OK so some background:
The Car –
2003 G Coupe 6MT – bought new, last six of VIN is 202172 153500ish miles
Car sat for 5 years, but never really had mechanical problems, has been back on the road for three years.
Had to replace the #2 coil pack when she was resurrected
Consumes oil ~quart/500miles – High mileage Mobile One 10/30
Injen CAI and not much else
P0300 (Random misfires) code under hard acceleration @ about 4500 + RPM
The higher the gear, the more noticeable the misfire I.E. Under heavy load in 5th gear it is worse than 4th gear etc.
This is especially noticeable in humid conditions.

A year or so ago, my route to work included an interchange with a loop that wound around to a larger highway. I usually would come out of that loop at about 75ish-80 in the dry, but when it would rain my car would get pretty squirrely, and I would get sideways on my way around it, so I would let it hang out. If there were standing puddles around the area I would get a jump into limp mode 100% of the time. I finally just took it easier around the loop to reduce the chance of that happening, in the rain. Even taking it easier the car would go in limp mode if I broke traction in 4th + gear in the wet, particularly at highway speed. If my slip mode came on, I was in limp-mode, but only if my foot was in the throttle, and I was in the rain/puddles. Since the Injen has its filter near the bumper intake opening, I figured that I was scooping up some extra water, and throwing MAF reading off, especially since it is a hot-wire type sensor.
I found that it would come out of limp mode while I was working during the day and “something” dried out. Later I figured out that I could disconnect and reconnect the airflow sensor and it would come out of limp mode on restart.
Now it seems to be happening spotty anytime above 4500RPM, regardless of rain, without the limp-mode (no loss of traction/slip lights). It is still more pronounced in high humidity. I have different tires, with much better wet grip, so I have not really been losing traction in the wet like I was.

I do have automotive background as a former Nissan tech, and I previously worked at a Z-Car speed shop outside of Atlanta (in another life, late 90’s). I understand most of the systems involved in this scenario, but want some confirmation that my suspicions of a bad MAF sensor is the probable culprit. The other things that keep going through my mind would be ignition, but since it has individual coils, it would mean that one coil (maybe two) are failing at high duty cycle, and immediately straightening out when the duty cycle drops to normal. Possible that a crack in the coil-pack shielding is allowing an arch to ground at high duty-cycle, but I would expect missing at other RPM ranges, not just a sudden collapse at 4500RPM. For that matter, the same could be happening for the fuel injectors, but I find either unlikely.
It could be a cam or crank position sensor, but I am not getting other strange issues that I would expect from either. Though, I can see that as the cams change to a more advanced timing, the transition may not be registering in the sensor. But, I am not sure that the code supports either case, and I would expect reduced power, rather than an all-out miss condition.
The ECU could have issues, but I would expect the problem to happen at various RPM ranges, rather than a specific range.

Please give me some feedback and help me figure this out without having to spend a million dollars shot-gunning a solution. Thanks.

~Wulf

I checked these posts, but none were conclusive or 100% like my issue:

https://g35driver.com/forums/general...oss-power.html

https://g35driver.com/forums/engine-...e-shaking.html

https://g35driver.com/forums/engine-...-4500-rpm.html

https://g35driver.com/forums/engine-...elerating.html

https://g35driver.com/forums/g35-cou...hat-check.html

 

Well I found some other posts with similar issues after a bit more digging. Cleaned my MAF and it solved about 90% of my issue. Now I cut out at very high RPM randomly on acceleration. I am thinking this may be due to a bad coil pack. Going to try some insulation troubleshooting sometime, maybe next weekend, starting with #6, since it seems to be the biggest problem child.

 

Yeah I was going to suggest corrosion on the heated wire element in the MAF causing part of the problem, I don't know how successful you will be in cleaning it with MAF cleaner though, removing oxidation buildup with a can of aerosol spray isn't very effective.

These vehicles are NOTORIOUS for coil pack failure, yours are near the end of the expected life (1 already replaced), personally if it were my vehicle I would replace them all preventatively rather than waiting for them to go out one at a time over the next few years.

A couple other things of note, you should seriously consider switching back a stock airbox if water ingestion is even a remote possibility

Try switching back to the factory Nissan oil to correct some of the consumption issue, mine ('06 revup) drinks a little less than yours (2qt per 3k miles) if I put mobile1 synthetic high milage into it but drinks almost NOTHING (1/4qt per 3k miles) if I use the stock Nissan oil