joshuaho96

It is possible to refurbish the cooler, in the US at least we have some oil cooler service companies that are mostly specialized in aviation and are FAA certified. Those oil coolers are usually huge, huge money because everything in aviation is. They flush the cooler under pressure and high temperature + ultrasonic it until they verify that the cooler no longer sheds debris.

Like I said earlier, it's smaller than stock. You can just look at the numbers and compressor map to know this. Technically the turbine will flow more due to higher trim but the compressor flows less air at the same pressure ratios.

The GT2560R is quite literally the factory 91F00 S15 turbo. So size appropriately from there.

Every time I reach under there I have accepted that I'm shredding my gloves. Too many hose clamps and other sharp bits.

He already asked this question earlier on a Facebook group, I have the same turbos and in 4th gear it should be at 10 psi around 3200 RPM. Uneven compression across the the cylinders is not a good sign, especially by that much. I would also question the cam timing, it's possible the cam centerlines were not cut correctly or some other issue with the aftermarket cams, supposedly Brian Crower has QC/QA issues.

https://www.ozwidetools.com.au/nissan-toyota-valve-lifter-bucket-shim-adjusting-t Not sure if there's better options but this is what I found with a quick search. I found the full R34 service manual here: https://www.facebook.com/groups/gtrusa/files/

Isn't the RB25 NEO a shim over bucket engine? In every shim over bucket engine I've seen you use a special service tool to depress the outer rim of the bucket and then use a magnet and a thin plastic spudger or something similar to pull the shims without undoing the cams precariously like you did. When I check the R34 service manual that's also what it depicts:

Yeah, it's very contextual. If you have to add a bunch of plumbing and general annoyance to "do it right" then I also wouldn't bother. On the RB26 venting directly to atmosphere means capping another port on that combo vaccum/coolant pipe under the plenum and figuring out how to keep track of a random hose/hose clamp 5+ years into the future. I have a mystery "firewall harness bolt" sitting in an organizer and it's taking up a non-trivial amount of my mental headspace trying to work out which of the five or so cars it could possibly have come from.

While true, it's just easier IMO to put the hose on the solenoid instead of pulling it off and then forgetting it somewhere.

Turbo pressure line is the green line from the plenum. Almost all diagrams online just vent to atmosphere which is why you're confused. This is fine on speed density systems but it will cause an unmetered air leak on MAF-based systems. Even if it's nominally ok you really don't want to make a habit of it because it just makes it harder to diagnose what's wrong in the future.

No, look at this diagram again: What you have drawn would put boost into port 1. The blue section is the intake before the turbos but after the MAFs.

The blue line is not boost. It is a vent to atmosphere. The green line going to the plenum is the boost source. My original diagram already shows what you need to cap. You only cap one pipe on the engine and then re-route the hose to go to the boost solenoid directly. The rest is unchanged.

Factory solenoid is 2 ports only as others have said. To make a two port solenoid work you must tie the wastegate line to the plenum (boost source). That way when the solenoid isn't working the engine just makes wastegate boost. Then when the solenoid activates it vents to atmosphere (blue line). When you vent to atmosphere the problem with a 2 port solenoid is two-fold. First, it's a boost leak which is annoying. Second, you really want the pressure experienced by the wastegate to be as low as possible. With a 2 port solenoid the wastegate line will always see a pressure higher than atmospheric because the turbo's boost is bleeding both to atmosphere and into the wastegate line. The 3 port splits the two states. Either you are sending boost pressure to the wastegate line (solenoid is off) or you are venting the wastegate line to atmosphere (solenoid is on).

No, not the manual transmissions. I have to check for the automatics but most likely instead of sending coolant under the car to the transmission oil heat exchanger they would send transmission oil lines going forward into the radiator instead.

Not sure I can make it any clearer than this. Notice how one of the hoses has a restrictor from the factory. Either cut it out, work it out with lubricant, or make a new length of hose without it.

whoops

I'm a big fan of more advanced modeling so it's easier to constrain the problem and there's less opportunity to shoot yourself in the foot. As OP mentioned you know when you're really screwing something up when working with a VE model if the numbers don't make any sense. 100% VE at idle for example. X-Tau constrains the problem of transient throttle such that you're only picking a wall-wetting constant and time constant and everything else just flows out from there. If your wall wetting constant or time constant is some ridiculous value you know you're doing it wrong.

I guess the correct distinction is VE vs injection time, regardless working in injection time is just kind of a pain. It's kind of like old style transient fueling vs x-tau.

I'd have to look at the series 2 in specific but when I worked with the EMS-4 in AEMTuner it did not work in speed density. Yes it uses manifold pressure as a load signal and there is an IAT/CLT sensor that is used to adjust fueling but all the tables ultimately operate in raw injector pulse width, it has no conception of volumetric efficiency.

Did you actually inspect everything under the plenum? The area at the back of the engine is a mess of coolant pipes. There's a Y-pipe for coolant return next to the wastegate vacuum pipes which can pinhole leaks from corrosion or mechanical stress cracks the weld/brazing for the joint. Also the rear block fitting for coolant could also leak. It also has a Y-pipe as well. As others have said it is also possible that the core plugs have corrosion so they're leaking coolant as a result. You can try to fix it with RTV but getting access especially for the back of the engine will probably require engine removal. Edit: Pic to show what I'm talking about:

Weird to me how the mechanic didn't offer to just tear into it further at that point but that's just how it rolls with a lot of mechanics. They'd rather get the cashflow sooner than later.

AEM hasn't even supported the series 2 in a very, very long time. To my knowledge it doesn't even support speed density. AEM has completely exited the ECU market as well. The last ECU they shipped was the Infinity and frankly speaking it was a buggy mess, the linked thread shows some things but my personal experience with it was not great either: https://www.miataturbo.net/aem-59/aem-infinity-piece-junk-lets-find-out-together-91346/

I have experienced what I would describe as idle dropping out in moments with counterfeit spark plugs but it wasn’t really idle hunting. It felt like a misfire almost. It would drop and then recover as the idle control caught it. Never stalled but noticeably felt strange and was fixed with new genuine plugs.

If you want to run the stock regulator you need to keep some method of making sure you aren’t trying to flow 255lph of fuel at idle. Otherwise you will experience what you’re talking about.

Idle hunting is a sign of air leaks. It usually means the ECU is trying extreme measures to stay on target idle speed. Easy way to validate this theory is to unscrew the TPS adjustment and tweak it ever so slightly to bump the TPS voltage above idle. This will disable idle control. An engine without vacuum leaks either internal or external should experience a low idle or no change in idle when you do this.