Hello friends, I need some help. I have a fairly lengthy story that involves a P0300 code(random cylinder misfire)to tell but I feel more info is better than not.



I bought an ’06 pathfinder 4.0L (VQ40DE) I few months ago knowing it needed some timing chain work. It ran fine with a bunch of chain noise. One evening it was turned off, the next day our temperatures dropped to -30 degrees Celsius(-22F). that afternoon the vehicle wouldn’t start. We assumed it was due to extreme temp drops. We burned out the starter in the process trying to boost and start it. I had it towed to my heated garage where it sat for a couple of days to thaw out and where I could change the starter. Once replaced we tried again. It turned over and sounded like it would fire but nothing. Tried to spray ether into the intake to see if it was a lack of fuel issue, still wouldn’t start. After a lot of discussion, we decided it was time to change the timing chain and as I already had the parts… lets go for it! Stripped it down, replaced all 3 chains ensured we were TDC adjusted the cams as per the service manuals instructions and all the indicators on the sprockets lined up.



While changing the timing chain I did a couple of other things,

-changed spark plugs

-did an engine flush

-changed serpentine belt

-air filter

-changed the intake plenum gaskets(confirmed there is no leak)



Hooked everything back up and she fired up…. But ran like crap – P0300B.it runs enough to mobilize the vehicle with not very much power. Checked all my connections, took out the MAF, cleaned it, put it back(even unplugged it while it was running to see if that would change anything and it did… ran even more like crap while unplugged) I have unplugged the coil packs and some injectors while its running to see if any of those makes a difference and they don’t. while unplugged it still runs the same. I unscrewed the coil pack while running pulled it out to see if it was sparking and it would spark against the sleeve. Took the VVT solenoids off, cleaned and tested – both operating properly. The code doesn’t present itself at first or sometimes not at all but the vehicle always runs like crap.



This job has consumed a whole bunch of my time and I would like to see if there is anything else that could be the issue before I start going into dark thoughts like having to remove the timing chain cover again.



Thank you for staying with me through this long post. Any help is appreciated!