Another gas saving question
11-13-2004, 09:43 PM
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Another gas saving question Since cars get better gas mileage at closer to 15.5:1, is it possible to place a resistor in the O2 sensor signal wire to trick the PCM in to running the car leaner? I guess I'd want an average of 50-100 mv increase in the sensor output, so it thought it was a tad rich. To do that I'd need a really high resistance value between the signal and a ground, right?
11-13-2004, 10:34 PM
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I don't believe DC offsets will be meaningful, because it's
switching-mode feedback. You would need to apply a
pulse width distortion. Seems like too much of a project.
I believe however that forcing open loop operation can
let you put it where you want it; just return to closed loop
when you think you need a tune-up; old school. If you have
the open loop tune right the closed loop does nothing
anyway. Sit in open loop and who says your open loop
fuel air table can't have 0.900 for the MAP rows that you
cruise in?
switching-mode feedback. You would need to apply a
pulse width distortion. Seems like too much of a project.
I believe however that forcing open loop operation can
let you put it where you want it; just return to closed loop
when you think you need a tune-up; old school. If you have
the open loop tune right the closed loop does nothing
anyway. Sit in open loop and who says your open loop
fuel air table can't have 0.900 for the MAP rows that you
cruise in?
11-14-2004, 12:07 AM
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The problem is I don't have HP Tuners for this car. I need a cheap way to sort of do the same thing. The O2 sensor works by flipping above and below a midpoint (the average might converge on 600 mv?), so I'd need to find some way to shift that average up. How would I figure out what size resistor to use? It's been awhile since I applied Ohm's law... 