# Idle Bypass screw question



## khartman2394 (May 20, 2009)

I have read on here about the idle bypass screw, the one on the back of the throttle body. My question is, how is it supposed to be adjusted. I know it is a 7 mm bolt. On my car, 85 Cabby 1.8L, if I bring it out the idle goes up. Is it supposed to be all the way in, tight or do you adjust out some? If it is not supposed to be all the way in how do you tell if you have it adjusted right?







Thanks


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## vdubsir (Dec 8, 2009)

bump, i wanna know the same


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## WackyWabbitRacer (Apr 24, 2001)

*Re: Idle Bypass screw question (khartman2394)*

The air idle screw is adjusted in or out for the desired idle speed of the engine. You can either use your tach or a dwell meter set on the rpm scale to make the adjustment.
Cheers, WWR.


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## khartman2394 (May 20, 2009)

*Re: Idle Bypass screw question (WackyWabbitRacer)*

How is that different from the one that is on top of the throttlebody? Is one better to use than the other? Makes no sense to me to have two things to do the exact same thing







, or am I off base here? Thanks


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## WackyWabbitRacer (Apr 24, 2001)

*Re: Idle Bypass screw question (khartman2394)*


_Quote, originally posted by *khartman2394* »_How is that different from the one that is on top of the throttlebody? 

If you are referring to setscrew at the linkage stop on the top of the throttle body (TB), that setscrew is used to set the closed position of the throttle plates inside the TB.
To adjust the engine's idle speed, turn the air idle screw on the back of the TB.
Cheers, WWR.


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## khartman2394 (May 20, 2009)

*Re: Idle Bypass screw question (WackyWabbitRacer)*

Ok, thanks for the info. I have been using the set screw to adjust the idle. Are the throttle plates supposed to be all the way closed or are they open a tad? Thanks again.


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## WackyWabbitRacer (Apr 24, 2001)

*Re: Idle Bypass screw question (khartman2394)*


_Quote, originally posted by *khartman2394* »_Are the throttle plates supposed to be all the way closed or are they open a tad? 

They should almost be closed.
Cheers, WWR.


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## khartman2394 (May 20, 2009)

*Re: Idle Bypass screw question (WackyWabbitRacer)*

Thanks. It is supposed to be warm today so I will get a chance to check it and set it right.


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