joshuaho96

That seems different from the one on the R33, which is almost identical to the coolant temp sensor used by the gauge. Basically just a rectangular large flat blade single terminal device.

Intake air regulator is not the same as AAC valve. Intake air regulator is only there to raise the idle airflow at cold start. After a certain amount of engine runtime the shutter should fully close and all idle airflow goes through the AAC valve instead.

Sounds like the easiest way of figuring this out is to somehow find an R34 wiring diagram manual. Unfortunately I don't think I've ever seen one myself.

When looking at that wiring manual it says it is A-17. If you go to the wiring section you can match it up to this ECCS/H connector: I'm having a hard time interpreting your drawing but my best guess is it is the power steering switch. Keep in mind R33 and R34 are not guaranteed to have the exact same harness pinouts.

Sure. Make sure to put some dielectric grease on the terminals and cap it in case future you wants to run electronic boost control again.

There's a lot of things that are weird on the R-chassis wiring/circuit design. Link highlights all the time how parts of the AC control system are always connected to +12V which can cause weird interactions that cause their ECU to brown out and cause no-starts in circumstances that it shouldn't. Nothing obscene, but just a little funny and no longer considered best practice.

I can take some better pictures when I get around to pulling the transmission on my R33 but this will probably give you some idea of where it's routed.

It is for idle up signaling when the power steering is under high load. For example if the car is stopped and you turn the steering wheel all the way to the end of travel. My best guess is the thread is identical but unless you can measure yourself it’s hard to be sure. The R32 switch is generic for Nissan so you might be able to find one in a junkyard or a cheap aftermarket alibaba special just to check fitment. Then buy OEM new for actual road use. I’m unclear on whether the R33/34 need the clearance on the switch hence the special part requirement. I’m pretty sure 4.7V corresponding to open switch is normal. The ECU can detect it too, voltage can exist in the absence of current flow. When the switch closes as the impedance is very low relative to the voltage source it drops to near 0V which can also be sensed.

Engines are expensive. You already mentioned having thermal management issues with your car, anti-lag dramatically raises EGTs and can easily damage a cylinder head. If your goal is actually to improve transient response I recommend VCAM. DBW can also help here. Instead of a simple mapping of accelerator pedal position to throttle opening instead you interpret the accelerator pedal as a certain torque/power request and the throttle will open more or less to achieve that. So if your desired acceleration requires getting 0.5 bar of boost the throttle will silently go wide open to spool the turbos, then as it gets to that target intake manifold pressure it will adjust the throttle back to the steady state target. Another trick you can play is detecting when a shift is happening using a strain gauge and clutch switch for example and rather than snap the throttle shut when the accelerator pedal closes you cut fuel injection and hang the throttle open to keep the turbo from slowing down. This is a pretty complicated trick to play though as if it got stuck in that logic you would have engine runaway and you want to make sure the engine RPMs actually fall at a reasonable rate instead of rev hanging badly.

Interesting, this might solve my "wtf do I do for catback" dilemma.

It's a harness connector. I have no idea why you think it's the AC compressor leaking power steering fluid out of there, it's not physically possible for that to happen. Most likely it's related to the bodged power steering valve/high pressure line. That valve and the threads it's attached to has to hold like 1000-1200 psi. Fix all of that first and foremost.

Looks like 49761-V5400 might fit but you would need to make an adapter harness.

That probably permanently raises the idle. If it seems like the idle is higher than you want try capping both ends. I really doubt the part is discontinued because Nissan used it a million cars from the late 90s and early 2000s.

That is called the power steering valve. It is designed to raise the engine idle when you put excessive load on the power steering pump to keep the engine from stalling. Replacement is 49762-AA000.

Have you checked that the starter signal fuse hasn't popped in the fuse box? This is the simplest thing to start with. Then verify that your ignition switch is providing a low resistance path from pin 5 to pin 1 when the ignition switch is turned to the start position: I misspoke earlier about the starter motor being ground switched. Technically going by the circuit diagram the solenoid is always connected to ground and actually you have to provide +12V to it via the ignition switch to power it. If you have confirmed the switch is working normally then you're down to a wiring fault and you have to chase the signal wire from the harness back into the cabin. Most likely it is the Wiring Specialties harness. I have gotten mis-wired harnesses from them before.

The starter signal from the ignition switch just connects the starter solenoid to ground. There will always be +12V on one side of the starter solenoid.

The F80/G80 are pretty close, just don't bottom out/scrape on anything substantial because all that's protecting the oil cooler from puking 7 quarts out is a crappy piece of plastic they call a skid plate. Not unusual to take off the covers and discover that the whole cooler is bent and needs replacement.

Yes, in the case of the F80 it's basically such that air from the front of the car that would want to bypass the radiator/charge cooler/condenser stack is instead forced down through the oil cooler and then ducted out the bottom. It's definitely annoyingly complicated and not that simple. Power steering also suffers from similar problems, the factory "cooler" is just some fins attached to one of the hardlines running along the subframe and it's not really good enough to keep the fluid from boiling/out of the reservoir under track use.

30/70 should be standard in any tropical climate. If it never drops below 0C this is an easy way of getting more performance out of the cooling system. Nissan explicitly recommends this. If you want to go even more extreme you can go 100% distilled water with redline water wetter. Change it frequently if you do this as I'm doubtful on the corrosion protection. Make sure the airflow into and out of the cooler is managed. Don't use excessively restrictive mesh on the intake or exhaust for the oil cooler. A friend of mine has tested this himself when installing a front mount intercooler on his car. Seal up any gaps in the ducting. You may want to find some way of fitting a larger oil cooler in the space that the HKS cooler currently uses but that core is already pretty close to what is practically possible. You can also try to fit a cooler in the space where the OEM diverter valves live but that's a bit challenging like the HPI kit. Or you can take the F80 M3 approach and put one laying flat under the radiator/intercooler/etc but you need to be extremely careful about not scraping the underside of the car. F80s are notorious for emptying their oil pans when someone takes a speed bump too aggressively or scraping on a curb.

Make sure the radiator fan shroud is on and in good condition. Make sure all the radiator guides are in place. Make sure your intercooler isn't restricting too much airflow to the radiator. Change your coolant out for a 30/70 glycol/water mixture instead of the normal factory recommended 50/50. Make sure your radiator is halfway decent, so not Mishimoto. Make sure your fan clutch is functioning properly. If you have the factory oil/coolant heat exchanger a larger oil cooler or better ducting can help take the load off the cooling system. If your tune pulls out way too much timing to achieve the power figures that it does and the pressure peak is happening well after TDC turn down the boost. Less thermal efficiency means more of that heat is going into your coolant and engine oil instead of the wheels. E85 would likely help a lot in this situation as it naturally has more water dissolved in it and the combustion of alcohol releases a lot more water than gasoline. I would also recommend doing some temperature logging of various fluid temperatures. Rear differential, transmission, transfer case, front differential, power steering fluid. Gear oil shouldn't exceed ~140C. If it is getting too close for comfort you might need to consider some method of cooling it off better. Keep in mind that these systems are kind of all interconnected. The oil pan holds the front diff for example and keeping the engine oil cool will help cool the front diff in turn.

That is pretty much overheating on an RB. Should never exceed middle of the temp gauge. In my experience normal temp it never even gets to the middle reading 80C.

I think I'd settle for just pulling the engine. Then may as well have everything else inspected while you're at it and think about throwing a stroker kit in there with valve relief pistons for 50 degree advance VCAM and maybe a spline drive oil pump and other oil control mods on top of that and maybe a helical front LSD too.

Start with an idle power balance test. Consult cable will let you shut off fuel to one cylinder at a time without having to risk breaking an injector harness clip or have the metal clip go flying off into the abyss.

I have never had to think about this before but that makes sense. Too much boost bleeding off going to the wastegate actuator will overwhelm the atmospheric vent.

Wastegate stuck open will make the exhaust louder because the turbine is being bypassed but it will not make a sucking noise. It will affect idle but not enough to cause issues. Only way for that to be an issue is if the wastegate actuator rod is so loose that exhaust is leaking out from it. Exhaust leaks are usually not that complicated to spot otherwise. Any leak will be magnified by exhaust visibly leaving soot or heat damage to gaskets, external surfaces of cracks, etc. Make sure the BOV is not stuck open. If this is running stock ECU/your tune is not speed density get rid of the atmospheric vent and do 100% recirculation. A boost leak test would show if you had a problem there. You can also try capping the throttle body and only pressurizing the intake manifold to see where pressure is leaking out. With the engine off the only path for it to leak out should be the intake valves.