Slartibartfast

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!

There are two temp sensors. The one for the dash is one-wire. The one for the computer has two. If the plug for the two-wire is damaged, that could well explain why it's running rich. If it's not the sensor, and it really is struggling to come up to temp, that suggests a stuck or missing thermostat, which could also explain it running rich. If you're looking for the plug for the one-wire, I would try a few sizes of spade terminal and see which one fits. I suspect the stock plug is just a spade terminal with a fancy plastic case on it.

Not immediately ringing bells, but I'll have a poke at the manual. What are the wire colors for that plug? Should help narrow it down.

Sounds like the last guy had no idea what he was doing! Lucky the valves didn't get et. You'd need the spark timing to be pretty far off to get misfire codes, but you could still be losing performance if it's off. Spec is 15 degrees BTDC plus or minus 2, at warm idle. (If you set it cold, it'll be off once it warms up.)

These aren't great on gas, but it should be getting better than 11.5 on the highway. I would check the timing (instructions are in the service manual, free download from nicoclub) and see if it's got any stored codes. Check/clean the MAF, check for vacuum leaks. Maybe throw some injector cleaner in the tank on the off chance it does something. Good thinking doing the timing belt right off. I did the same when I got mine. I also changed the fluid in the transfer case and the transmission, and added an aux cooler and external filter to the trans cooler lines in hopes of keeping the slushbox alive (so far so good). Who knows what maintenance a $300 truck has/hasn't seen over the years. I haven't heard much about the K&N filters that makes me want one. If you do get one, be careful with how much you oil it. I've heard of the oil fouling MAF sensors.

I remember someone ages ago punched a couple of holes in a Nalgene bottle and ran that for a washer res. Might be below the standards of this build, though I knew shocks could get complicated, didn't know the springs did too! I would not have expected the order of the springs to matter.

Trailmaster used to make a 4" kit that dropped the whole front suspension down, like a subframe drop for a unibody truck, but that's long since out of production. Otherwise, no, you're not gonna get more than 3" out of the IFS. Body lifts are still available, though. I remember a few people here running 3+3 and 33s (3" suspension, 3" body, 33" tires) back when I joined. Beyond that, yeah, you're looking at hardcore custom fab.

Looks like the OE part number is 472101W700. If you can find the original listing, it may list what it fits.

Is yours round-dash or square-dash? If it's square, get the '90 manual off cardiagn.com. Round, use the '94/'95 from Nico.

Here's a guide to manual-swapping a '96-'99 truck. (Not mine, all credit goes to Keith Maddox.) Not sure if the guide talks about the oil or not, but in case it doesn't, you want GL-4, not GL-5. AFAIK the VG33-powered R50 got the same manual trans as the VG33 W/D22 (first-gen Frontier and Xterra). The W/D21 trans should also work, but Nissan did a dumb with the oil level in the early ones, so if you have the option, I'd look for a '96+ donor. VQ35/manual R50s do exist, but as Hawairish said, they are quite rare. Good luck finding parts. There was a guy on here a while back having a hell of a time finding a flywheel for one. Either way, I would look for a manual R50 with the same engine and something wrong with it. Part yours out to fix it, or part it out to swap yours. Saves you finding all the pieces separately.

Sadly Nissan did not put a Shrader valve on the rail. The service manual says to plumb a pressure gauge in between the filter and the rail. You want around 34 psi with the engine idling and the vacuum line to the regulator hooked up, and around 43 with the vac line off. (If there's fuel in that vacuum line, then the regulator's toast.) You'll spray fuel from hell to breakfast if you open the lines while they're pressurized. The manual says to pull the fuel pump fuse, start the engine, wait for it to die, and then crank it a few more times to be sure. This may be difficult given how yours doesn't really run. Worst case, let it sit overnight to hopefully bleed the pressure down, and then separate the lines with a rag wrapped around the bit you're separating in case it's still pressurized. Both procedures and specs are on EC-37 of the 2000 service manual, free download from Nicoclub. I'm guessing the truck sat for a bit after the belt failed, given the dead fuel pump. How bad did the old fuel smell? Hopefully it hasn't gummed something else up. I would be surprised if the fuel filter was bad enough to cause a no-start, but I would still throw one of those at it while I was in there. Pull a spark plug after it runs/dies. If it's wet, then you know it's getting fuel. If it's getting fuel, my next guess is timing. Did you mess with the distributor? Do you know that the last guy didn't? I would try adjusting the timing around and see if that changed anything. (If you don't think it's been messed with, mark it first so you can put it back where it was if you don't get anywhere.) If the distributor has been out, it could also be a tooth off. I doubt the knock sensor code is related.

Does sound like the motor's on its way out, but you might get a little more life out of it by making its job easier. Roll the window all the way down and lube up the channels that the window slides in with silicone spray. Use the straw to get it down in there. Try not to get it on the rest of the window. Spray some of the same on a paper towel and wipe it into that bottom seal that's catching. I would also clean the glass, on the off chance there's something on the glass that's helping it catch on the seal. You want the spray that dries. The dry stuff doesn't pick up dirt the way wet lubes do.

I'm not sure what would cause that other than junk parts, assuming the plugs and boots are OK and the plug wells aren't full of oil. I'm assuming the mechanic swapped them around to confirm that the coil pack was the problem, and it wasn't the same cylinder each time. Were the old plugs oil-fouled/unusually worn/tested bad, or were they replaced as a "while we're in here?" I'd be surprised the valve covers leaked enough to lose that much oil. There's an oil cooler that also tends to leak. Unfortunately the early VQs also tend to burn oil. My dad's '03 burned a quart/1k miles. Ran fine, but smoked out the parking lot on a warm start. (We suspected valve stem seals, but never tore it down to find out.) I don't remember it having coil issues, though. Looks like you can still get OE coils from Nissan. They ain't cheap, though.

The '04 service manual (free download from Nicoclub) says P0183 means the computer is seeing a higher-than-expected voltage from the tank temp sensor circuit. EC-293 describes the code and says what the voltage should be. Looks like one side of the sensor goes to the cluster, and the other goes to the computer, so if you've only buzzed out the wiring to the cluster, looks like you have another one to chase. There's a diagnostic procedure starting on EC-296. Run through that and see if you get anywhere. I would also unplug the sensor and pump and make sure there's no continuity between the sensor and any other connection on the level sensor or the fuel pump, on the off chance something is crossed up internally. I don't know if this is even possible (looks like the connectors are separate and the sensor is a sealed unit), but it would be pretty quick to rule out.

Sounds like a wheel balance issue to me. If this started suddenly, after driving in mud or deep snow, check that the back side of the rim is clear. A big wad of something stuck back there will make it shake like hell. If you suspect the tires, visually inspect them (make sure they're round, no weird bulges), and if they are, rotate them (fronts to the rear, rears to the front). If it clears up, one of the wheels that was on the front may have thrown a weight. You could rotate one side at a time to work out which wheel has the problem. I would expect a dragging brake to cause a pull, not a wobble. If the wobble is the same whether you're on the brakes or not, I would not assume it's related. That said, probably best to get the brakes working properly before chasing the wobble at highway speed. While you're under there, check for anything obviously loose up front. Wheel bearings, control arm bushings, tie rods, ball joints, rack bushings, strut tops.

Check the center console by the E brake. If there's a switch with a red LED that says something about sensitivity or mode or whatever, that's for the alarm. Also look in the engine bay, inner fender on the driver's side. Should be a black megaphone looking deal if it's got the alarm. I don't know that they were standard equipment, but they certainly weren't rare. The hot wire should be easy enough, though the starter is a bit of a pain to get to. The starter motor has one big wire (to the battery) and one little wire for the solenoid. Attach a wire to the solenoid in place of the standard wiring (don't remember if it plugs in or bolts on), hook that to battery +, and if the starter is good, that'll make it go. Unhook the battery first! It's easy to arc a wrench between ground and the positive battery cable.

Score! I wondered if the Jeep disco setup was what you were hinting about in the last post.