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Old 04-20-2010, 08:32 PM   #21 (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)

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On the turning off of individual cylinders, I wouldn't recommend it without a bit more thought.

On a fuel injection engine, the o2 sensor is designed to tell the ECUr if the engine is running lean. By cutting fuel to some of the cylinders, you are introducing a ton of o2. When that happens, the ECU decides it is running too lean and dumps gas into the cylinders. So much gas goes in that the cylinders walls can get washed, and gas goes into the oil. Why do I know this? I had a setup on my Explorer to shut off half the cylinders. Nice thing about it was it shut off one side of the engine and it was still balanced; ie no vibration. But my oil level slowly rose unexplicably until I figured out it was the excess gas. ( Funny thing was we were able to increase gas mileage 25% using this method.)

Long story short, the engine ended up slowly dying on us and finally quit altogether. I'm planning on trying this again, but instead I'll split the intake and exhaust in 2, or figure out a way to halve the signals coming from the MAP sensor and O2 sensor so that the computer doesn't detect a lean condition.

Anyone here know how to do that?

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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