SadZGuy

Yep, O-ring is back and now it runs like a top.

Alright just an update for anyone who wanders into this forum topic with the same problem. There WAS a vacuum leak at the hose connecting to the aux air reg, I still have literally no possible idea how that leak made such a loud whistle, my ears would actually start to ring if I sat too close to the engine for too long. Anyways, I tightened down the hose and the whistle eventually died out. This then allowed me to set the idle with the screw to 700. So now the car runs like an absolute champ, thanks for the help guys.

So I closed the air bypass all the way and it started right up and idled.... So this confirms that it a vacuum leak.(vacuum leak is acting as idle air bypass). After finding this out I started looking around and found an injector O ring laying on the intake manifold. So I started it up and used some starting fluid to spray the injector area and the rpms rose like it was being revved. So I guess this is 100% a vacuum leak but I'm still confused as to why it whistles THAT LOUD, and why my rpms are only at 500 during idle. could it be because the injector vacuum leak is not enough air for a steady idle, therefore giving the effect of having the idle air bypass screwed down too tight?

Currently unable to do those tests right now but I will get to them tomorrow. I'm a little skeptical that it's a vacuum leak because the car idles at 500 rpm and I feel like if it was a vacuum leak the idle would be faster. However, I'm not an expert so I guess the possibility still remains.

Another thing I noticed from the video is that the second the throttle is pushed down then the noise temporarily stops. Is there some kind of whistle coming from the throttle body when the flap is slightly open and then when its fully open the noise goes away because there is no more small gap/whistle?

The engine is totally stock, here's the video without the belt. Trying to get this solved quickly, and I VERY MUCH appreciate your help. https://youtu.be/aS0lwGR5rkY

Hello all, I have a 280z I recently got running but with some problems. Whenever I start the car there is a very loud screeching noise coming from the engine bay. I tried to detect where it is coming from but it is literally so loud that I cant even locate it. Since I cant locate it through means of sound localization I decided to do some other troubleshooting. For starters my alternator and water pump are new so I know its not either of those pulley bearings. (no ac on this car so I only have 1 belt). First I took off the fan clutch even though I didn't suspect it, and the noise still happens. After that I just took off the entire belt and the noise still happens..... Usually these kind of sounds come from the belt or pulleys so I checked every pulley for lateral play or grinding noises but everything was solid. So its definitely nothing attached to the belt or the belt itself. After finding this out I'm led to believe its maybe some sort of vacuum leak. Almost like there is a very large amount of air being squeezed through a very tine hole just like a whistle. That being said I inspected the engine bay for any apparent vacuum leaks but it looked clean. I'm also pretty sure its not a clutch problem as the noise is strong from the engine bay. As you will be able to see in the video, I can rev out of the squeak if I push the throttle enough but then the screech comes back when the engine falls down to idle speed. I'm stuck here and don't have any idea what this is. HELP?!?!? Thanks. P.S. sorry for the vertical footage. https://youtu.be/o9nhWS6Y2Vk

Ok, I'm gonna try this out but I also think my temp sender might be bad as well.

Yep there is coolant and the water pump is new but maybe I got one with a bad bearing? It sounds like the noise is coming from the water pump area.

OK SO.... apparently I didn't have any fuel in the system to begin with because I just put some in and it runs (awfully). HOWEVER, I was having legitimate ecu problems and I specifically remember having fuel in it when I tested the 1st ecu (swapped ECUs to confirm this and the 1st ecu still didn't work on the car nor did it fire the injectors when the coil was grounded). The problem was that I completely forgotten that I had drained the gas tank to rearrange fuel lines somewhere in between ordering the second ECU. So I actually did have a bad ecu at first but now its running with the new ECU and with some gas in it (who would've thought....). Even though its running it only starts with much cranking and wont stay running for long (i also hear squeaking noise, could this be a vacuum leak?) and also there is white-ish smoke coming from the tailpipe. Anyways thanks for the help, probably wouldn't have remembered about the gas if you hadn't told me to check the fuel inlet. I'm gonna continue looking through these forums for help on these new problems since you guys have an invaluable amount of Z knowledge!

You are completely right, I have no idea how I was led to believe it was a bad ECU. I just checked using a noid light and when I try to fire her up the light pulses. So at this point I am thinking it is still fuel related but nothing EFI related, which I am glad to finally hear.

Thanks Zed Head, I ordered a fuel pressure gauge and I will update you with my readings. Also the the fuel rail is connected correctly to the inlet and outlet fuel lines. Until I get the fuel pressure gauge I will continue testing some more and will update if I find anything new. I hope this car starts running soon, I feel like the problem is something very small and easy because I have replaced most of the EFI and fuel related components at this point.

Hello all, a couple months ago I purchased a 1978 280z that had been sitting since 2001. I started by cleaning and coating the inside of the tank, installed a new fuel pump, installed an extra fuel filter near the tank, and replaced the fuel filter in the engine bay. I also have a new fuel relay, efi wiring harness, ecu, and a new 3 terminal dropping resistor (the 5 terminal and new 3 terminal resistors tested good with a multi meter). I also replaced the spark plugs, spark plug wires, and the pickup wire from the coil to the ditributor. When I try to start the car with starting fluid it will run but only when there is starting fluid present. I'm sure this means that I have good spark. So my problem is fuel. When I did the FSM tests with a multimeter at the harness connector every cylinder checked out good. Each cylinder read the battery voltage meaning the dropping resistors and injectors have continuity from the battery and are good. I can also hear the fuel injectors click when I ground them through the negative wire on the coil. I can also hear the relays give a solid click when I turn the key to start. The power line from the battery to the ecu and the revolution trigger signal all read battery voltage as well and all my grounds also tested good. I know I am getting fresh fuel to the fuel rail because when I pulled on the inlet fuel rail line there was a bunch of fuel that squirted out. At first given all the successful tests, I thought I had a bad ecu, however I just tried starting the car with a new working ecu for the second time and it still wont run. I went and read many posts on so many forums and scoured the internet to find a solution to my problem before wasting someones time and posting about it. However, I am stuck here and dont know what to do anymore. Even though I prefer EFI, I'm thinking of just switching to carbs because no matter what I do the damn thing seems to never want to run. I did all my tests and checks but to no avail. And yes the tach is plugged in. Any help? I'm desperate to see this thing running.