'13 GX 460 - Help troubleshooting misfire
 

I have a 2013 GX 460 with about 65,000 miles. Yesterday morning when my wife went to garage and started up vehicle, it immediately began misfiring. She shut it off and got me. I started it and there was no indication of a misfire but the check engine light was activated and the "no trac" lamp was on. I checked codes and the only code present was P0308 cylinder 6 misfire. I cleared code and she drove vehicle around rest of day without issue. This morning, same thing. She went to garage, started up vehicle and it was misfiring again. After starting and shutting down the vehicle twice, the misfire disappeared but the engine and no trac lights were light up again. I checked codes and it said P0308 cylinder 8 misfire. I cleared codes and she want off about her day with the vehicle running fine. Originally, I thought I may have a coil going bad on #6 but now I'm not sure what is going on since its read a misfire in both # 6 & 8 cylinders. This seems to be isolated to just cold starts (my garage is about 50 deg). Any suggestions or help will be greatly appreciated. Thanks in advance.

First thing I would do is replace the spark plugs on at least 6 & 8 or all if it has never been replaced. Also check for oil in the spark plug well to make sure the seals are good. It has been reported by other members that the seals tend to give up before the spark plugs are due and oil seeps into the wells.
If that does not help I would start replacing the coil packs and wires on 6 then on 8.

^^ The oil seal does seem suspicious with 6 and 8 being beside each other. 65,000 miles with the warranty, time for a trip to the dealer. Please keep us posted.

https://www.clublexus.com/forums/gx-...-with-oil.html

Thanks for the suggestions. I pulled spark plug on #8 and no oil was evident. The plug looked to be in great shape. Bought a new coil and installed it in #8. The car sat for several hours and was cold when I started it and got a misfire and check engine light but it quickly went away after I shutdown and started right back up again. The check engine lights went out as well. I checked code and got P0308 cylinder 8 misfire. Did a test ride and it runs perfect. Could it be an injector? Not even sure where those are located or how to remove. How about bad fuel or dirt in injector? Any other suggestions?

Yes, it absolutely can be the fuel injector too... maybe just dirty since it happens only when cold.