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Several possibilities here.
Strongly recommend you get a Nissan service manual - it will tell you exactly how to test different items to ensure where the problem is.
I'd start first with your air regulator. I've been told they only are goood for about 80,000 miles before they start going bad. If it sticks in the closed position you have trouble starting the car cold, runs rich and idles very rough. If it sticks in the open the car starts fine but runs very lean after it warms up. It'll cost you about $100 from Nissan for a new one. Mine stuck closed. I'm putting a new one on this weekend.
The thermotime switch and engine temperature sensor are probably not your problem here as they are more likely to cause your engine to run rich.
You might check your fuel pressure too. It should maintain about 36 psi. If its bad, I'd cahnge the pressure regulator first and then go for the fuel pump.
Anyone else with some ideas here?
Good luck.
Phantom
 

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There is a device called an air regulator. It sits on top of the intake manifold real close to the cold start injector. It is after the AFM. It sits on a plate that has radiator water running through it so it knows when the engine has heated up and has about a 1 diameter hose running to and from it so it can bypass extra air into the intake when the injectors are firing rich during cold start-up. It's a funky looking thing. You can find a picture of it in the Haynes manual or, if you've spent the money, the Nissan Service Manual. Trust me. If you have a 75-78 280Z you're supposed to have one of these things.

> I'm a little confused by Phantom's request
> for replacing the air regulator. Does he
> mean the air flow meter (AFM) or air temp.
> sensor in the AFM? I'm experiencing similar
> symptoms and after reading my manuals and
> having done similar things to my car as you,
> I suspect that I may have some fuel
> injectors that are not working. I installed
> an entire new set of reconditioned injectors
> and based on the noise from the screwdriver,
> I think at least two are either stuck open
> or shut? I plan to start my car and pull
> each electrical connector one at a time
> while my car is idling to see if that is
> what is causing my problems. Good luck.
 

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> Phantom:

> Can you describe the best way to clean the
> bullet connectors, i.e., Q-tip w/ alcohol?
> I've cleaned by other connections, but the
> bullets seem hard to do with a file, etc.
> Thanks.

There are two ways.
1) Go to auto parts store and get a can of electrical contacts cleaner spray, spray them well with it and then work the two halves in and out of each other several times - respray and repeat the process a couple times.
2) Go to auto parts store and buy some new connectors. Cut the old ones off & replace them. I did this as well as replace the entire pigtail and connector that goes to the engine temperature sensor and thermotime switch. They were in bad shape so did a total renewal.
Phantom.
 
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