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Author Topic: Cylinder deactivation  (Read 5393 times)
jibberjive
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« on: December 19, 2012, 01:21:18 PM »

Just kinda throwing this out there for discussion because I was thinking it would be cool if possible.  I haven't looked in detail yet at what exactly the OEM's are doing when they do the cylinder deactivation for increased fuel economy when cruising on the highway. Spark and fuel cut on the deactivated cylinders is obvious, but ME7 only has control over the injection time by banks (ti_b1 and ti_b2), not by cylinder, correct?  If that's right, then I guess the idea is shot down right there, not to even mention the difficulty to deal with the desired load/torque, maf readings, etc.

Anywho, just thought I'd spark the conversation.
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elRey
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« Reply #1 on: December 19, 2012, 02:03:08 PM »

Without the ability to deactivate valves also, how would you account for the leaner mixture due to fresh air flowing thru deactivated cylinders?
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jibberjive
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« Reply #2 on: December 19, 2012, 02:45:07 PM »

Yeah, I was thinking about that. Not sure on a narrowband car, but on a wideband car maybe just halve the desired lambda to account for the 2x as much air?  Not sure.
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prj
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« Reply #3 on: December 19, 2012, 02:48:18 PM »

Yeah, I was thinking about that. Not sure on a narrowband car, but on a wideband car maybe just halve the desired lambda to account for the 2x as much air?  Not sure.

There was a thread about this recently.
Unless you can keep the valves of the cylinders in question permanently closed, forget it.
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phila_dot
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« Reply #4 on: December 19, 2012, 03:24:17 PM »

What they said.

Just FYI, there is cylinder specific injection control.
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userpike
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« Reply #5 on: December 30, 2012, 10:26:30 AM »

Unless you can keep the valves of the cylinders in question permanently closed, forget it.

yep, GM started this in 2005 with some of their v-8s. oil pressure deactivates the lifter and allows the push rod to telescopt into it, as the lifter rides over the cam lobe, keeping the valves from opening.
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