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low and high RPMs


Josh280z

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My 280zx has had fuel issues. I've put in a new fuel pump, a polyurethane tank, new adjustable fuel pressure regulator. Now, it runs great when your going down the road no issues. My problem lies in before and after driving it. When i first start my car, in gear, it idles at about 500. After running it (and it runs fine) I come back, pull it out of gear and idles up too 2000 RPMs. I've had a friend mess with the air/fuel screw on top of the throttle body... I need some help with it.

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You need to let the car warm up, and set the idle while the car is at operating temperature.

 

Then you need to get out your haynes manual or your FSM and read up on the thermovalve that's on top the intake manifold...looks like some kind of pump but it's just a warmup valve. Make sure it's working, or you will have to use your foot to get the car started...which isn't too difficult.

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Thermovalve? I have the FSM, can't find anything about it. I don't think it is that though. I the idle just isn't right. After, I run it hard and it is warmed up it runs 2000 RPMs out of gear. I dont know how to adjust the idle lower, or higher or even how to adjust it downwards.

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adjust the idle with the throttle stop, idle air screw and or proper timing if needed. as said above, adjust idle at proper running temp. then if it wont idle when cold clean/check the thermovalve, or cold start valve or idle air control or whatever that fsm is calling that glorified thermostat ontop of the intake manifold.

 

also check all the vac lines, hoses to and from said valve, pvc hoses, etc. vacuum leaks play a big role in idle problems.

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