Hi all, im still trying to figure out why one of my fuel trims pegs the max 25% at random times. For reference, I have attached a log where I had gotten to the end of a drive, and saw on my data logger that my bank 1 fuel trim was sitting steadily at 25%, where the AFR was sitting around 13.5. I started logging, let the car sit for about 30 seconds, killed the engine, then restarted the car. All while keeping the same log recording. Upon restart, fuel trims act normally again, and AFR sits at a comfortable 14.7. I hilighted the section where the car was OFF in red, so you can easily see where that happens on the excel file. Can anyone give me some insight onto what could be causing this? I know when dealing with this, vacuum leaks are likely. However I question the vacuum leak due to the problem simply disappearing upon restart.

 

Your bank2 cam advance doesn't change. It demanded duty cycle but the cam didn't change advance, this might be part of the issue. Bank1 appears to be working properly. Might be due to logging the wrong sensor though because I don't see your exhaust cam duty cycle or actual cam sensor readings.

Your battery voltage is also dropping SUBSTANTIALLY while cranking, this likely isn't your current problem because it looks good running on the alternator but you may be due for a new battery soon (or it might just need to be charged).

Bank1 definitely looks like it has more air making it's way into the combustion chamber compared to what the MAF is reading.

Out of curiousity do you hear any kind of "thumping" sound inside the cabin near the glove box when the engine is running. A failing fuel damper might be contributing to this problem.

Logging with all those same parameters plus with upstream O2 sensor data would help. With the data you posted we can see what the computer demands (duty cycle), what the actual result is (trim) , however it all starts with the input from the upstream O2 sensors (bank1 sensor1, and bank2 sensor1) which is missing.

 

As for the trim flattening out on a reset, I think it's time to pull your intake apart, fuel flow test all 6 injectors. Typically you would see inconsistencies on the plugs but you might have a sticking injector on bank1 that's making the entire bank look lean on the O2. Fuel flow testing is quick, easy, and usually cheap (around $100 unless you get a buddy discount).

Or you can just buy an inexpensive Autool C160 for under $300 and do it yourself. That way you can backflow them if needed, sell the tool locally through Craigslist or FB marketplace when you're done with it if you don't want to keep.

Definitely pull the O2 sensor data first though.

 

Thanks for the response. I think the PID is bad for bank 2 cam because the value never moves at all, and I get no errors relating to the sensor. Yesterday I pulled apart the upper intake manifold, swapped all coil packs across banks, as well as injectors across banks. I inspected spark plugs , sprayed for vac leaks, checked test pipes where they mate to manifold and Y pipe, unplugged battery for bourse for reset, and nothing has changed. I also get the ocassional slow response code for both banks on the upstreams, and i’m starting womder if maybe the aftermarket sensors I installed are not operating properly, even though they had 5 star reviews and were pretty expensive. As far as thumping, sometimes i hear this little noise like someone banged a drum pretty lightly, almost like a very deep “THOOP”. But i just assume this is a slight misfire due to the conditions it’s operating under right now. here’s the link to my sensors:

Autopart T ST-54037 New Oxygen O2 Sensor, Upstream, for 2007-2010 Infiniti G35 QX56, 2007-2012 Nissan Altima Armada Cube Frontier Maxima Pathfinder Rogue Sentra Titan Versa Xterra Equator https://a.co/d/1MMkVcU

 

I have to figure out how to pull the specific o2 data. By this, do you mean AFR reading per bank, or voltages? I have access to wide range voltage, wide range equivalence ratio, and I have to check what else.

Yesterday I pulled apart intake manifold, ignition system, and fuel injectors/rail. I swapped the coils and injectors across banks, inspected spark plugs,battery disconnect/ecu reset, and put it all back together. Nothing changed. I’m wondering if maybe the aftermarket o2s i put in when the problem began is the issue, because i get the ocassional slow response code on both banks as well as range/performance codes.

Sensors:Autopart T ST-54037 New Oxygen O2 Sensor, Upstream, for 2007-2010 Infiniti G35 QX56, 2007-2012 Nissan Altima Armada Cube Frontier Maxima Pathfinder Rogue Sentra Titan Versa Xterra Equator https://a.co/d/1MMkVcU

 

I think the HR engine uses two of the same O2 sensor, try swapping those to see if the problem changes to the other bank.

 

I have two new Oem sensors coming tomorrow