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I've got a 2010 Pontiac G6 with the 2.4 flex fuel. I've got a p0300 code that's been plaguing me recently and thought it could be an interesting one to get some feedback on. Problem began at about 2 in the morning pulling out of my girlfriends driveway after dropping her off (car was up to temp, no other issues)... Misfires on what felt like multiple cylinders. Happened for about 10 seconds and went away. I plugged in my handy dandy $25 bluetooth glorified code reader and found that cylinders 3 had 95 misfire counts and cylinder 4 had 93. A few days later driving down the road at about 45 it happened again for about 10 seconds and gone. My girlfriend started it up leaving her job a few days after that and it did it as soon as she turned it on. When I got there I started it again and sure enough it lasted for about 10 seconds and gone again. This was when it finally threw the P0300. Sorry for the backstory, here's the interesting part.
I had it in the driveway doing some basic checks and trying to get it to duplicate again and after it ran for a few minutes it happened. I had a fuel pressure gauge hooked up and while it was running normally it was sitting at about 60psi. When it began to misfire I noticed the needle jumping form 50-60 psi. Is fuel pressure the route I should be pursuing or would you guys say that's "normal"? I have had an issue in the past with the computer getting the wrong ethanol reading, and have had to reset it in the past multiple times. When that was happening I was getting rich codes. Compression is good (all at about 150 psi). It has individual coils for each cylinder but I don't currently have access to the wiring diagram for the coils. Any ideas are appreciated!
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