GTSBoy

If you google for R34 manual you will find a working link to download it.

Do you have the wiring diagram? If not, get it.

Of course it's at the switch that you touch with your fingers.

Those cams be f**ked.

Take multimeter and wiring diagram to car. Start poking around where there shouldn't be power when the switch is off.

It's still hydraulic. The pump is electric. Just the mechanical power to run the pump goes via the alternator instead of the PS pump belt.

Quoting this just to make sure it doesn't go away.

Put steering wheel back on. Put nut back on 1.5 turns. Beat the crap out of the back side of the wheel.

Won't be CAS. Unlikely to be coilpacks. More likely to be injectors. Rich from problem injectors is nowhere near as common as lean from (dirty) injectors, but it does happen. Are you all sure it's fuel and not oil?

Wiring diagram and a multimeter.

Wires are switched somewhere.

Clutch <> compressor. Compressor could be fine. Probably is. The compressor and clutch are going to be common with other cars. Take it to an auto electrician, particularly one who also does air-con regassing etc. And how can it be hard to find someone is San Fransisco to rebuild a compressor? I live in a backward city in a backward country where we all hang upside down from the ground, with a population of only a million or so people and I can probably come up with a list of 5 or 6 places that I would be able to get an air con compressor done. You have SF (pop 1M, LA (pop ~4M), the rest of California (~40M), every other city on the west coast, every city everywhere else in a country with 300 million people.

Of course it is. A 1" diameter increase on the wheel is a normal and trivial thing to do. No it won't. The aim when you put bigger wheels on is to choose a tyre width and (lower) profile to keep the rolling diameter of the new wheel/tyre combo to within a few % of the existing rolling diameter. If you have a known speedo error now (say, you can tell it reads 4km/h fast at 100 km/h, checked by GPS speedo or something equally trustworthy) then you can often choose your new tyre sizing to get rid of some or all of that existing error. Not that you would make this your first priority, but it is an available input to your choices.

It's not a pity at all. HICAS is a liability and interferes with vehicle stabiilty at the limit. It was only created to make the car feel more willing to turn in when driving at <7/10ths. Try to drive the car properly hard and HICAS fights the driver's inputs. Better neutralised than kept. 30 years later, the computers running 4WS systems are better. Back then, they sucked. Too simplistic.

What type of coils are dying? OEM? Good aftermarket (ie Splitfires)? Dubious aftermarket (ie, yellow/red/rainbow)?

I would suggest that that wheel would be no more legal than what you're using now. Sure, it will have an airbag.....but it is effectively a one off handmade thing that has no type testing at all. That is the very antithesis of ADR requirements and wouldn't stand up to 3s of scrutiny at a true roadworthy check (such as at the actual DMV, not some mechanic's roadworthy). I think you're just going to be spending money for money spending's sake here, rather than actually achieving anything useful.

I can connect to and talk to my HICAS CU with a diagnostics handset, but I cannot see the wheels turn, because all the HICAS hardware has been removed from my car and thrown in the bin, like it should be on all R chassis cars.

I have never heard of an aftermarket windscreen moulding for any car that wasn't an old chrome bumper classic for which there was a market for restoration parts that are NLA from the OEM. I am a fluid dynamics engineer, and I would advise you to not worry about it. There are so many other things to worry about first!

^ all-brand, not all-rand.

Who owns one? Not me. My friendly neighbourhood workshop does. Helps that it's my brother-in-law's workshop. But, any decent general automotive workshop needs to have an all-rand capable scan tool to do anything with modern cars. If a workshop doesn't have one, they just can't fix vehicle electronic problems these days.

Yeah - good luck. I've only ever managed to interrogate mine with a workshop grade scan tool. Like Snap-on, or similar.

What device are you trying to do this with?

True.

300rwkW RB20 is laaaaaaaaaaaaag followed by 2000rpm of power.

And besides which, who searches forums using the built in forum search engine? They are usually so f**ked up that they simply don't find what you want or have restrictive settings about not using words of less than 2 characters, etc etc. The only smart way to search any forum is to deliberately search it from Google. You can tell Google to only search a specific site, and awaaaaay you go. Been doing that since Google became useful more than 15 years ago.