Zed Head

Browse through these forums for a little while and you'll get a picture of what you're in for. 280Z EFI is not like 240Z carbs at all. ECU, relays, fuel pump, AFM, injectors all have to work correctly for the engine to run. If the car has sat for a while, you'll probably be in to clutch, brakes and electrical (lights, etc.) also. Just spend a few minutes reading the threads about 280Zs that won't start or stay running. It's fun but it will probably take some time (and money)..

Maybe some are leaving off the reinforcement plate that comes with the Energy Suspension mount? That would raise the diff nose up a small amount.

Coincidentally, just saw this on Hybridz from a guy who had an ECU that wasn't firing the injectors. Said he had his coil wired backwards. Post #72. Also said his fuel pump wouldn't run because he had a bad EFI relay. http://forums.hybridz.org/index.php/topic/91070-moderns30s-1972-datsun-240z/page__pid__904721__st__60#entry904721

Cozye, just noticed your post. The fuel pump only runs when the motor is running (opening the Air Flow Meter flapper valve) or when the key is at Start. When the key is at On, you can make the fuel pump run, on 75, 76 and 77 cars, by opening the AFM flapper, which makes the contact for the fuel pump. Otherwise the fuel pump should not run when the key is at On. This stuff is addictive. Good luck Funky-P (I hope that's like a Married with Children ref or something and not an attribute...).

Darn! I wrote a nice long post and this thing timed out on me. Hit Go Advanced and everything is gone. Any way for the admins to add a little time to that function? Do I set that somewhere? SBlake, I thought about that, and I have read the same, but I have measured mine according to the procedure and the wires going to the injector all measured line voltage (12.6 V). I think that dropping resistors actually drop current. This is what the manual states - "The dropping resistor is provided to drop electric current flowing through the injector and control unit." (Edit - Not sure of my reasoning so removed it. Tests still worth doing) (2nd Edit - My reasoning was wrong. Apparently both voltage and current drop when the injector is fired. Apparently to nine volts. But at zero current flow, voltage measured is line voltage.) Funky-P, my comments are from the 1976 FSM. Your 1977 might have a different pinout but the test is still worth doing. If you have power, then you can focus on why the ECU doesn't fire.

What is the "lamp to injector harness method". A test light in series with an injector? Watching for flashes? I think the injectors should have twelve volts to them at all times. Testing is described on page EF-23. They fire when current flows and activates the solenoid. Current flows when the ECU grounds the circuit. That is my current understanding of how the EFI works. I could be wrong.

Here are a couple of links from Hybridz on the topic. Make sure you read the whole thread in both, there is some misinformation in the beginning posts. [Edit - no offense to JMortensen (one of the posters in the other threads). Apparently there had been some funky information floating around in general at the time (over 7 years ago).] http://forums.hybridz.org/index.php/topic/19920-r200-seals/ http://forums.hybridz.org/index.php/topic/17356-370-lsd/page__p__126272__hl__%2Bpinion+%2Bflange+%2Bcrush__fromsearch__1#entry126272

Clutch and slave cylinders are good novice projects. Your master cylinder and reservoir are in front of the clutch pedal on the other side of the firewall. Picture with arrow attached. Your slave cylinder is bolted to the side of the transmission on the passenger side. If you look down between the battery and the starter (second picture), and back to the transmission you can see it from above. There is a flexible hose attached to it which holds the hydraulic fluid. Brake fluid is the hydraulic fluid used to fill the reservoir. This is an EFI engine so will look different than yours but the parts are in the same general spot on all Zs. Careful with the brake fluid, it will eat your paint if you spill any.

Howdy MEZZZ, I was just searching the site for some feedback on the effects of using urethane inner bushings on the rear control arms (transverse links) and this thread popped up. I've been changing bushings one system at a time and don't know if I want to do the inner bushings or not, since my rubber ones are still in pretty good shape. How did your mod to the R/T mount turn out? How is the gear noise and how is the ride with urethane bushings all around?

12 volts to the coil and the tachometer hooked up? I am not very good with wiring but I think that the tachometer is part of the ignition circuit, the ground from the coil runs through it to the ignition relay (Page BE-33 in the 1976 FSM [i don't have the page in the 1975 manual]). Just a possibility, if you're trying to start the car but you have the insides torn up. I tried to start mine once with the tach out and broke a sweat for about 5 seconds until I remembered reading about it.

The rubber plug is actually pretty deep, about 3/8 to 1/2" I would guess. And mine fits flush so the screw must be in pretty far. I can't see the head of the screw. But my AFM is a rebuilt one from MSA (or wherever they source theirs from) so I don't know if it was ever properly adjusted. Apparently the stock AFMs are factory-adjusted. But I did end up screwing mine in even farther and the engine idles fine, and accelerates smoothly. I have rethought my original comment about no effect anywhere but idle and I think now that there must be some effect just off idle until enough air is flowing to offset it. One more thing to play with...

The other way to richen the mixture at idle but with little effect anywhere else is by the idle air bypass screw (it might be called the lean adjustment screw or something similar) on the AFM. Turn it in to richen, then adjust the idle speed with the throttle body screw. It's behind the rubber plug on the bottom, side of the AFM. I have a 76 and I had to adjust mine to keep the flapper off of the fuel pump contacts. Haven't been emission tested since then so I don't know where it will come in.

There are few people down here in Oregon parting out lots of Zs on Craigslist. Two of them have been doing it for quite a while, and there's a new guy (new to me in my short Z life) down around Albany advertising a whole warehouse full of Z parts (including fuel tanks), and a guy in Colton (east of Woodburn) that says he's parting out 12 Z cars. Just search 280Z on the Portland Craigslist - http://portland.craigslist.org/

Stopping from reverse.

Sorry Sledge, I gave you bad advice, about the tach (although the jumpy tach is odd). I misread your post or got it confused with someone else's or I didn't read the whole thing. My advice was for a car that cranks but won't fire. I missed the comments about it starting then dying. If it ran before and you didn't move the distributor and you're getting spark then it is probably fuel delivery or injector firing issues. Unless you changed something while you were fixing. Did you move any plug wires or take the distributor off or loosen the distributor adjustment screw? Are you trying to start it with everything, all wires, hoses, etc., attached properly? You can't leave stuff off like you could on a carbed engine, then put it back together after it's running. Everything, including the oil filler cap and the dipstick, has to be on the engine, properly attached. If you can, check your fuel pressure. I agree with Idaho, your original description sounds like a fuel delivery problem. Running then slowly dying shows that you might be running out of fuel at the injectors.

Make sure the lifting pad is centered and/or not too big or you'll crush your exhaust pipe.

Where do the other ends of the wires go? Should be easy to see if you have the distributor out. The location on the thermostat housing will tell you which switch or sensor it is. And from the picture you posted, one of the wires looks green.

Slow day, I'll take a shot. The output from the negative side of the coil has to go to the tach and the ECU so the ECU will know how fast the engine is rotating to feed it the proper amount of fuel. Maybe you lost that connection. I have not actually followed it out, but I do know that if you disconnect your tachometer your engine will not start or run. Does your tach work when you try to start the engine?

Ah. You mean the 4th gear vacuum advance switch. Sorry for the misunderstanding. That is an Emissions device that gives vacuum advance only in 4th gear. Kind of a weird thing. I disconnected mine from the switch and ran the hose directly to ported vacuum (basically just connected the two ends at the solenoid switch). If you reconnected the electrical wires and all of the hoses then you will be running with no vacuum advance in gears 1 - 3. If the PO, for whatever reason, had connected your advance hose to a full time vacuum source, and set the timing that way, you will now have retarded timing, since the hose should be on ported vacuum. That would cause your idle to drop. Just a possibility. It might be worth rechecking your timing with a light. It's raining in Portland (where you're at too I see) so I'm spending too much time here. Tell me to stop if I'm overdoing it.

Like I said, your idle sounded like 1200 - 1500 in the video. Sure didn't sound like 800. Doesn't matter I guess. If that's an old video, it might help to make a new "state-of-the problem" video. The point of the balance test isn't "all cylinders are firing" but "all cylinders are producing equal power". Or not. So you have to measure the rpm drop. For example, if you have a cylinder that drops spark every third firing, you might be able to measure its impact. I think that you might be at the point where you've done almost everything and decided that what you've looked at is all good. And you're looking for something that you haven't heard before. It's tough to help the guy that has done that and done that, etc. The miss from your exhaust sounded like a typical misfiring spark plug, for what that's worth. Have you done the "look for sparks in the dark" test? Here is one possibility for the low vacuum reading that might have merit - have you checked the PCV hose itself (the one underneath that connects to the valve) for holes or cracks or leaking junctions? I think that your pressure test of the intake system would miss that, because it would cause the valve to close, blocking off the crankcase. And the other parts of the system run through ported vacuum. Actually, I think that your pressure test only tested the manifold side and not the crankcase portion, so that might be worth double checking. The throttle valve closed off one end and the PCV valve the other. One other way to check for vacuum leaks (although without actually finding it) is to close the idle screw down all the way. The motor should die. If it doesn't, air is getting past the throttle body or leaking in from outside. I did that on my 78 motor and found that the Air Regulator was stuck open (probably not your problem, just an example).

The video and description help a lot. I don't have any ideas right now but did notice two things that seem unusual, compared to the two engines that I have played with the most, my 76 driver and a 78 parts car. The ticking noise seems much too loud to be injectors, it sounds more like a rocker arm or valve noise. My two engines are nowhere near that noisy, I've adjusted the valve lash on both. And your dwell/tach/volts meter showed 600 rpm, but I'm sure that your engine was up around 1200 to 1500 rpm (what did the dash tach show?). Maybe you had the setting on 4 cylinder instead of 6? The noise from the exhaust would be what I would call a "miss". Just for future reference. If you could drop the idle down (way down, to get a bigger effect), then pull the injector plugs off one by one (some people pull the plug wires but the stray sparks can be problematic), you might find the cylinder that is the source of your miss. The rpm should drop about the same amount for each cylinder that is working correctly. RPM won't drop as much for the weak cylinder. I think it is called a"power balance" test by some.

That's a lot of detail, except for the actual problem description. Is there any way you could get a video of the stumble? Does it fall flat when you hit the gas, or does it start coughing, or does it pop and buck, hesitate and go...? Does it do it with no load, or only in gear? 1st, 2nd, third or all? And "lower rpm" could mean 800 to 1000 or 1500 to 2000. Are you talking about just off idle or as you accelerate or cruising at low rpm? You didn't mention your timing either. Just trying to help, it's hard to tell what the problem is.

Here's a very late post to introduce the guy who walked in to the conversation and just started talking... I signed up for this forum over a year ago, just to look at the pictures. I didn't really expect to get involved beyond that but then I found a problem that seemed unique to my model year so thought I would share. Since then, I think that I've become hooked. This is great entertainment. I picked up a stock 1976 280Z in September 09, that did not run but apparently had at least idled about a year before I got it. Now, with information from this site and a few others, it runs and handles fine, doesn't leak (it's not a greenhouse inside), and I drive it almost every day. So far, no tickets or increased insurance rates. I have very low cash flow so I get a lot of parts at the local parts store and try to fix and improve existing parts before replacing. Hence the "Low Budget, High Value" under my screen name. It would be nice to get OE parts and see what the car was really like in 1976 but it's not an option right now. I'm kind of in between Hybridz and here, but with no welder, mill, bandsaw or metal brake. Just tying up loose ends. I know these sites take some work and can be aggravating at times, but I appreciate having them out here, and appreciate the guys with knowledge who keep coming back to share it.

I'm not sure what a "tcvas" is. If you mean TPS, then not hooked up is a bad thing. The TPS does not have any vacuum hoses connected to it. Blocking a vacuum hose hose won't do much. Pulling the hose will let extra air in to the manifold, which should raise idle speed if there is fuel available. On these EFI systems, all of the components are designed to work together. The ECU computer program takes input from all of them and adjusts fuel accordingly. There are only a few things that you can bypass or remove without messing things up. ... from my limited understanding in the short time I've worked on them.

A low idle seems odd. It should be easy to get more air in to the engine, raising the idle speed. What happens if you pull a vacuum line at idle? The idle speed should go up. At idle, the main one that goes to the carbon canister would be a good test. Even the little one that goes to the white vacuum jug should have an effect. Maybe your throttle position switch (TPS) contact is not registering "idle" to the ECU, so you're not getting idle speed fuel enrichment. This might give a low idle due to lack of fuel. The TPS is easy to check with an ohm-meter or test light. This is just a guess.