Quote:
Originally Posted by Tomguy
What you need to measure is manifold vacuum. It will be different from throttle body vacuum, which is what teeing off the line to the throttle body will give you.
Best places to measure manifold vacuum since it's the same from these places would be to T off the MAP or just pull off the central lock vacuum and use that plugged directly into the vac gauge.
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Tomguy, there is really no RIGHT place to measure the vacuum. Lexani just wanted a survey of what vacuum others see on their cars and did not specify where in the intake system it should be measured. The manifold vacuum would be slightly greater than the vacuum just below the throttle plate. One point controls the vacuum retard and the other is used by the MPS.
At idle speed air flow the difference would the exit loss of the air flowing from the throttle body into the manifold. I would not think this would be very much, but it would be useful if posters specify where they measured it.
I might re-measure mine at both points and see what the difference is at 700rpm.
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Graham
85 300D
,72 350SL, 98 E320, Outback 2.5