Reduced vacuum is what cam overlap ala 288 cam does. It can also cause drivability clunky running if using stock cast intake manifold and motronic on a motor not built around that sort of cam
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Last edited by digger; 06-15-2016, 06:08 PM.89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Below 2500, if you snap the throttle closed, does vacuum spike, or stay low?
Low would make me think burnt valves...
tnow, sometimes I just mess with people. It's more entertaining that way. george gravesComment
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Thanks digger. It indeed has stock intake manifold and motronic. I didn't notice any vacuum spike in on/off throttle in low rpm.
Anyways I went ahead and replaced throttle body gasket, looped throttle body water heater and tightened couple hoses on intake and vacuum increased to 12 from 8 in idle which seems right given I have an aggressive cam.
It idles much better now as well and clunk has been reduced in on/off throttle.sigpicComment
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