Quote:
Originally Posted by Frank Lee
I haven't accessed data re: pressure changes while motoring dead cylinders. I'd have to think, though, that there was a reason the OEMs all adopted valve shut-off strategies. You are saying that isn't necessary? Then they added cost and complexity where they didn't need to.
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Emissions y0. Even though they can just shut off a bank and ignore oxygen sensor output for the deactivated one, the cat will favor HC compared to NOx at leaner mixtures, so they need to keep the exhaust stream at stoich. I suppose they could use some funky exhaust routing to do this but it's easier just to deactivate valves.