inspection and I failed do to the system not ready to be scanned.... Complete BS! But if that solved the problem I will post back up and let you know for sure. 
02-18-2010, 08:04 PM
#13
Staging Lane
Join Date: Oct 2009
Location: Severna Park MD
Posts: 62
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i had that problem trying to go through emissions in a van i just tuned up to pass. pissed me off. they just do that so you cant clear it right before you go there. heck last time i took my truck they never even plugged it in they put the sniffer in the tail pipe.
02-19-2010, 05:58 PM
#20
RJ, you have tuning software? you can pass emissions if you create a tune that turns off all the codes that are being tested. Just put the tune back to normal once you pass so you can work out your issues.
How do you know it's all the cylinders? p0300 is "random". p0301 is cylinder 1, p0302 and so on. Not that the cylinder specific codes are a catch all. The problem isn't there during load because airflow is substantial enough to correct the mathematical issues. That usually means the MAF is oiled down, post maf leak is huge, or you have a small spark leak (in the wires,coils, crack plugs) that is only noticeable at idle. But I gotta tell ya, I watched my plug wires arc across the headers and I didn't catch any misfires. (I even put my misfire settings to stock)
Post MAF leak will drive your fuel trims nuts but usually doesn't lead to misfires. Because the MAF is calculating the airflow (or helping) and the o2's are telling the pcm it's too much air. So the o2's just keeping telling the pcm to correct the trims. Think of the trims as fuel handicap.
I have the opposite problem...misses at full load.
How do you know it's all the cylinders? p0300 is "random". p0301 is cylinder 1, p0302 and so on. Not that the cylinder specific codes are a catch all. The problem isn't there during load because airflow is substantial enough to correct the mathematical issues. That usually means the MAF is oiled down, post maf leak is huge, or you have a small spark leak (in the wires,coils, crack plugs) that is only noticeable at idle. But I gotta tell ya, I watched my plug wires arc across the headers and I didn't catch any misfires. (I even put my misfire settings to stock)
Post MAF leak will drive your fuel trims nuts but usually doesn't lead to misfires. Because the MAF is calculating the airflow (or helping) and the o2's are telling the pcm it's too much air. So the o2's just keeping telling the pcm to correct the trims. Think of the trims as fuel handicap.
I have the opposite problem...misses at full load.