sonicii

I would be starting with this wire, when this is grounded, it engages the relay that supplies power main to the ECU and a few other items. I suspect this relay should NOT be energised when the ignition is turned off. Either the ECU is faulty and is grounding this pin on the ECU full time, or there is a short to ground somewhere between the ECU connector and this relay. Pull the relay and use a multimeter on ohms between pin 36 (I think it is 36) of the IPDM and ground, you will likely measure near enough to zero ohms. Unplug the ECU and check again between 36 and ground, if it is now open, it is likely the ECU at fault, or something telling the ECU the ignition is still on, if you are still measuring something similar to the first measurement to ground, you probably have a wiring problem. If you can unplug the IPDM, do that, if you still measure low resistance to ground at that relay connector, the issue is in the IPDM, if you are now measuring high or infinite resistance, the issue is in the harness.

at $45k, might be why they are still for sale. Redbook range is $25-33k for a 2018 RS. There is also a 2019 400R for $62k and a 2020 for $56k on carsales. So I would expect a 2023+ to be more. Personally, I don't think the JDM version looks much better, tails do. but front? meh.., so for that sort of $ difference, I would take a late AuDM Q50 and put a bit aside for new turbos when they go, but everyone has their preferences..

you can pick up a 2018 AuDM RS for around $30k, can you really get a 2023 JDM V37 for that? If so I may need to consider one...

when you pulled the ECCS connector, do you still have 12V at pin 31 of the IPDM, if you do, this suggests a problem with the relay (which you probably eliminated by swapping relays), or a wiring problem between IPDM pin 36 and ECCS pin 31. ( I hope those pin numbers are correct, they are a little hard to read). As Duncan mentioned if you have a short to ground on that wire, it will keep that relay engaged all the time.

As above, I would be looking into why they relay is engaged when the ignition is NOT on. If there was supposed to be full time power on this circuit, why have a relay there? 400mA may be perfectly normal when that relay is engaged and not indicate a faulty item supplied by that relay.

What does the JDM V37 400R offer over the AuDM V37 Q50 RS? Other than a newer build?

yeah, that's not a VQ hybrid engine, it isn't even a VQ35HR.. that is a VQ35DD, which is a bit of a unicorn, only fitted to a couple of vehicles, but definitely not the hybrid. It is a direct injected engine for a start, the HR isn't.

hmm.. maybe you just need to go up to a 6pk1190 or even a 6pk1200

something isn't right there, the last one I bought was a 6pk1170, which is 10mm shorter and it fitted fine. are you sure everything is stock?

problems like that under heavy load is often spark related, either plugs or coil packs. As above, the lack of a CEL doesn't always mean all is healthy on the ignition front.

I would agree with Duncan, although I have the Q50 Hybrid, the drivetrain is pretty much identical. I haven't had any issues at all with mine, it is a 2015 model and I have owned it for just over 3 years now. My local Nissan dealer won't touch it, I asked them if they can do a DAS wheel alignment (not sure if DAS was on the Fuga), and they just refused, saying they don't know anything about working on Infinitis, so no way would they be interested in touching the hybrid system. If you happen to live somewhere near one of the ex-infiniti dealers/workshops, they will probably more willing to help. @Duncan what battery is $5k? maybe the Fuga pack is different, but for the Q50, the complete battery pack is about $12k from Japan, or an individual cell module is around $1,200. Although once the car is a few years, Nissan recommend replacing the entire battery pack if you have a module fail.

If you have an AuDM Infiniti G37, my first suggestion would be one of the ex-infiniti dealers, like Brighton. however, if you have an imported V36 Skyline, then I am not sure, dealers can be a bit finicky about imports.

Yeah, tongue weight or 'downforce' is usually 10% of the towbar's rating. So a bar rated to tow 1500kg will often have a downforce rating of 150KG. To get a weight of around 225kg (I'm not old enough to speak in lbs), you will likely need a 4WD or similar vehicle, I have never seen any towbars on regular sedans with a figure that high, maybe it was an option on the old Falcons and Commodores? What fuel economy are you seeing? my old V35 6MT returned around 11L/100km in the city and around 7.5L/100 on the highway, which I thought was pretty good for a large 6cyl with a performance focus.

They have had a few unexpected issues with the VR30DDTT in USA, turbo failures, at least on some of the earlier models, with some suggestion they have fixed this with updated turbos fitted to the newer models. Also reports of porous blocks, which is a bit concerning. I am not sure if, or how common these issues are on AuDM or JDM examples. I am kind of happy I picked the Hybrid, performance is only slightly down on the RS and there are no tuning options, but fortunately that works fine for me. The newer RS models did get some nice suspension options though! Hybrid was never an option on the Q60 though!

Intercooler coolant uses electric pumps, they might have a 2nd pump on the RS. I didn't think they had 2 separate systems on the RS, maybe just a higher coolant flow and larger heat exchanger on the front.