I am seeing a number of engines with V configuration (V6 and V8) that present only a fraction (mostly 1/2) the number of peaks in a 720 degree cycle as there are cylinders. The ones that are 'easy' to postulate a reason have a Cylinder Deactivation (CD) technology feature: AFM or DFM for GM, MDS for Chrysler, ACC for Mercedes-Benz, VCM for Honda and CD for the Ford EcoBoost I3.
But the 3.5L Toyota Venza and Ford EcoBoost V6 seem to have manifold designs that combine the exhausts from the different banks with phase shifts so that they combine as pulses with higher pressure but lower frequency.
Do other people see these at 1500 rpm and higher with no load?
Other hypotheses to check out?
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- Waveforms with fewer pulses than cylinders.docx
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