Toiletduck34

to be honest i havent even looked at the exhaust. Im assuming it does have cats. I did have a 10K potensiometer laying around and tested this hack from siteunseen and it did work when setting the ohms to ~1000. Car reved to 4500-5000 before shifting without any hesitations. im not planning on driving aggressive at all. but just trying to get the car running well.

searching for a potentiometer is not so easy now adays. i miss radio shack.

Thank you for that info, ill see what i can get done. i would like to see if this would be a main cause and a fix verse a bandage. In the long run im doing to be redoing most of this with more modern technology so it might be a moot point.

I've been getting a 1977 280z up and running after ~20 years sitting. I've replaced all fuel lines, pump, tested for vacuum leaks, etc. I feel like ive tried to tune this thing with the AFM, TPS, and idle screw. If finally have it idling around 800-900 rpms and good power up to ~3000 - 3200 rpms then it feels like it loses engery and sounds like an airy fart. sorry but i dont know how to explain the feeling/sound. it doesnt sound like its about to die b/c its at higher RPM but it feels like it loses all get it up and go. it tried to increase RPM but does very slowly. this is very apparent on 1st and 2nd gear. When i shift into 3rd and 4th i am going fast enough im dont want to floor it. What should i be adjusting? ***side note*** when not in gear I can rev the engine 4-5000+ RPMs and it revs beautifully without hesistations. only when under load.

So i got everything working. I found an issue, i dont know if this was from facotry or the previous owner changed the wiring harness for the headlights but the black/red wire for ground was wired to the center post for the headlights instead of the larger white/red which is how the 1977 wiring diagram shows. I changed everything and put new lights in and it works. However i need new connections because many of the connectors are completely broken and fragile.

Thank you for that information. Yes last night i opened it up and found one of the spring contacts was missing entirely and the other one was severely bent. I attempted to create my own but was unsuccessful. Im going to take it apart again today to see if i can repair.

I've done more research and grounded one of my headlights and that works. I've now moved on to the rear running lights which are not turning on with the headlights. I am getting no 12V send to just the running lights. the breaks, reverse, and turn signals all work fine. looks like im not getting any 12v to the green/yellow. I tried following to C10 but no luck at this point. Im trying to open each connection to clean them but they are extremely stuck.

I am going through my project car and trying to track down why the headlights arent working. The headlights and running lights are not working. Testing the connections i am seeing the the ground has power. While tracing the wiring back and testing the combination switch behind the steering and the hi/low switch crumbled to bits and broke. I am going through the 1977 wiring diagram and trying to understand what goes where but i cant find the short and its useless. can i get a good wiring harness or partial harness?

Thank you for that information that's great. I personally like the body lines but if done well it looks great. This one was done in the '80s and I'm sure it looked great then but it's had a hard life since.

im working on my 280z project car and tackling lighting currently. I went to remove and check the wiring for the headlights and one of the previous owners in the 80s decided to WELD the buckets to the fender... He did alot of body work to make the car have very minimal body panel lines and used bondo to smooth everything out. i thought that was just it until i took it off and its stich wedled... poorly at that. ill get them off but not right now. Can i replace without removing the bucket?

ITS ALIVE. i decided to take off every electrical connection off and deep clean each pin. they didnt have bad corrosion but the copper had turned green where it wasnt connected for the last 20 years. I double checked each pin ohms coming through the ECU and finally got each reading within spec. Started it up and boom perfect idle. I appreciate all you're guys help. the resources and information helped a ton. now to bleed the clutch, find out why the break pedel is stuck and see if this thing can move!

I can't give up... So troubleshooting I eliminated the air idle valve for a moment because it felt like it was choking the engine too much and it not idles but rough. I also think the connection is bad with the TPS. In the attached video I am trying to make the connection solid and it starts to idle down. PXL_20250916_015703945.mp4

I think im chasing my tail on this one.... This morning i repalced a few fuel lines as 5-6 started to leak and crack from the fuel pressure. I also used some electrical cleaner to clean all the electral connectors. I started to engine and it can now run past 10 seconds without fail. not sure why. but great! the issue now is its running very poor. Rich and extremely low idle. I tried adjusting the AFM and idle adjustor but nothing is effecting it. I double checked the ECU connections and now im not seeing any ohm readings on the appropiate pins for the AFM and the TPS. I checked the TPS internals and connectivity is all there. it must be the wiring somewhere. In the end i wanted to get the engine running and it is! so thats fantastic. I think im done troubleshooting this thing and im just going to leave it as is for the moment. I plan on replacing this entire ECU/AFM & fuel system anyways with megasquirt or similar system. No need to fix this system if im going to be getting rid of it. Now its time to tear things thing down to the frame.

That makes sense, I already testedt all the ECU pins and were reading correctly... The only thing left is the AFM which would also make sense why the injectors wouldnt firing. I tested each injector and they are functioning. I have stopped testing for the night because i broke a fuel line that was very old. will need to replace that before messing with the AFM. but i dont think im getting good signal from the AFM to the ecu. thank you for your help everyone.

I am reading through the FSM and all the materials trying to track down what i can find. Using AI is extremely helpfull as it walkthrough alot of troubleshooting and ruling things out. Right now i believe ive rules out the fuel system, the injectors are all functioning and sensors because its stopping after a running for ~9 seconds regardless of its tempature, hot or cold. The last thing for the ECU troubleshooting is the Tachometer. I am getting a signal from the coil at the tach, but i dont know if the ECU is getting that signal. That would explain after the ignition start sequence it doesnt see any RPM and doesnt tell the injectors to fire causing the engine to stop quickly every time. I am trying to find a pin that the ECU would recieve this information but cant find one.

I'm reading through some stuff and looking at information the AI and it brough up the thermotime switch. it functions at start up for exactly the amount of time my engine stays working.

1980 EFI Bible.pdf

sorry im refeering to the cold start valve. I thought i wasnt getting enough fuel after the initial start and checked the fuel pump and its sending fuel, the filter is staying full. there has to be something that stops sending a signal of some sort after the start procedure because I ran a test. Test: started the car and let it run for 8-9 seconds. the moment i hear it start to fail i click over the egnition for just a moment. the starter grinds for a milisecond... BUT the engine continues to run. I did this 4-5 times to let it run for ~1 minute and it idle perfectly. ****maybe im only getting gasoline from the cold start valve... when it stops im not getting anything from the 6 injectors.****

i added a new fuel filter a few days ago. I ran the old fuel out with the pump and added about 5 new gallons, ran that through until it cleared out. it should be good enough to keep it running. Im leaning towards now the cold start sensor and the thermal switches. still trying to understand all these system. these sensors are ~50 years old, im sure they arent working perfectly. I think im to the point i know the engine is good. i want to tear this entire engine bay apart, clean, replace and start from fresh.

its not near close enough to get into the intake. I did test the injectors and they are coming up with 12V now. When i tested them i was testing while cranking thinking both sides would be (+, -) but both sides are showing 12v. i can make it leak anywhere on the fuel rail and it seems to work. its really odd. i dont know how the fuel pressure regulator works but maybe i have too much pressure? Ill check the RPMs. EDIT: RPMs shows, i can keep revs around 800-1000+ and it runs for 10 seconds then stops every time. I engine has warmed up and I tighened the all the hope clamps so gas isnt leaking out and it still runs. Maybe whatever cobwebs were cleaned out since its been sitting for 10+ years. will continue to read and troublshoot.

UPDATE: Thank you for that information. I have unplugged everything I could from the Neutronics device, though I'm not sure if it's affecting anything. However, I've made a big step forward: I can now get the engine running for a short period of time! I don't understand why, but hopefully it makes sense to someone here. Here's what happened: I decided to clean the cold start sensor. While I was putting it back on, a neighbor came over to talk, and I forgot to tighten the hose clamp that connects to the fuel rail. I started the car, and it ran—but with a fuel leak. If I tighten the clamp back down, it won't start at all. I checked the fuel return line to ensure it's flowing, and it's fine. When the engine does run, the RPM is very low. If I increase the throttle to approximately 1500-2000 RPM, it runs perfectly for about 9-10 seconds and then instantly dies. This happens every time without fail.

I tested the voltage going to the injectors and I'm getting right around one volt or less.

As advised by Zed head, I'm going to start my own thread to document everything I've troubleshooted while trying to get this car started. This is my first EFI car, and I'm learning as I go, but I believe I've narrowed the problem down to the EFI system. The fuel pump is running and generating good pressure within the fuel rail. I have found no leaks or vacuum leaks. The AFM (Air Flow Meter) appears to be working; I can see it moving while cranking. I checked the continuity at the ECU pins, and the readings are correct, one pin is slightly higher resistance but looks to be okay. Im not sure if the AFM has a connection that i can take off an clean. looks to be directly wired. The starter/injector relay on the driver's side is clicking over and functioning properly. I've installed a new ignition coil and verified that there is spark at the spark plugs. The car can start with starter fluid but will not continue to run without it. Beyond this, I am unsure how to check why the injectors aren't getting a signal. I'd like to avoid removing the injectors and disturbing the fuel rail for now. My main question is how to troubleshoot why either the injector relay or the ECU is not sending a signal to the resistors, which in turn should activate the injectors.

I live in arizona... i bought it and it just arived in less than 24 hrs. fastest turn around for a relay i thought i would have to wait 1-2 months for.

I just picked up a 1977 280z with a wiring harness for a "Neutronics" system. It looks like it connects to the o2 sensor on the exhaust and possibly the ignition coil. I cant find a single google search about this system or a wiring diagram. I have a black, red and green wire disconnected. Any help would be greatful. If more infomration is needed this is a EFI car. I am trying to get it started. can get it cranking but thats about it.