What Should The Vacuum Be At Idle. Give us a vacuum reading at an idle. Common causes for this include vacuum leaks and a faulty idle air control (iac) valve.
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Your afr indicates a vacuum leak also. should be bouncing around 14.7afr at idle. That reading should be between 17 and 22 inches of mg (mercury). Idle vacuum for most engines is about 18 to 22 in.
If vacuum doesnt increase at least a couple of inches when you release the throttle. you may be looking at worn rings. cylinders or valves. If your mechanical advance is actually 26 degrees then you should have 6 at an idle.
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The vacuum reading should jump as the throttle closes. then drop back to its normal idle reading. Hg at idle. and the needle should be steady (figure 3.24).
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So. it is idling high. The needle will fluctuate somewhat. due to the cam.
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You always use the tdc mark to set the initial timing. 38 degrees of idle timing at idle is way. way too much. hope this helps get this dialed in for you. dave has suggested this modification to many. with nothing but great results.
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Idle speed for your vehicle should be between 725 and 750 rpm. 2016 gt shadow black premium 6r80. gen3r. jlt 125mm cai. id1050x. dw400. kooks 1 7/8 lt’s.
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Also check the barbed fittings on the intake manifold are not loose. Idle speed for your vehicle should be between 725 and 750 rpm.
Also Check The Barbed Fittings On The Intake Manifold Are Not Loose.
Run the motor up to 3.000rpm and set the timing at 32 degrees. A stock torque converter will not work. Idle speed for your vehicle should be between 725 and 750 rpm.
Start With The Easy Stuff And Check All The Vacuum Line Connections.
The needle will fluctuate somewhat. due to the cam. That reading should be between 17 and 22 inches of mg (mercury). With regards to f/i. is there an unsafe range of vacuum you should be reading at idle?
So. It Is Idling High.
If youre at altitude. these readings. Now again at idle there is very low vacuum but just off of idle it jumped up to 15 inches. 1 inch of mercury by the way is a measurement that is roughly equal to 0.491 psi.
Idle Vacuum What Is Idle Vacuum?
Also. what should the vacuum be at idle? Some engines use the vacuum advance to advance timing at idle. If vacuum is steady at idle but lower than normal. the ignition or valve timing may be retarded.
Then Look At The Hoses For The Isv And Brake Booster.
If the vacuum reading is steady and between 18 and 22 in hg. Now check to see what you have at an idle. • at idle. with the throttle plate nearly closed (figure 3.25a). engine vacuum will be high.