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Old 01-30-2013, 09:47 PM   #9 (permalink)
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Join Date: Jul 2012
Location: camden, MI
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MC SBX - '95 Chevrolet Monte Carlo LS
Last 3: 29.75 mpg (US)
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you know what the fastest way to make the ECM angry is? having the O2 sensor signal drop to full lean when it expects it near stoich.

when you cut fuel, you should probably simulate a normal O2 voltage, otherwise, the ECM will add a bunch of fuel into the short term fuel trim until one of two things happen:

it hits its limit and sets an O2 error code


the engine comes back on, runs rich temporarily until the ECM takes back out all of the extra fuel it commanded during the DFCO event

of course, if going into DFCO while in open loop, neither of these things will happen. in any situation, do yourself a favor and have the DFCO event also start generating a false O2 sensor signal, otherwise you'll probably end up using more fuel than without it. if you do see gains, they won't be as high as they could be.
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