Slartibartfast

HA-14 of the '99 manual says this is normal. The compressor varies its output internally (swash plate design) to keep the system at the required pressure, so it doesn't have to cycle. Looks like it only disengages if the HVAC is turned off, if it's too cold outside, or if there's a gas pressure issue.

Is that 12.7 on the fat wire from the battery, or the signal wire?

I removed it! The alarm was added after the truck was built, so it's pretty easy to take out, though you will have to pull some trim (and the driver's seat) to get it all. Most of it is just plugged in between things, so with it gone, the truck's harness plugs back into itself like the alarm was never there. The brain is under the driver's seat (square, white sticker on top, or a round hole with a button underneath if the sticker is gone), and its harness runs along the edge of the driver's side carpet to the A pillar, where it intercepts the power door lock wiring. Then it goes up into the column, where it intercepts the ignition switch. There are additional wires scotchlock'd into the park lights and dome light circuits, another plugged into the horn wiring, and a few wires through the firewall for the siren and the hood pin switch. These can all be cut, but if yours has fog lights, those wires are run through the firewall along with the siren wiring, so don't just chop that whole bundle. If you just want to bypass the alarm's control of the starter motor, you could just bypass it at the ignition switch (unplug ignition switch from alarm harness, unplug alarm harness from main harness, plug ignition switch into main harness) and be done with it. That would also take out the alarm's power source, so it would be effectively abandoned in place. Should work just as well. I was just done with mine and wanted it all gone. (I had previously bypassed the starter kill at the alarm end of the harness, and I was still having issues, so I knew the problem had to be in the harness or its plugs.) That's how it was on the four-doors I've been into. May or may not be accurate for your two-door. The service manual doesn't even mention this system, and the only service bulletin I've found that covers it (NTB93-036) only mentions '93. If it's got an aftermarket system, it's probably wired into the same things, but less delicately. If in doubt, follow black/yellow from the starter, and look for butt connectors, electrical tape, and Scotchlocks. I've got a paper copy of the '87 service manual, so let me know if you need a wiring diagram to put it right.

Accessories coming on means you have power to the ignition switch, and the accessory contact in the switch is working. The starter contact in the switch could still be messed up. Remove the steering column clamshell (carefully, they're brittle) and find the switch. It's on the ignition cylinder, opposite end from the key. It's got big exposed solder joints, so it's easy to test. Using a test light or voltmeter, check between where the black/yellow stripe wire connects to the switch and ground. You should have power there when the key is in the start position. If not, the switch is bad. Cheap part, easy to replace. If that's not it, there are some other things between the switch and the starter that could be acting up. Sounds like you tried the inhibitor relay already. Is yours auto or manual? If it's manual and 4x4, there should be a rocker switch on the dash that says "interlock." This bypasses the clutch safety switch, so if that's what's failed, flipping the switch should let you start it. If it's auto, try starting it in neutral instead of park on the off chance the inhibitor switch is playing up. I don't know if '87 had a car alarm or not, but that's what made the starter circuit act up on my '93.

I'm impressed it ran at all at 60* out!

At least it's not a telenovela. I don't remember enough Spanish to deal with that. I'd be surprised if an actual repair shop had one! A speed shop might. Seems like it would be easy enough to build one, but that's probably overkill just to laugh at an $11.67 injector pissing gas like the Sprite nozzle on a soda fountain. You might be able to redneck it, similar to one of the tests you suggested above--turning the distributor to make the injectors fire--but with the fuel rail propped up, out of the intake, with cups under it to catch the fuel. You wouldn't be able to check that the flow rate was correct, but you would be able to see if it's the same on all six, and check the spray pattern. Make damn sure the coil is unplugged from the harness if you attempt this test! IIRC the injectors fire in batch rather than sequential during startup, so don't be surprised if all six spray at once. Speaking of redneck, I saw a Hoonigan video a while back where they cleaned an injector with carb cleaner, a tire valve stem, and a 9v battery. Something to keep in your back pocket in case you find a stuck one or a bad flow pattern. Any fuel that was down the cylinders has probably either evaporated or run past the rings into the crankcase by now. Doesn't hurt to make sure, though. And yes, proper JIS drivers are a thing of beauty and a joy to behold.

There's a special tool for testing injectors. It's basically a fuel rail to feed the injectors, a circuit to drive the injectors, and a row of graduated cylinders for the injectors to spray into. The machine pulses the injectors, and the cylinders collect the fuel. While they're pulsing, you can confirm that the spray pattern looks good (nothing obviously clogged or dripping). When they stop, you look at how much fuel has collected in the cylinders. If you know what the injectors' flow rate should be, and you know how long they were open during the test, then you have your spec to check them against. Without that special tool, you could still check the flow rates against each other, but this would only tell you if they're consistent, not if they're correct. I guess you could swap one known good factory injector in place of one of the new ones and run the test again. Have you checked the spark plugs? Are all six spark plugs black or gas-soaked? If they all look rich, then either all of the injectors are wrong (which would make sense if the flow rate on your new set is incorrect), or a bad sensor reading is making the computer inject that much fuel on purpose (likely coolant temp). If only some of the plugs are rich, that suggests you've got bad injectors on those particular cylinders. The OE injectors have colored dots on them. I do not know what changed between the various colors, but it sounds like some of them may have different flow rates. I think blue dot and black dot are just different spray patterns, because some previous mechanic replaced one of mine with the wrong color, and it doesn't seem to care. But, yeah, ideally you want a matched set. My VG33 (which was previously swapped into another WD21, so it has the VG30 intake) has VG33 injectors in it. Different electrical connectors, but the same flow rate AFAIK. Not sure if that's the same thing you're looking at with the Z car injectors. But if you've got the injectors that the VG33 came with, I'd give those a shot. I haven't had to source an injector yet, so I'm no help there. I think @gamellott replaced one recently.

Painting a car properly is expensive and time consuming, and then you wince every time a bird craps on it. Unless the old paint has a message from your ex scratched in the side, or you know a guy at the body shop, I'd leave it alone. What about a wrap? I haven't priced it, but I'm guessing it's cheaper than paint, or people wouldn't do it. Chrome wrap is a thing too, if you want to do the bumpers. And if you don't like it, you can peel it off afterwards. But yeah, probably better to focus on the clapped internals before the clapped externals. Chrome vinyl wrap won't get you home.

So it sat, an injector failed, you replaced the injectors, and it hasn't been right since. I'm suspicious of the new injectors. If one or more are dumping fuel, that would explain the diluted oil (runs past the rings), the rough idle (because the flooded cylinders aren't contributing much), and the smoke. I'm also remembering the issues Cuong had with a set of cheap injectors a while ago. And how old is the gas it's trying to run on? If it's the same gas that's been in there since '21 (or before?), pull a fuel sample. Don't worry about the cam jump. Mine did that too. No harm done, apart from making me nervous. If you'd kept spinning it around, found a hard spot, and forced it past that hard spot with a breaker bar, then yeah, that would be a problem. But if it just jumped, and you rolled it back the way it came, then no, that shouldn't have hurt anything. I had a similar head scratcher with the distributor when I put mine back in. There were two spots that were close, but both seemed like they were half a tooth off. In the end I just picked one. I had enough room from there to adjust the timing to the spec'd 15 degrees. If that hadn't worked, I would've restabbed it to the other position and tried again.

Good, there's that ruled out then. Might still be worth checking cam to crank on the off chance. Looks like you're right about the bolts too. Been a minute since I did mine! If the hole lines up, and it looks like it does, I'd say you used the right gaskets. I don't see anything else weird in the pictures. Cam sprockets are on the right way around. I don't remember exactly where my rotor was pointing, but I remember trying it a tooth one way and then moving it back before I was happy with it. If it's pointing to where #1 is supposed to be on the cap, it should be good. I'm assuming you've checked ignition timing. How weird is it running? And what all has happened since it ran right?

Congrats on the milestone of working steering! Feels like this thing's getting close.

I think you're a tooth off between the cams. Should be 40 belt teeth between the cam sprocket dimples. I think I'm seeing 39. (Tough to tell, though--that lower right pic doesn't quite show the driver's side dimple.) Verify 43 belt teeth between the driver's side cam dimple and the crank dimple while you're at it. Don't worry if this puts the sprocket dimples a little off from the marks on the cover. Mine didn't quite line up either. The tooth count has the final say. I suspect a disagreement between the two led to that second white line drawn on the belt, and the belt being a tooth off, and the engine running poorly. I see the fasteners that hold the rear timing cover to the intake are missing. Do the holes for those not line up? The VG30 intake gaskets are much thicker than the stamped steel VG33 intake gaskets, so if you use the wrong ones, a lot of stuff doesn't line up properly, including those holes. I found this out the hard way on mine when Rockauto sold me the wrong parts. Mr. 510 also ran into this issue on his VG34 build, so even if it's going on a VG33, the VG30 intake still needs the VG30 gaskets.

+1 for checking the sunroof drains. I ran with no outer seal for quite a while and never got water inside.

For coolant to leave from the top of the rad, it would have to enter from the bottom of the rad. If the tstat is closed, the lower rad hose is blocked, so suction at the top of the rad would have no effect. Like you're sucking on a straw with the end blocked. If the tstat is open, the pump is sucking coolant through that bottom hose. So now there's someone else sucking on the other end of the straw, and they're better at it, and man that got weird fast. So there's either a deadhead or suction at the bottom of the rad, and an unrestricted supply of coolant coming out of the engine at the top. The datalog could be interesting, but leave the two-wire sensor alone and use the one-wire sensor for the dash (with the wire to the dash unplugged) instead. Two circuits trying to check resistance across one sensor could end badly, or at least give weird and unreliable data. And yeah, at this rate I'm gonna end up with a full backup of Nico's service manual collection on my hard drive. Sometimes it's worth it, though--last night I stumbled on the "body sonic system" in the '84 ZX manual. Looks like it had kickers in the seats, hooked to the radio. Butt subs. Oh, and RE convection. Some early cars and tractors did not have water pumps, and relied entirely on thermosiphon cooling. Heat rises in the block, cold falls in the radiator, coolant circulates. It even kinda works, mostly.

Hot coolant naturally rises over cold coolant. So even though there's no flow directly past the sensor when the tstat is closed, the warmer coolant will still make its way to the top of the system, which is why they put the temp sensor there. That sensor location is also why the heater core and intake warming circuits run back to the cold side. Both of those circuits are dumping heat, so the coolant coming out of them will be cooler than the actual engine temperature. If this cooler coolant was introduced to the system at the top, it would mix with the hot coolant around the sensor, giving the computer an inaccurate idea of how hot the engine was. Figuring out the rest of the coolant flow was more difficult than it had a right to be, mostly because flowcharts were a terrible way to try and explain this system, but also because Nissan doesn't seem to understand them either. Now that I'm really looking at them, the flowcharts in both the '95 and '87 manuals are just straight-up wrong. They show the water pump only being fed when the tstat is closed, and the tstat and rad forming a loop on their own, sans pump and engine, when the tstat is open. So, yeah, that ain't right. The Fronty flowchart makes a lot more sense. To confirm that it's the same as the VG30 cooling system, I pulled up yet another manual, this time for the '85 300ZX (which also had a SOHC VG30). That diagram looks very similar to the Fronty diagram, apart from the turbocharger of course. So, yeah, near as I can tell, that Fronty diagram should be correct for this application. It looks like the end of the thermostat is what blocks off the bypass hose. So as the thermostat opens, it's allowing more flow from the radiator, while throttling flow from the bypass hose. (Kinda like the hot/cold mixer knob in a shower.) This one-wax-motor-moves-two-valves thing would've been explained much better in a cutaway than it is in those stupid flowcharts! I did find a cutaway in the '93 300ZX manual, so check that out if you're struggling to visualize this--though that car has the DOHC VG, and I don't know what else changed on that variant, so don't trust it too far. Hopefully that explains it! I did not expect the rabbit hole to go that deep, or the rabbit at the bottom to be that vicious. I wonder if the borked flowcharts were drawn by the same guy who copy/pasted that fuel pressure test. (For those who don't know--the fuel pressure test in the WD21 service manual mentions a fuel pressure regulator control system, which was not fitted to these, but was present in some early 300ZXs.)

My bad, I was thinking in VG30! The pulleys on mine are bolted to the balancer. Looks like the VG33 combined the two so you can't mess it up. No idea why the marks are in the wrong place then, unless you've got the timing light on the wrong plug wire, or the rubber in the balancer has let go and allowed the pulley ring to slip. Good to hear the mileage is back up, at least! The noise could be a lot of things, and I don't know the R50 engine bay too well. Run it without the belts (briefly) to see if the noise goes away. If it does, check the bearings in the accessories and the idler pulley. Could be one of those singing the song of its people.

It is built like an electric choke, but no, it does not mess with the mixture. Just the idle speed. The IACV raises the idle by giving the air blocked by the throttle an alternate path into the manifold (bypassing the throttle). This has the same effect as opening the throttle slightly. In fact the VG33 does exactly that, using a wax element (like what's in a thermostat) to prevent the throttle from closing fully when it's cold. Warm idle also bypasses the throttle body, but is controlled by the computer. I don't know why the two systems are separate. None of this should change the air/fuel ratio. The air that the IACV (or the thermo element) is letting into the intake manifold still has to go through the MAF sensor, so the computer knows about it, and will maintain the mixture accordingly. (Also, sorry for the radio silence on your wiring question--will get back to that soon!)

It sounds like your poor truck has a big pile of comorbidities going on here. The pulley can bolt to the balancer six different ways. Sounds like the last guy put it on wrong. Fixing that will bring the marks around to where they should be. Make sure you set the timing with the engine warm. The IACV's entire job is to mess with the idle. If it's stuck wide open, or some muppet adjusted it wide open to try and mask another problem, that would make it idle high. A vacuum leak elsewhere could do the same. Adjusting the IACV would be my last resort unless I had reason to believe that it had already been messed with. I would run down the troubleshooting for the IACV code in the service manual. The manual should also have instructions for adjusting the IACV properly. Loud noises under the valve covers are concerning. I've heard of the cam retainer bolts coming loose and chewing stuff up. Something to check when you have the covers off, if not sooner. Might even be timing belt slap if the guy who left the water pump bolts loose was the same guy who installed the tensioner. And yeah, I'd be shopping for head gaskets--or possibly a used engine.

The different compression on each bank makes sense with how the timing was screwed up. Now that's fixed, I would check the ignition timing. If someone messed with that in an attempt to get it running better with the cam timing screwed up, it could be way off, which might explain both the overheating and the awful fuel economy. Oil in the overflow is not a good sign. Are you sure it's oil? The inside of mine's got some rusty crap in the bottom that isn't hurting anything. If it's on top, then, yeah, that ain't good. Best case someone put something stupid in there (either trying to clog a leak or just topping it up with something that wasn't coolant), worst case... I guess a head gasket could fail between the oil port for the top end and a cooling jacket, but I don't think I've heard of a VG doing that. Good that there's no exhaust in the coolant. Any butterscotch pudding under the oil cap? A while back I checked out an R51 with SMOD (ATF in the coolant). The gasket on the radiator cap had swelled so much that I had a hard time putting it back on. Yours doesn't seem to have done that. Did you use fresh coolant after replacing the pump? And did it look like this before? Make sure the cooling system is properly bled! There's a bolt for that on the upper intake. (If you didn't bleed that after doing the rad, the resulting air pocket may have something to do with your current overheating.)

LOL yeah, there are still plenty of reasons to question the engineers on these. The steering linkage, the strut rods, access to the #6 spark plug...

It is nice to have a few manuals to play off each other! The '87 in particular has lots of weird first-year stuff that's not in the later manuals, including a just-different-enough-to-cause-problems engine diagnostic code table. Nissan also put the tstat on the cold side of the KA and the VQ, and Chevy did something similar on the LS V8s, so clearly there was some kind of thinking behind it. I have not found anything that explains what that thinking was. My best guess is that mounting the tstat lower means it's not sitting in the hottest water in the engine, so it's opening later, helping the engine come up to operating temp quicker (which is better for fuel economy, engine wear, and of course emissions.) But that's just a guess. Whatever effect they were going for on the VG, I guess they decided there was some meat left on that bone when they drew up the VQ, because it's even weirder. They still put the tstat on the cold side, but they also split up the coolant outlets for the block and the heads, which let them put a second tstat on the hot side of just the block.

Nope! Other way around. Hot coolant passes from the engine to the rad via the upper hose, and cooled coolant returns via the lower. This is the direction in which the thermosiphon effect is pushing the coolant anyway, so it's how most cooling systems work. (There are reverse-flow oddballs out there, notably the GM LT1, but the VG is not on that list.) This means the VG's thermostat is on the cold side. I don't know why Nissan did this, but it seems to work. There's a flow chart (heh) on LC-6 of the '94 FSM, but this diagram from the '87 is a little easier to understand--at least once you work out that the grey arrows mean something different in the diagram than they do in the flow chart below.

CL-9 in the '95 manual shows the damper. Looking at the diagram, it's even simpler than I had assumed it was! I thought it was supposed to slow engagement if you pop the clutch, but it looks like it's just adding a little squish to the system. NVH thing? Probably unrelated to this issue, unless it's gone all to pieces inside and the debris was blocking the line back to the master. Now that I'm thinking about it, I've heard of rubber brake hoses failing like a check valve, so you can apply the brake, but it won't release. I haven't heard of a clutch hose doing that, but it sure does sound like what yours was doing. Ackshually the manual calls it an "Operating Cylinder," but, yeah, nobody else does. I've only ever seen/heard it called a slave cylinder.

New one on me. My first thought is heat soak (exhaust leak cooking the clutch hydraulics?) but I would expect that to prevent disengaging the clutch, not make it slip. Does yours still have the clutch damper? I've heard of those acting up. Haven't had to mess with one, given mine's got the slushbox.

A friend and I hole-sawed his S10 Blazer's firewall to get to a bellhousing bolt. Then we did it again, a few inches over, because that's where the bolt actually was. Not our finest moment. (Or Chevy's finest moment, either, but that's the S10 for you.) If you do go for the hole saw, make sure you measure better than we did. Also make sure the hole saw and/or pilot drill aren't going to take out the harness when they break through. I've got a trans with this sensor in the corner, waiting to go into my '93. I think I just found something else to check before I install it!