300zx rough idle

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Posts: 20
Joined: Tue Dec 26, 2017 4:15 pm
Car: 300zx z32

300zx rough idle

Postby Azazel703 » Wed Sep 11, 2019 8:52 pm

I have a 1990 300zx tt that im haveing a lot of problems with at idle aftet the car has wormed up the vacuum jumps between 10 and 14 and when i pump the brakes it sometimes dies or the idle goes down to like 300 to 500 and the vacuum also goes down to 5 to 8. This also happes when i cut the heat or a/c on. Ive tried to adjust the idle but when i pluges in the aac it doesnt change the idle

Posts: 941
Joined: Wed Jul 04, 2007 10:21 am

Re: 300zx rough idle

Postby macgiver » Fri Sep 27, 2019 1:14 am

Find the vacuum line that goes to the Brake Booster , disconnect it where it comes out of the motor's manifold ,
then blockoff the " now opened " manifold fitting - see how they run ?

CAUTION : you'll NOW have No POWER in the brakes , test idle rpm's sitting still , seriously familiarize how much increased brake pedal force is NOW necessary to slow or stop the car , IF should you want to "attempt" to drive. :facepalm:

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