NewZed

Have you tested the sensors that tell the ECU how much fuel to add?

He did a great job as a moderator here. He seemed like a really good guy. Looks like he was active on the site just recently, so it must have been sudden.

Some is normal. The retaining circlip has some play in both grooves. People have been known to lose the circlip or just not be aware that there's supposed to be one in there, and run with a loose axle. Take the nuts off and see if the axle is retained. You're sill misguided on your lug nut issue. Any play in the lug nut or stud area is bad. Any. There's no close enough. The wheel should be firmly attached to the flange, as if they were one piece. That's a basic of any wheeled vehicle, no fuzzy area to think about.

No problem. And I'm not your bud.

The loose lug nut thing is a big concern. How can you drive around with loose lug nuts and not know it? They were so loose you could feel the play be shaking the wheel by hand? That's a lot of loose. And there shouldn't be an "as much as I could" in there. There's either a torque value or you know from experience. Are you running steel wheels or mag wheels? There are many ways to have a bad wheel. Bent steel, or wallowed out aluminum on the mag, or lug nuts that are too long and bottoming out on. If you've identified a wheel problem, swapping to known good wheels for a test would save you a lot of time. You should spend more time on the wheels and make sure that they're right. I used a vise to press my bushings out, and only heated the metal behind the rubber to destroy the bond. Burning the whole thing is neat-o but really just makes a lot of unnecessary mess.

The easiest, closest thing to a bolt-in, option might be one of these - https://whiteheadperformance.com/performance-parts/datsun-240z-260z-280z-1970-78/240z-280z-diff-differential-axles-lsd/ They are hard to find on the open market, the CL's and eBay's don't have many. You can also get an open R200 and convert it to LSD with one of these - https://www.whiteheadperformance.com/?s=differential&post_type=product Neither of these are bolt-in because you'll need a different mustache bar, and modified propeller (aka drive) shaft. If you try to run all of that torque through an open R180 diff you'll probably just break it right away or it will wear out from spinning one wheel.

Here you can see that there's only 1.58" of travel combined in the two joints. Could be that your problem isn't too little travel, but too much, on the inner joint. 2 x "not much at all" = correct.

Your question has already been addressed then, you just need to use the answer in your response. Seems like you might be looking at your axle backwards. And 2 inches of travel in either direction would be 4 inches of total travel. I don't think that's possible.

You haven't really defined a problem, besides "very little", which, somewhat ironically, means very little. Also ironic, you need to be more articulate in your description. Seriously. It's not clear what the problem is.

You say unbalanced but you describe loose. Sounds more like a bad bearing or bad suspension bushings.

I didn't post earlier because you said that you were taking it to a transmission shop, but you might compare 3rd gear to 4th gear. 4th is powered straight through the transmission. while 3rd uses the countershaft. If you have a bad countershaft bearing you won't notice it as much when in 4th under power. You might also drain the fluid and check the drain plug magnet. Not uncommon to find bearing retainer pieces on the magnet. The adapter plate bearings go bad. Just noticed that you said 3rd or higher. There are also main shaft bearings in the adapter plate. The two in the front cover go bad also. Either way, draining and checking the plug will tell you something. Easy to do. Remove the fill plug first, to be sure that you'll be able to refill it.

I would focus on the quality of the signal on the blue wire to Pin #1 at the ECU. I've described my experience with the missing tachometer before and people have said it's not true, there's no rational reason for it, and they've also shown that their engine would start without it. And mine will even start without it now that I've switched to a different ignition module. But when my car was factory stock it would not start if the tachometer was not connected to the branched blue wire circuit. There was something about the balance of those three things on that circuit, the ECU, the tachometer, and the ignition module. I had it happen twice, once with a 78 parts car and twice with my 76 car. I even confirmed it by removing the resistor in the line to the tachometer, on purpose, to see what would happen. It wouldn't start at all, not even a pop. So, is your tachometer intact and does it work would be my next question. You've shown that you have everything else that you need, and the fact that it runs once it starts shows that everything is there. You're in the "bizarre causes" regime now. You might even swap tachometers or plug in another if you can get to the plug. Or swap ignition modules if you have another, even though yours works. I have solved tachometer problems by adding a condenser to the negative terminal circuit. The signal was noisy. and the condenser cleaned it up. Hook up your noid light to the coil negative terminal and see if it behaves normally or shows some weirdness.

By "crank" signal, you mean Start, right? Pretty sure that is for Start enrichment and won't stop the engine from starting. He has the FMS and the EFI Guide to show this, and he's already run some tests. He just needs to keep track of what's happening, when it happens. Especially now that he knows it's a sporadic problem. The part about the trigger from the coil negative is right. But that's also covered in both of the books he's been using.

You kind of answered your own question. It's not a "signal" to the injectors, it's just completing the path to ground so that current can flow through the injector bodies. Each time the path is completed, the injector opens. Then the circuit is broken and the injector closes. Electricity is very fast, it all happens in milliseconds. You're not reporting all of the numbers that matter. It looks like you have a fuel pressure gauge on the engine but you didn't say what it is when it won't start and what it is when it will. No offense, but you have to be methodical to make progress with the EFI systems. You can't just look at one thing at a time. Many things have to be right at specific times. You need to know that you have power to certain places, pressure in the fuel system, certain signals going where they should go when they should go there, etc. You should have a check list that you run through, either on paper or in your head. Correct power - check (look at your meter), correct pressure - check (look at your gauge) , spark - check (look at the tachometer, it counts sparks)... Forgot to say, I had a 78 parts car that would not start when the tachometer was out. Somehow it screwed up the circuit to the ECU, since it's on a branch of the line from the coil negative terminal. So there are some odd things that can happen when everything else is right. But you need to know that everything else is right before you get in to that.

Those will work. The shifter is the same for 4 and 5 speeds, up to the ZX's.

Edit - forgot to say that people have been known to grind out a hollow for the nose of the diff to get a proper fit. That will raise it some. Enlarge the side holes a bit, do some grinding, a couple of shims on the bar... Just to fill in, I made a picture. 5/16" shorter. They also have one that says V8 only. But it's cheaper. Can't really figure out the page - http://www.energysuspensionparts.com/search.asp?pg=1&stext=3-1108 http://www.energysuspensionparts.com/3.1158

I'm sure it's an unintended consequence but the new software seems to be open for high school trolling. Is it Twitter? Not good. This is some weird BS... http://forums.hybridz.org/profile/55044-conrad280zx/

It's easy to get misled on the injector connectors and voltage readings. When all six are connected, if you remove one measure voltage you'll see it on both pins. Because the injectors are on a parallel circuit. If all of the connectors are disconnected you'll only see it one side because the other 5 parallel circuits are broken. So it sounds like your injectors are getting proper power, which shows that the EFI relay is working correctly. The injectors don't get a "signal" the other side of the connector just gets grounded, allowing current to flow, creating a solenoid magnet, and causing the injectors to open. The grounding is done by the transistors in the ECU. The ECU "tracks" when to open the injectors by "counting" the sparks it sees on Pin #1 at the ECU connector. You want to be sure that Pin #1 is connected to the negative post of the coil. That's the signal that the ECU uses. You started the thread with a weird power problem, now you're in to the EFI system. Sometimes when a bunch of weird things are happening you have to go to a firm starting point and just start measuring things until you find a number that's not right. Here's a link to a really good troubleshooting guide for the EFI systems. Find 1978's procedure and start measuring. Get real numbers, and write them down. some thing will show up. The 1980 EFI Manual. It covers all years of EFI up to 1980. Yours in in there. http://www.xenonzcar.com/s130/other.php

Which relay did you use, 77 or 83? They're different. The test procedure for the relays is shown, with pictures, in the Engine Fuel chapter, or the EFEC chapter. Probably easiest to put a meter on the fuel pump leads and see if there's power when the key is turned to Start. You'll probably see power and can move on to some other possible source. Listen for pump noise. Disconnect the starter solenoid so it will be quiet.

You haven't said what year car you're working with. The relays changed over the years.

Is it a 1982 Ford F150?

Pretty sure he just calls out the wire colors. Here's a few, plus the Google search terms. Might be enough in here. https://www.google.com/search?q=site:hybridz.org+cgsheen+280zx+distibutor+wire&ei=3ebBWbDJNNTIjwO8qak4&start=10&sa=N&biw=1230&bih=881

He hasn't been on for over three years. cgsheen has posted a few times about which wire goes where. Tell people what you're actually working with first though, it's not clear.

That's normal, a long and a short. Although, with the VLSD diffs, the long one is a lot longer. Can't remember the actual measurements. Better check, the parts stores have been known to sell the wrong shafts. 300ZX's came with VLSD's in later years. Edit - just remembered that the VLSD's came with a different spline count also. Count your splines.

Download the 1980 EFI manual and run the tests for 1979. It has tests for all EFI engines up to 1980. This will tell you if all of the critical parts are connected properly. Seems like your coolant temperature sensor might be disconnected. http://www.xenonzcar.com/s130/other.php If you get some parts showing as incorrect, use the FSM to find out where they are and how they should be connected. Engine Fuel chapter. http://www.nicoclub.com/FSM/280z/1979/