joshuaho96

Interesting, anything you'd like to say in detail?

I personally value the parts that a VSpec gets because I have no plans to actually modify things like the suspension or rear diff. The question you're asking is how many people actually value those parts. Judging by how often these cars have aftermarket diffs and suspension all that's left is two underbody covers basically. Value is relative. To some people the mechanical diff is actually preferable in the base model because it means no A-LSD errors or other nonsense to deal with when you rip out the factory A-LSD found in a VSpec.

If actuator preload doesn't fix your problem it's possible that there is excessive wastegate bushing wear which will require pulling the turbos to fix. Not sure if that's a common issue with these cars though, it's mostly notorious in the BMW N54 turbos for whatever reason.

It's swings and roundabouts. Doesn't matter that much. The earlier VSpec 1 has slightly better undercoating from the factory, the headlights still have the level adjustment motors, small touches like that. Series 2 base model gets slightly improved brake bias. Focus on condition. Only worry about VSpec vs base if you actually care about the bits that come with the VSpec like the front diffuser, rear diffuser, A-LSD, and slightly stiffer OEM suspension.

I'm surprised setting preload can be done on the car, factory service manual procedure has a specified measurement method for it and it looks like it has to be done with the rack out of the car. I had a tiny, tiny seepage coming from that adjustment and I ended up just ignoring it because I didn't want to mess with the adjustment at all.

Exhaust backpressure alone is not going to make you lose half of that spring rating. Anyways, if you really do have some HKS turbos in there you don't want to be running a lot of boost regardless. It's not that hard to max out the factory MAFs. Edit: We've had this discussion before two years ago, my answer still remains that you have some kind of mechanical issue. If you had a boost leak before papering over it by running max bleed on the wastegate vacuum line isn't a good idea.

The R33 GTR manual specifies 8.56 psi minimum to crack open the wastegate, purely spring pressure. It's not significantly different from the R32 GTR. Something was already wrong, it's just more wrong now. A 0.3 bar spring would only allow for a theoretical max of something like 0.6 bar boost.

I haven't measured the wastegate solenoid duty cycle but a local near me had something similar going on with his RB26 where the previous owner looped the wastegate line to atmosphere. It pegged the stock boost gauge. Once he capped the wastegate line so it no longer vented to atmosphere he ran wastegate boost. If you have any doubt that your ECU is not tuned for the turbos your engine is running you should run wastegate boost. The factory ECU has narrowband O2 sensors. It doesn't know anything other than roughly stoichiometric but it will adjust how much fuel it injects based on that information. If the short term fuel trims to hold it around stoichiometric are reliably offset in one direction that feeds into the long term fuel trim. If the long term fuel trims out are of spec that will tell you that you have some kind of running issue like unmetered air leaks. One broken turbo can lead to the engine make some boost. It will be noticeably less but still some boost. Also, if the turbo bearings let go from a boost leak you need to stop driving it sooner than later. Turbo failures often cascade into whole engine failures.

Definitely if you didn't have a screw loose already these cars will make it happen.

First, if you deleted your boost solenoid what is your vacuum line routing for the wastegate? I have personally seen people do the exact opposite of what they need to do to run wastegate boost when deleting their boost solenoid so this is an important question. Also I recommend checking for boost leaks starting after the MAFs. Second, what do your fuel trims look like? Long term and short term. If it's off by more than a few percent you still have problems. Third, have you inspected the turbos? Turbo failure can start with not making boost.

Good to hear you got it fixed. Sounds like a case where there was no one problem, just a bunch of issues all around. For reference in the future the way idle control works is the ECU is monitoring engine RPM and adjusts AAC duty cycle to suit. If you have some kind of vacuum leak that means the AAC can't adjust the idle properly then it falls back to pulling ignition timing out until it hits a limit. Once both of those methods have failed it basically starts cutting fuel injection momentarily to try and control the idle which causes that characteristic idle fluctuation. Idle drops from the fuel cut, then races back up the moment fuel injection resumes and the cycle repeats. I'm willing to bet if you logged injector duty cycle you would see the characteristic on/off behavior I'm talking about. The ignition timing going all over the place is likely a reaction to the engine RPM changing. There is some logic to try and catch a falling idle with more timing but once it gets too far from the target it will stop trying and hope for the best.

If there’s no coolant passage in the series 2 that really leaves very few if not zero possibilities other than head gasket. In 3rd gen Priuses head gaskets start by failing ever so slightly and causing a rough cold start as the coolant has to get burned off.

I took the time to stare at the technical data sheets more carefully, Loctite 518 is more tolerant of bad machining. Both are supposedly fine with a 0.25mm gap but 518 has a lot more shear strength than 515 in that scenario. Both have comparable engine oil tolerance but only 518 is specifically tested for ATF tolerance. 518 actually has less shear strength at 100C than 515 assuming you have that 0.05mm maximum gap. If the 515 fails to seal I would try the 518 and see if that improves anything.

I can only go off of the factory ECU logs but a pretty stock RB26 will warm up the coolant in about 400 seconds to 76C from 20C and another 60 seconds to get to 80C. So 6-8 minutes if coolant temps start at about 20C. Oil is probably 2-3 minutes behind, hard to time it exactly because I'm looking at a gauge instead of nicely time aligned charts sampled over Consult. Also, when the engine is warmed up the power steering idle up switch triggers a straight 8% bump in AAC duty cycle but when the engine temps are cold it's 7%. Not sure why there's this temperature dependence but that's what it is. I only park hard and hypermile my cars so this sounds like way too much effort, that is a really cool solution to the problem though.

Kind of surprising that they start with fuel cut to a cylinder, I would have figured adjusting timing within a range would be the primary strategy. Maybe that causes excessive EGTs?

The QG18DE does have coolant in the intake manifold. Most QG18DEs do not have EGR, only California emissions models and comparably strict emissions regimes would have them. Even then none of them have an EGR cooler so no coolant would make it into the engine from the EGR system and it wouldn't get into the oil that way either, any more than you would from the intake manifold leaking. There is no coolant in the exhaust manifold or anything like that, this engine is pretty straightforward in that regard. Theoretically it is possible that your intake manifold is causing all of these issues but I kind of find it hard to believe. Pressurize the cooling system and see if you can hear that pressure coming from the intake manifold. Or get a camera snaked in there and see if there's coolant pooling in the intake manifold. You can also try pressurizing the cylinders, if you have a blown head gasket it should end up either in the valve cover or pushing out the radiator.

I’m pretty sure from what I recall of this if you bore to standard RB26 size the cylinder walls are no thicker than a normal RB. If you want a simple solution just get a PRP block whenever they release that.

The issues you're describing here is kind of why I want to have a fully integrated ECU. Also pulling fuel even if it's a hard cylinder cut seems unwise from a harmonics perspective. Maybe it's no worse than an I5 or I4 done right but I'd rather do DBW to control it. Boost by gear and tuning the power delivery can also help avoid generating all that boost/power your chassis realistically couldn't handle either.

At this point why bother trying to buy an R32 ECU + Nistune board + Nistune license when that gets you most of the way to a Haltech E2500 or Nexus R3? I'm probably biased though, I decided I would rather put the energy into trying to do a true port of the factory tune to Haltech rather than mess with Nistune.

When I searched up that part number it was literally a tube of Loctite 518 in a Nissan box. I'm just not sure what the difference is between 515 and 518. Both are anaerobic sealants with similar methacrylate base. As far as I can tell it's just a color difference and 515 needs a longer cure time.

AFAIK the OEM sealant is actually Loctite 518, listed as p/n C133531X25 if you buy it from Nissan. Checking online I do not see any paper gasket or anything like that for the actuator: https://nissan.epc-data.com/skyline/bcnr33/3935-rb26dett/trans/333/30570X/

Yes, you should be concerned. How concerned? Don't know. Poke a screwdriver and see how deep the rust goes. If it makes a hole you need to weld in new metal.

Yeah, plan is to run a bunch of sensors and try to develop a good tune + engine protection and do a lot of logging during track conditions to quantify things like what the stock sump can handle in terms of lat/lon g, then start empirically testing things like additional sump breathers/accusump to see how much it helps. I would rather not discover exactly how consumable a block can be but anything could happen really considering I've only done dry compression tests.

Probably not, but I'm planning on doing it every so often if only to verify the car doesn't fall apart in those conditions. Not sure how else I could test things like whether the oil system can handle the Gs and whether thermal management is good enough for extended track use. To really get extensive track time in I'd probably just buy a Miata or a Corvette instead of something that overheats within 5-10 minutes of hard track use stock. Sure, but seemingly half of the people in my area with Skylines have blown their engines and mired in that whole quagmire for years at a time. I'm pretty confident I still have all stock oil pan so that's going to be an ordeal I'm going to have to face at some point. Would really be nice if pulling the oil pan on the RB26 didn't require dropping the whole subframe out with the engine dangling precariously or pulling the engine out.