Slartibartfast

Yours is just stuck together with maple syrup, eh?

A vacuum leak would make it run lean, not rich. Do you have a receipt for the injectors that the first guy put in? I'd be curious where they came from. I have heard horror stories of cheap aftermarket injectors that dump way more fuel than they should do. This would explain the rich condition starting right after that work was done. If you suspect the oxygen sensor is faulty, or getting bad data from air getting into the exhaust, you could rule it out by unplugging the sensor. If the computer knows it's not there, it just won't go into closed loop. It'll run richer than normal, but if bad data from the sensor is the problem, then it'll probably run better than it's running now. That's the flange at the Y pipe, right? Mine failed there too. I've heard of it setting the carpet on fire if it gets bad enough. Mine didn't go that far, but the floor over it was rotted through. The right way to fix it would be torching/cutting/drilling out the fasteners and putting it back together with new bolts, a new gasket, and maybe some exhaust sealant if the surfaces are too pitted to seal. And then there's the way I did it, which involved deciding I couldn't be arsed to deal with all that and instead welding the two flanges together. It doesn't leak, but I'm gonna have to sawzall it apart one of these days when I go after my rear main. Looks like Rockauto has an aftermarket Y pipe assembly listed, if you'd rather not mess with the old crusty stuff. I would still expect it to be a bit of a fight. I would also expect an exhaust shop would be able to sort it out, if you don't want to deal with it yourself. Unless you overheated the holy crap out of it, you don't need to worry about warping the block. It is possible to deform the flanges of the valve covers by overtightening the bolts, but it's also possible to straighten them out again with a little hammer, so that's not the end of the world. Neither fault would cause the rich condition that you are chasing.

I do not have a service manual that I know is correct for an Aus-market R50. This manual covers the US-spec 2000 R50. Hopefully they're largely the same, because that's all I have to work with. Your decoding of the flashes matches what I'm seeing, and the manual has detailed troubleshooting for each of these codes. The troubleshooting for the torque converter lockup solenoid (AT-148) shows its wiring going from the transmission computer, through connector M71/B51, through B64 (labelled "terminal cord assembly"), to a final plug at the solenoid itself. The wiring for the overrun solenoid (AT-188) and the line pressure solenoid (AT-162) go through the same connectors, and the same harness. Three circuit faults, in the same harness, going through the same connectors, makes me suspect a corroded/melted connector or damage to the harness. Unlikely that three solenoids all walked off the job at the same time. I would check the wiring around the gearbox, see if there's an obvious spot where the harness got smashed or something. Failing that, I expect that chasing any of those three troubleshooting procedures will lead you to the cause of the other two.

I have no experience to add here, but some old posts from Mr. 510 suggest that they all interchange, with the possible exception of the WD21 starter not liking the VG33ER flexplate for some reason.

Are you looking for an upgrade to the adequate-but-not-great stock brakes, or has something happened that's got your brakes worse than they used to be? I had a knockdown dragout fight with the brakes on mine a while back. IIRC the master was leaking, so I replaced that and the rear flex hose between the frame and the axle, and the rear brakes just kinda quit working. I did a bunch of screwing around. Two-man bled, gravity bled, reverse bled, deleted the abs, put a 2WD Hardbody master in it (same piston size but no internal prop) with a Wilwood external prop because I didn't think the prop in the aftermarket Pathy masters was bleeding right, even replaced the booster. None of it helped. It bled normally, nothing was blocked, and the bleeders were at the top like they're meant to be. With the rear axle on jackstands, in drive, at idle, both feet on the brakes, the rears just spun. I was out of good ideas, so I bought a brake pressure gauge, blew out all the plumbing for the rears with compressed air, and tested pressure at each point down the line, bleeding at the gauge as I went. Right at the master, joiner in the driver's wheel well, where the ABS used to be, splitter at the rear axle. Might've put it at the caliper hoses too, don't remember if I had the fittings for that. The gauge showed full pressure every time (~1500 psi IIRC). With no obvious fault to chase, I hooked the calipers back up, bled them yet again, and somehow the rear brakes started working. I don't know why. All I can think is there was a gob of goo holding an air bubble in a union or something, which all of my prior bleeding had somehow failed to budge. I still hate everything about brake fluid. Hopefully yours is easier to deal with than mine was!

Yours lived longer than mine did! I have no idea what that metal thing is for. It looks like some engineering went into it, so clearly they expected it to do something. All I know is, I did not include it or replicate it when I fabricobbled a metal clamshell for mine, and my tilt works normally, so it must be something else. The weight may not be helping the clamshell, especially cantilevered out like it is, but I suspect it's got more to do with people whacking their knee on the bulge that the weight sits in. Well, that and the poor design of the screw posts.

The service manual has the whole temperature vs oil weight thing on MA-9, but recommends 80w-90 for the diff unless it's over 104*F outside. I used 80W90 in mine, with some CRC posi schmoo because LSD. Your open diff shouldn't need any additives.

Can third that. When I did the rear bearings on mine (WD21, but quite similar), I had to buy a bearing splitter and a hydraulic press, and make my own special tool to deal with the big stupid splined nuts on the axles. It wasn't an awful job, but probably not one for the driveway, unless you've been looking for an excuse to buy a press. I did a video on it if you want to see me make it look harder than it has to be. (I probably should've done the first one before turning the camera on.) Annoyingly, replacing the bearings did not get rid of the noise that I was chasing. Mine was louder on turns, no change on/off power, so, not the same as what you're chasing. I've got a cheap digital angle finder that I use for checking camber. I'll bet it would do pinion angle too if you can find something on the yoke or the housing to set it against. Not sure how that would've drifted though, especially as you've already done the rear link bushings. Maybe if the trans mount was absolutely knackered?

I usually use nissanpartsdeal. Amayama may have stuff that they don't, though I have ordered stuff from them and gotten a "sorry, we don't actually have that" email afterwards, so don't assume listed = in stock.

The knock sensor in my '93 is wired the same as yours. Two terminals, only one pinned in the plug. The circuit diagram on EF&EC-99 agrees. The sensor must ground to the block. When I checked mine, chasing a knock sensor code, I did the same test on EF&EC-137, and like you I found no continuity. Annoyingly there isn't a spec for the sensor itself, but I noted that my old (bad) sensor read about 2 megohms across the terminals, and the new one read 558k ohms. The '97 manual specs 500-620k ohms, so the replacement was within that spec, for whatever that may be worth. If the knock sensor hears something that the computer doesn't like, the computer pulls timing (EF&EC-19). If the sensor circuit reads out of range, it'll set a code. EF&EC-23 says that if the code is set, it'll pull timing "according to operating conditions," which it does not elaborate on, so, . Mine seemed to get a little power back after I replaced the sensor, but that's just the butt dyno talking. I do not see anything in the manual suggesting that a knock condition (or a bad knock sensor) would change the fuel mixture. This means your rich condition is likely unrelated. I would suspect injectors (would be weird for all six to be bad, unless someone's previously swapped them for the cheap crappy ones that a few people on here have had trouble with), oxygen sensor (gets stuck reading "lean"), or coolant temp sensor. A bad temp sensor or corroded connector can tell the computer that the engine is much colder than it is, so it assumes higher air density than exists, and dumps too much fuel. I had a stumble just off idle and an intermittent failure to idle when warm on mine, which turned out to be the plug for the MAF. The sensor itself was OK, but the pins on the plug side were hogged out. Messing with the plug would clear it up for a while. I finally got sick of it and spliced in a new plug, and it hasn't done it since. I didn't notice any signs of a rich condition, though, and it ran fine so long as I didn't expect it to idle. Funny, I recently started my first rodeo with an EJ25. Timing belt/water pump/etc. Those valve covers look like fun.

I would start with the troubleshooting for code 32, EF&EC-93. (Download the service manual from Nicoclub if you haven't yet!) Rule out the vacuum lines (just replace them if they're original!), the EGRC solenoid, the EGR valve, whatever else the manual says to check. IIRC my '95 had a short hose under the EGR-BPT (the UFO-looking diaphragm deal beside/above the EGR valve) that had burned through on the back side, so I'd check for that too. There's also a test for the temp sensor. EF&EC-135 says to test the sensor at 100*C/212*F. It should read 85.3k ohms (plus or minus 8.53 ohms) at that temperature. If it was open or shorted, it would be throwing code 35, but it is possible it's just drifted far enough off spec that it's lying to the computer. The temperature it reads corresponds to how much exhaust is flowing through the EGR valve (more exhaust = more heat), so if it's reading low, that could make the computer think the flow is lower than it's supposed to be, causing your code 32. The temp sensor lives in the dirtiest part of the engine. Unless it's crusted up on the tip of the sensor like the corn on a corn dog, I wouldn't expect the soot to insulate it enough to matter. Might be worth cleaning it if you go through the rest of the troubleshooting without success, or if you have it out anyway, but I'd be surprised if that was the problem. Carbon buildup in the valve and/or manifold could also be decreasing flow. I've heard of the EGR on the old TBI engines blocking itself up completely. I haven't heard of the multiport (what we've got) doing that, but the EGR port in the manifold on my '93 looked like those "this is what cholesterol does to your arteries" posters at the doctor's office the first time I had it apart. (It wasn't coding, but it's the earlier/federal-smog system, with no temperature sensor, so the computer would've had no idea.) The unplugged sensor makes me suspicious that the PO might've been tinkering. I've read that you can get away blocking off the EGR on the federal-emissions trucks, because they don't have the temp sensor. Perhaps the PO blocked the EGR (either to bandaid a bad EGR valve, or because racecar yo), the temp sensor ratted him out, he unplugged the temp sensor, that didn't magically fix it, and then he sold it to you rather than fix it properly. Good luck!

Damn, they did all the connections to the door lock harness with Scotchlocks? That must've taken a while to unpick. Good work clearing it out, one less thing to give you problems!

SAS'd on portals! That thing isn't messing around.

My RMS needs doing too! It used to be a slow leak. 1. No special tools needed AFAIK. You can get the '90 factory service manual from cardiagn.com. The AT section has step-by-step instructions for dropping the tranny (AT-124), and the EM section has the same for doing the rear main (EM-20). 2. The gasket in the aftermarket kits goes between the retainer plate (which holds the seal) and the back of the engine block. Unless you're going to try and fish the seal out without removing the retainer, you'll need the gasket as well. I think I've got the Fel-Pro kit on the shelf for mine, don't remember--and of course I can't vouch for it as I haven't installed it yet. 3. I assume you'll need the gaskets for the exhaust crossover as well. You may need hardware or more depending on how much the exhaust fights you on its way out. These also tend to break exhaust studs (holding the manifold to the head), though I don't know that having the trans out would make these any easier to access. I would check breather hoses and exhaust hangers while you're under there. Might as well change the fluid in the transfer case too. 4. The trans cooler is a good idea. There are a few old threads on here with size and type suggestions. I don't actually know what mine's rated for, I got it secondhand and it's not marked. I installed mine in series with the existing cooler in the rad, and also added a Magnefine external filter while I was at it. If you just drain and fill, you don't get the old fluid out of the torque converter, so I did a flush through the cooler lines instead. Take the lines off the existing cooler, put them in a bucket, run the engine until fluid stops coming out, add that much fresh fluid to the transmission, do it again, repeat until what comes out looks more or less like what goes in. The trans fluid level is a bit of a pain to set. It has to be warmed up when you check it. If you set it cold, it'll be too high once it warms up. Either measure what you take out and what you put in and make sure they're the same, or undershoot a little so you have room to top it up once it's warm and you can check it properly. I thought mine was underfilled, warmed it up, and had to drain a bit back out of it. The manual calls for Nissan-Matic D, which is still available. From what I've read, it's basically just Dexron III, so I used generic parts-store-brand Dex-Merc, which was cheap and available locally. 5. Torsion bars are also a pain to set up. If you have to drop the bars (and the service manual suggests you will), mark, measure, or at least take a picture of where the adjusters are set and how the bars are clocked vs the adjusters. Otherwise you'll be screwing around for a while trying to get your ride height back where it was. I used spray paint to mark the adjusters on a friend's S10 Blazer when we swapped the trans, and reassembly was as simple as matching up the paint marks. This thread recommends filling the gap between the RMS retainer and the pan with silicone to stop mud from getting in there and causing corrosion. Seems like a good idea. Good luck!

The FE section of the service manual has diagrams of the exhaust system, and where all the mounts are. There's one between the pipe before the cat (off a U bolt in the '90 manual, off the cat flange in the later manuals) and the transfer case, one at either end of the muffler, and one on the tailpipe behind the muffler. You can get the '90 manual from cardiagn.com, or at least that's where I got it. I had a similar rattle on mine. It worried me at first, because it only happened under certain load conditions, making me think a U joint or something was on its way out. I found it by rolling under the truck and just whacking the exhaust with my hand until I found something that rattled. IIRC it was that U bolt upstream of the cat that had worked itself loose. The nuts wouldn't move, and the only problem it was causing was the noise, so I tied it up with baling wire and called it good. Given the crossover pipe has been out recently on yours, I would look especially hard at the fasteners and heat shields on that guy.