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78 280z RPMS wont go down

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So I just bought my first Z, the engine runs strong for the most part, but something I noticed is when at ~2000 RPMs and you let off the gas, it holds steady.. but if you are at 3k+ it will go down. Also when I first start the car the it idles at about ~900 but after driving it wont idle below 1500.. Not sure if thats a problem or how its supposed to be.



Few other problems with it off the top of my head if you have any ideas:

Right blinker lights solid if you brake.

Wipers dont work, dont know where the motors is if you can point me in the right direction.

I have a screeching sound in the engine after hitting a curb at about 25.. alternator belt maybe?




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Do some research about the B.C.D.D. I believe that is what it is called. Its the piece on the bottom of your throttle body. The wiper motor is located under the cowl panel, which is the panel between the hood and windshield. Your wiper motor is most likely a bit corroded and needs to be cleaned up. What happens is there are two drain holes under the cowl panel they can get clogged up with leaves and dirt then water collects and leaves the wiper motor submerged partially leading to corrosion. I don't really have any advice on your "screeching sound" I suggest you do some more observing to figure out what it is. Also concerning your lights I suggest you clean up your hazard lights switch that tends to corrode sometimes also check your light switch and the connections.

Edited by 19752802+2
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Yowsa... if you don't know where the throttle body is... you should ask yourself if you have the skills to fix the problem. This BCDD will involve taking part of your intake tract apart to fix it. The high idle thing isn't something new to 280z owners. Some searching on this forum will do you some good before you get flamed by the moderators. It has been covered lots of times.


In the FAQ section of the forum you'll find service procedures and factory manuals:





Also do a search for the fuel injection book for the 280z. I have a local copy on my harddrive if you can't find it on this site.

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  • 1 month later...

About the high idle there is a dashpot bolted to the throttle body. Its a white circle that looks like there should be a hose connected to it. Well there isn't supposed to be a hose. Anyway on the bottom of the dashpot there is a spring loaded rod that moves in and out of the dashpot. That rod presses on the throttle. Sometimes it gets stuck. It can be adjusted you should look in the Factory Service Manual to see how. I actually removed it. There is also an idle control for the A/C. The idle control is at about the half way point along the throttle linkage mounted to the intake manifold. Follow the Throttle linkage back from the dashpot to a spot where its straight then has a little bend and goes straight again. At the bend is where the A/C idle control is. The idle control has a vacumm hose connected to it with a hook comeing out the other side. That hook pulls on the bend on the throttle linkage when vacuum is applied. That raises the idle about 200rpm when you turn on the A/C. If you don't understand what I have said then don't mess with anything and take it to someone who can help you.

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