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As our cars age, they will start to need more maintenance and we will need to learn more about how to troubleshoot and repair them.

With that said, I would like to introduce:
Motorvate's DIY Garage Ep.36: How to Check Fuel Pressure.
All you need is a $65 fuel tap and a cheap (mine was $9!) 100 psi pressure gauge.
I hope it will be helpful, either now or later

 

Hey so I've been having problems with my bank 2 running super lean at certain times while driving the car, do you know of any way to check the fuel pressure while the car is driving down the road? I don't have access to a dyno (if that even provides resistance to the wheels to simulate real driving conditions) and I can't drive with my hood open blocking my vision, I'm only having this problem while driving and not while stationary or revving in park

 

Low fuel pressure won't cause a lean condition on only 1 bank... it would be on both banks.
You should focus on items unique to bank 2, like A/F sensor, O2 sensor, and fuel injectors.

 

For reference, I have a brand new set of 650cc injectors from AdminTuning, Aeromotive 340LPH fuel pump, Z1 ported upper and lower intake manifold, Z1 3" dual intakes, Z1 catback and ISR HFCs, GTR spark plugs and Z1 coil packs tied together with Z1/Ecutek tune. These have all been installed within the last 2 years. I'm actually going to a local certified Z1 retailer/installer on Monday to check it out and see what's wrong (the guy said maybe the spark plugs cuz OEM is fine until FI) but I sent data logs over to Z1 and they told me bank 2 was going very lean so the mechanic on Monday will just check for me. Thank you for the recommendations though

 

with the bigger injectors I'd suspect the fuel pump isn't pushing the volume to keep up with them (leading the 2nd back to go lean). Although your fuel pump should be fine if working and installed correctly.

 

Yeah I feel like there's an issue with my fuel pump because at idle-2k rpms I don't have the full power that I should be getting, at exactly 2k rpms when going slightly uphill my car kind of bucks back and forth a little bit as if it's trying to burn fuel that it's not receiving, but once I get past 2k rpms it starts acting normally as it should be. I feel like it's some kind of defect in the fuel pump (I've watched tons of videos on how to install it, plus had a mechanic friend take a second look at it and my car in general) and he told me the fuel pump could just have a defect in it, but we'll wait and see what the other Z1 certified mechanic says on Monday

 

My 2¢
I assume you are planning for FI / E85, as 650cc injectors on a NA VHR is way too big.

For example:
At a hot idle, the VHR injector pulse width is about 0.002 seconds (2 ms)

Assuming stock fuel pressure of 3.5 Bar / 51-52 psi, the 650cc injectors are almost 1.7 times larger.
With the 650cc injectors, the injector pulse width is now about 0.002 / 1.7 = 0.00118 seconds or 1.18ms
That may not be enough time for the injector to fully open and explain why at low load/low RPM the engine is lean.

Now why only on bank 2? Maybe 1-2 fuel injectors are no able to fully deliver the required fuel due to the low pulse width.

-OR- I could be way off and it could be something else

 

So I'm planning to run 93 but still have E85 as an option if I want to, that's why I did everything instead of just keeping the HFCs when my oem ones went bad. I went with 650cc because I talked back and forth with Z1 and that's what they recommended me on my car as well as what's been proven on other customer cars (plus AdminTuning makes an E85 kit which includes their 650cc injectors). I installed a Z1 fuel port and Deatschwerks fuel pressure gauge a few weeks ago and noticed today when my dad and I were filling up my coolant was that my fuel pressure was running at 63-65 psi at idle which is quite a bit over factory rating, and when I first installed the fuel pressure gauge it was bouncing around between 50-65 psi really fast. The injectors are all brand new from AdminTuning which I got back in November. I called Aeromotive yesterday and they were telling me that I would probably need to check the fuel line filter, get an aftermarket regulator, and even install a fuel return system (I believe they said 3/8" lines back and forth) while Z1 told me that none of that would be needed to run what I wanted to do. At this point I'm just tired of thinking about it and spending money on stuff that "maybe might fix the problem but not with certainty" and I'm just getting it checked out Monday

 

Update: the Z1 mechanic I went to today said the GTR spark plugs really do not help unless I'm forced induction, otherwise they burn too hot and don't make a good spark. That would make a lot of sense as to why I'm seeing reduced power and fuel economy, gonna swap to OEM Denso plugs and see what happens. He also sent a picture of how the GTR ones look if anybody knows spark plugs and wants to give their two cents about them

 

So what are the updates? Was it spark plugs or not??

 

Not gonna lie, completely forgot about this thread lmaoooooo. So basically my local Infiniti dealer never told me they didn't change my transmission fluid during their "change all fluids" promo so I was at 115k miles on original transmission fluid, and basically my torque converter **** itself apart with TC metal ending up in the trans pan (not good). The torque converter was acting funny at those rpms, and I tried changing my trans fluid which did help for a couple weeks, until one day when my car kept trying to stall out in 1st gear at low rpms (shut itself off when I was parking at the barber). I get home after the cut, and when I got home and it died out on me again, it kept stalling out every time I put it in reverse or drive in my driveway so I'm lucky I got home. So essentially I needed a whole trans rebuild so I brought it to a trans shop and he completely rebuilt it (new clutch packs, new heavy duty VTP Trans torque converter, brand new Nissan/Infiniti valve body/TCU unit, new fluids, etc plus external trans cooler) for $6400 with a 1 year warranty (plus a Z1 flex plate for $600). I was looking into a VR30 swap but the only company that warranties them is Soho Motorsports, and we don't have enough for $10k for everything to be warrantied ($2k for valve body/TCM, $1800 for a VR30 trans instead of letting me buy one for $600 and inspect it to make sure it's good to warranty, $1600 for transport from NJ to NC, etc). It's been a few weeks with my car back (ofc my thermostat got stuck closed a week later so it overheated until he fixed it also) and I feel like a few days after I got it back, it's having similar issues again with the torque converter which makes no sense. Sometimes my third gear goes up by 200 rpm when I shift up when cruising, sometimes when I shift down I get a big jolt, I just think this car is a POS and now I want to get rid of it. I also only get like 12-13 mpg so I have to start being conscious with that also, and we're a lower middle class family so we don't have enough money/income to keep dumping money into this car as much as I want to keep it. I also have oil catch can kits installed a month or so ago, so whoever gets this car after me (after replacing oil gallery gaskets also) will have a nicely modded G37 that will last until at least 250k miles albeit with worse fuel economy than a stock one.

One other thing I haven't tried yet, Z1 (my tuner) said they changed some things in my tuning to hopefully make my car stop bucking and acting weird as much, so I have to hit them up and ask them if their tuning for that could be a reason why my car feels weird still. Either way, I think my ownership of the G is coming to an end soon after a big car show end of September, so I just hope it ends up in good hands instead of some muppet who unplugs the 10-amp AWD fuse everywhere and goes to takeovers and ****

 

So the bank running lean and the spark plugs were just a red herring?

 

Pretty much yeah, although I needed to change the spark plugs anyways because GTR ones aren't good for NA G37s