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Jim2 Jim2 is offline
7.0:1 > 11.3:1
Join Date: Oct 2003
Location: Calgary
Posts: 2,038
The hotter the cam profile results in less idle vacuum observed.

Due to your intake manifold acting as a plenum it's unlikely you will be able to identify a vacuum leak unless you spray around all joints to see if your idle speed changes.

ecu doesn't know the difference between air coming in via a vacuum leak, or going past the butterfly as intended since the air is metered by MAP sensor and crank rpm, CIS by comparison meters the air at the filter and downstream leaks upset the fuel calibration.

Slight wandering vacuum is no issue, especially under warm up. Also, when the engine is cold you will see less vacuum since the throttle needs to be cracked open wider to make up for friction loss due to cold oil. As you refine your engine temp values you'll see less vacuum fluctuation but I wouldn't expect to get it dead steady.
Old 12-28-2014, 02:11 PM
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