joshuaho96

it is possible, especially because you said the idle calms down when you disconnect the IACV. The torque converter has non-negligible drag even in neutral/park which is probably why base timing is advanced on the auto ECU. You may need to find some way to restrict airflow beyond what a dinky little idle screw can do. Possibly adjusting the closed throttle butterfly position, but that's a really big hammer for what could be a relatively small problem. I would only do that if you're 100% confident that everything else is correct and you're 100% confident that's the problem.

High idle shouldn't be caused by the ECU not seeing the transmission signal, but the fact that plugging in the AAC causes a major idle spike is a bad sign. At 1200 rpm is the AAC duty cycle 0-2%?

Are the ATS carbon clutches really all that good for street use? I was under the impression that the lack of springs in the clutch means it's much easier to cause shock loading of the drivetrain unless you take care to prevent it in how you drive.

Try an aerosol cavity wax like the one linked earlier, displacing water/oxygen will help to prevent the corrosion process.

Once you get logs of the issue feel free to upload it here, I can try and stare at it and see if anything stands out as well.

Should really be called the fast idle thermo valve, cold start air valve, or something similar that at least indicates that it's associated with cold start air regulation. My advice as I've been working through my own car is to get Nissan Datascan with a Consult cable and take logs when the car is misbehaving. You have to see what the ECU is seeing to understand why the engine is behaving the way it is. The ECU itself has very weak self-diagnostic capabilities, basically the only codes it throws are for things like open circuit/short circuit. All the sensor plausibility stuff is entirely on you to diagnose. How stable are AFRs when the engine stutters at idle? What does the MAF signal look like? Really meditate on the logs before you throw parts at the car. If you're suddenly losing consult cable connection during those drop-outs I would start suspecting the ECU or whatever is supplying power to the ECU.

Rear screen looks like it's one of the types with a metal hoop on the outside which causes it to stay up via tension against the headliner and the parcel shelf. Tint isn't a problem if you use a ceramic film but keep in mind that removing tint from the rear window especially is difficult and is what the mechanic was warning you about. Very easy to slice/rip up the rear defroster lines in the process of removing old tint, very difficult to repair such damage without replacing the glass. My solution has been to just keep the car garaged end to end but obviously in Japan this is a very challenging thing to do. In hindsight while the market seemed like it was crazy to you it clearly has only gotten more insane since you bought your car, so you were right to scramble for what you could while you could.

If they haven't tried to make things right despite giving them ample opportunity I would just post it here, no point in beating around the bush like this.

How well does a soft fuel cut work? Thinking about it in my head I can't imagine how you'd run on say 4 cylinders without causing a lot of weird vibrations.

If you're afraid of breaking oil pump gears there are some solutions that don't require pulling the engine. One is to use an ECU tune with proper soft limiting. The "best" method is DBW forcing the throttle to close, effectively idle control with the target RPM being just short of redline as long as the commanded torque from the APP is higher than the torque commanded by the rev limiter and engine RPM remains above the threshold for the soft limiter to kick in. I'm pretty confident this is actually the main rev limiting strategy used in a lot of cars these days, people complain that they can't bash the limiter in neutral anymore and instead the engine smoothly goes up to 3000 RPM and stays there perfectly. Another option is soft limiting by fuel or ignition. I have never tried a soft fuel cut, no idea how that would work without causing weird behavior like high engine vibration and wonky O2 readings from effectively a random misfire. Soft ignition cut can also help, but there is no free lunch there. You will cause EGTs to skyrocket this way, rely on this too much and it'll really do some damage. You really just want to take the edge off of the hard cut by smoothing the transition into and out of it to try and reduce the shock loading. You could also have high hysteresis on a hard fuel cut limiter. If you have to wait like 500-600 RPM before the ECU shuts off the rev limiter it'll be much harder to do a ton of damage compared to one that waits 50 rpm before going back to normal fuel/spark. This is probably very annoying though if you want to stay near the limiter for long periods.

I don't think dry sumps are inherently orthogonal to street cars, it's just that it seems to involve quite a lot headache if you want to keep the OEM power steering + AC compressor. I also wouldn't want oil lines running under the car all the way to the trunk and a big hot tank of engine oil sitting back there. My use case is going to be pretty much entirely street use, track use is secondary and the only goal there is to keep the car reliable and not scattering conrods to the wind, it doesn't really need to be quick so options like just running lower grip tires are on the table. I'm not a good enough driver to actually drive a car at 10/10ths without making the news anyways. I think there are front-mount oil tank solutions, it just involves something like deleting the washer reservoir and other similarly kind of unsavory compromises IMO. If I really wanted or needed a dry sump engine in a street car I'd probably just get one that has it from the factory.

It sounds like the solution goes something like sine or spline drive, upgraded oil pump, deep + baffled sump, maybe relieving the oil returns to improve the flow, a big external crankcase breather instead of trying to rely on the existing ones in the block, oil restrictor in the head, a lot of attention paid to the air/oil separation at the valve cover/before the compressor inlet, using the engine to help pull blowby out of the crankcase, and not trying to go full hero with semi-slick R compound tires. Also avoid blowby to begin with by using a torque plate, picking pistons/ring packs/etc that don't require loose clearances. If you want to go full race there are definitely dry sump kits out there. It's just a compromise, like anything in life.

You jest but a mystery floating around in my mind is this Nissan heritage page: https://www.nissan-global.com/EN/HERITAGE/skyline_gt-r_bcnr33.html Supposedly the R33 GT-R concept was going to have 405 kW crank power and 490 Nm of torque. What ever happened to that plan? That would've set the world on fire back in the day even if they only shipped 75% of that. My best guess is that they set that target internally but development budget limitations made it impractical and the 280 PS agreement would've been blown wide open even if they claimed it was only 280 PS.

It was a very different era. Look at a 3S-GTE of comparable vintage, if you throw an MR2 GT-S in the corners with modern rubber it will similarly puke oil from the breathers and lose oil pressure in similar situations. Same goes for a lot of wet sump cars. The modern expectation of being able to throw Michelin Pilot Sport Cup 2s on a car and drive it to 10/10ths for a production car lap record without blowing up an engine is very recent. The idea of shipping a wet sump engine with dedicated scavenge pumps, tons of thought devoted to oil return, air/oil separation, crankcase ventilation, etc is something that was really only thought of starting with cars like the R35 where the design spec was 1.6g for 7 seconds without losing oil pressure. In the 90s that would've been ludicrous when ~0.9g sustained cornering was considered a big deal, you might see peaks of 1.2g tops. Keep in mind that the reason why the gears have play is because too little clearance leads to binding which will cause a catastrophic failure. It is a pretty delicate balance. I do think Nissan could and should have thought harder about the oiling system but we're talking about a design from the 80s, we have the advantage of hindsight and orders of magnitude more computing power available at our fingertips.

Bumping this thread again with something interesting: https://deatschwerks.com/products/9-441-c102-0913 This is a 440 lph pump that is drop-in compatible with the R33, R34, S14, and S15. Pump flow/amp curve: The pump can take a boost converter to run up to 18V continuous, 22V intermittent. At 20V it'll flow 40% more than it already does at 13.5V. Pressure relief valve activates at 125 psi so you can safely run the pump up to 7 bar. I'm thinking of trying to make this pump work with the Bosch 997.1 Turbo 630cc injectors to run something stratospheric like 5 bar fuel pressure across the injectors in order to flow enough for E85 while retaining the DOHC 4V optimized injection pattern. It's a 52mm injector with extended tip though so I'm not sure the existing adapters out there would fit.

Q60/Q50 has EPS which isn't much to write home about, god forbid you have the direct adaptive steering system which disconnects the steering column from the wheel so you have zero feedback and some electronic controller silently doing steering inputs behind your back. The 400Z hopefully has some form of hydraulic power steering and a lot of refinement to make it less of an 8/10ths car as everyone seems to think the 350/370Z are. Either way, the VR30DDTT will be a throwback to the Z32 TT with its tremendously cramped engine bay.

Looking at the BaT auctions for these cars I don't think the collectors right now are really looking at engine numbers. Nobody buying these things cares about stuff like that when there are much bigger issues to be worried about like major rust problems, severely ragged out/damaged interiors, poorly done resprays, etc. Focus on condition and the rest will follow. Just swapping out an engine from late R32 to R33 is really a nothingburger when those engines are basically identical part for part. In 10 years who knows but I bet with all of the Adam LZs of the world doing big builds with no real concern for quality of work or maintaining the character and refinement of the OEM parts it will be even less relevant with such a slim pool of options for buyers. Just having a relatively stock good condition R32 GT-R VSpec II is already a very rare thing and will be even rarer in the future. I'm not really a collector though, I bought a grade 3 R33 and restored it so I could have something that I could drive. It's not very fun to have a car where you're terrified of letting your feet rub against the floor mats when you press the clutch in or you fret about driving in the rain because it might rust due to Nissan's sparse factory undercoating.

They'll give a good price, finger in the air estimate probably 80-100k USD.

I think the problem is more like because I don't drive the car very much E85 becomes a problem. It's about to do a ~550 km road trip down to the CA grey market emissions lab though, and I plan on doing some road trips like that out to the local tracks for some driving instruction in the future. Water injection seems far too fraught with landmines for me, far too many stories of injector problems and other headaches to really want to deal with it. As far as emissions and fuel economy goes I understand that a car that doesn't get driven very much doesn't really need to get good fuel economy or good emissions but it would be nice to improve those as well as achieving more power output than I otherwise would on ~96 RON CA gasoline. It pains me to think about how easily the engine gets into boost enrichment right now, obviously with a tune it'll do better but it's a long way off from modern GDI turbo engines that can go as lean as 0.9 lambda at ~3000 RPM WOT. Maybe retrofitting TJI becomes hilariously, wildly impractical but if it's really "just" a built bottom end, intake + exhaust VVT, a major revamp of the timing/fueling map to account for the different ignition delay/knock limit, and a weird-looking spark plug then maybe it's viable when I inevitably blow up my engine doing something dumb.

Yeah, I'm pretty sure this is the last gasp. I'm really only interested in looking into this because the compromises involved in E85 (only a few stations, major rework of the fueling system end to end, corrosive, significant range reductions) and water injection (reliability, oil contamination/piston wall scuffing concerns, finding space for a water tank + water lines, maintenance requirements, actually sourcing injectors that work well, etc). Passive TJI seems to be a bit simpler in that the fueling doesn't need to adapt, it seems like maybe it won't be a guaranteed silver bullet that allows for lambda 1 everywhere all the time in retrofit applications but it would allow for better timing + more lambda 1 operation.

It's been in development for like 10 years, half the paper is discussing their efforts to get this thing ready for mass production, there's a lot of "boring" stuff in there like warm idle control authority via spark timing, cold start catalyst heating, cold start combustion stability down to -8C, etc. They're also claiming that the impact of main chamber GDI vs PFI with this ignition method is reduced because there's a lot less time for spark knock to develop. I think OEMs are probably pretty interested in the idea if only because it reduces their costs/complication by eliminating GDI in the passive variants. I get the distinct impression that Mahle is trying to sell this to OEMs as a cheap retrofit, there's also mention of controlling the pre-chamber volume to get to the desired target pressure rise rate which sounds like it may help in cases where you can't just retrofit EGR or an EGR cooler. I think the real deal-killer is likely to be working around an extra 30% in peak cylinder pressure, it'd be interesting to know what kinds of bmep the RBs run these days and what kinds of peak cylinder pressures. This kind of improvement is pretty substantial IMO: The question I really have is more about VVT than anything else. When I look at the packaging of this engine in these cars I really don't see a viable method of recirculating exhaust gases externally. Is there some method of using VVT at high load to achieve internal EGR without adverse knock-on effects? I guess you could crank the boost?

Some kind of coincidence always seems to occur when I ask questions, it turns out that Mahle did study the delta between MJI vs MJI + LP-EGR: Maybe this is a lot more doable than it seems at first glance? The problem as mentioned before is that EGR is necessary at high load to control the rate at which the mixture burns to keep things within what a reasonable bottom-end can handle.

This isn't really an RB or Nissan thing but back in early April Mahle published a paper for the SAE WCX digital summit on their project with passive turbulent jet ignition. Active TJI has been used in F1 for a while now due to the fuel flow/refueling limits in those races. Passive TJI is kind of like active TJI, except instead of the complication of having a direct injection mechanism inside of a prechamber with a spark plug the passive system relies on the compression stroke to force fuel/air mixture into the prechamber, either via a main chamber direct injector or a port fuel injector. The disadvantage of this setup is that it doesn't allow for any lean burn tricks like the active version, but the advantage is that Mahle is claiming they've been able to get this passive variant to fit in the same footprint as existing M12 spark plugs: They include a nice photo of what a production variant might look like: HKS' prototype for comparison, which may or may not actually be functional: The primary driver for this research right now is the ever-tightening noose of RDE conformance (step 1,2,3, etc) which is making all the ICE manufacturers scramble to come up with solutions for how they're going to get a gasoline engine to never enrich under high load which is going to cause them to blow past the PM/PN and HC/CO limits set by Euro6d. Introductions aside, the real question is what Mahle achieved. This research was done against their 1.5L I3 testbed engine which achieved a peak of ~37% thermal efficiency and has all kinds of tricks up its sleeve like GDI, integrated exhaust manifold for fast warm-up, dual wide angle (60 crank degree of traverse) VVT, DOHC 4V head, 83mm bore, 92.2mm stroke, electronic wastegate on the turbo, etc. This is broadly kind of similar to the Honda L15B7 which also achieves 37-38% peak brake thermal efficiency in the sweet spot but tails off to pretty mediocre levels at WOT in the 5000-6000 RPM range, maybe 25% due to the boost enrichment: https://www.epa.gov/sites/production/files/2018-10/documents/sae-paper-2018-01-0319.pdf To convert this engine to MJI in a kind of drop-in application they changed the CR from 9.25 to 9.1, changed the engine to port injection only, added a low pressure cooled EGR system, and changed the turbo to a higher flow turbine due to the higher mass flow rate through the turbine from EGR. Cams remained pretty standard stuff, 246 degree duration for both intake and exhaust. One problem they noted here was that their first iteration of the spark plug had too much pre-chamber volume which led to extreme combustion rates, over 6 bar per crank degree. They ran a few different "shoot-out" experiments comparing this 9.1 CR engine with their passive TJI system to the same engine with a central spark plug to try and eliminate other variables. These tests had limits set like stoichiometric AFR for the full sweep, 98 RON pump gas, <950C EGT pre-turbine, compressor outlet IAT <180C, and <6 bar/degree pressure increase. The main takeaway here seems to be that within those constrains they were able to get more timing advance in the sense that the burn rate of the air/fuel mix is fast enough that even the same ignition timing results in better combustion phasing, with the 50% mean fraction burned point getting closer to 10 degrees after TDC which seems to be what they settled on as MBT for this engine. If you look at the the ~80 kW/L load point at 5000 RPM it's almost 5 extra degrees of timing. The big caveat here is that maximum cylinder pressure is at least 20% higher than the central spark plug which the bottom-end has to be designed for. The engine also needs a pretty tremendous amount of EGR to not run boost enrichment: I think this chart sums it up pretty well, the engine used in this fuel vs timing/EGT/etc chart is a different one they made for a different paper (miller cycle, 172 degree intake cam, 14.7 CR) shows that ~90 RON with passive TJI gives you better timing than 95 RON with a normal plug, and 95 RON gives you better timing than 99 RON with a normal spark plug. The big question in my mind is just how relevant this is to an old engine like an RB26. It sounds like cooled external EGR is a pretty central part of being able to realize full stoichiometric operation from these results, what kind of results would result from VVT-based internal EGR?

I've heard of some people stopping the rust by using a needle to inject lanolin oil/grease, if you get rid of the oxygen in there it can't keep rusting.

From what I can tell Nissan was actually somewhat less cheap about rustproofing on the R32s compared to the R33/R34, my car was worked on almost simultaneously with an R34 and it was pretty striking to see how even from the R33 to the R34 you could see a reduction in applied undercoat to save those few pennies. I don't really know that the R32 has those kinds of guaranteed rust spots like the cowling area, A-pillar drainage areas, fuel tank mounting points, and front strut towers. From what I've seen though rust tends to crop up in places like where the door/hood hinges connect, rocker panels/pinch weld areas, etc.