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Old 09-17-2010, 10:11 PM   #40 (permalink)
Basjoos Wannabe
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Join Date: Apr 2009
Location: Arkansas
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The Van - '97 Mercury Villager gs
90 day: 19.8 mpg (US)

Lyle the Kindly Viking - '99 Volvo V70
90 day: 25.82 mpg (US)
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with half the cylinders dectivated on my 4 L v6 the idle did kick up a bit for certain.

I would plan on making deactivating half the cylinders an objective that can be activated or deactivcated in the cabin. Honestly, you need all 4 clylinders for take off and acceleration, but for cruising you only need to maintain speed, which on the flat land requires only cutting throught the air. According to my scanguage cruising only requires less than 50 hp of the possible 200 hp of the engine. This played out when I would deactivate half the cylinders once I got to speed in my explorer. SUre it worked, but if I had been a bit more ingenious with making the ecu "see" only half the o2 content present it would have worked absolutely awesome.

To make the ecu see only the relevant data concerning the activated cylinders had a plumbing or electrical solution. The ECU depends on the 02 sensor to detect the oxygen content in the exhaust stream. If you make the ecu detect only half the signal of the 02 when in cylinder deactivation mode, it won't "know" you have 2 cylinders deactivated. If the ecu only detects the o2 content of half the cylinders from the o2 sensor when in 2 cylinder mode, it will not "know" 2 cylinders are deactivated and the 2 running cylinders will be running at normal efficiency. Sure you will lose a bit of fuel moving the worthless cylinders (although it would help cool the engine) but you will be using less fuel per rpm.
RIP Maxima 1997-2012

Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
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