Running without O2 sensor
09-16-2002, 11:02 AM
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Running without O2 sensor
All this talk of octane boosters reminded me of a question I have. Does anyone know how well the engine will run without the O2 sensor? I'm wondering about mixing in some 110 leaded race gas, without the O2 sensor. One of the tracks I go to only has leaded. I don't have a cat and I don't care about emissions.
--Brian Morris
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--Brian Morris
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09-16-2002, 02:30 PM
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maybe Danno or someone else can confirm but I think the O2 sensor stops reading around 2000 rpms and the cars go to straight fuel/ignition maps,,the O2 is mainly for idle and lower rpm.
Did I get that right?
Did I get that right?
09-16-2002, 04:40 PM
#3
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"Does anyone know how well the engine will run without the O2 sensor? I'm wondering about mixing in some 110 leaded race gas, without the O2 sensor. "
It would work OK, just run rich at mid-rpm/partial-throttle ranges. The DME automatically enriches the mixture thinking an O2-sensor failure has occured and defaults to the rich end of its dithering-range I think. Not sure on what the % correction based upon O2-sensor input is, but I've seen something like 5% richer on the dyno.
And at full-throttle on the track, there's no difference because the DME drops into open-loop mode using only the pre-programmed fuel-maps on the chip with airflow correction. The DME switches to open-loop based upon TPS position and velocity, something like greater than a 60-degree change in under a certain amount of time. Otherwise, you can actually run closed-loop with O2-feedback all the way up to redline if you're not flooring it.
It would work OK, just run rich at mid-rpm/partial-throttle ranges. The DME automatically enriches the mixture thinking an O2-sensor failure has occured and defaults to the rich end of its dithering-range I think. Not sure on what the % correction based upon O2-sensor input is, but I've seen something like 5% richer on the dyno.
And at full-throttle on the track, there's no difference because the DME drops into open-loop mode using only the pre-programmed fuel-maps on the chip with airflow correction. The DME switches to open-loop based upon TPS position and velocity, something like greater than a 60-degree change in under a certain amount of time. Otherwise, you can actually run closed-loop with O2-feedback all the way up to redline if you're not flooring it.
09-16-2002, 05:46 PM
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Thanks, I thought it would probably be fine. I knew that WOT it made no difference I was wondering how it would idle/cruise because I do drive to the track.
--Brian
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--Brian
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09-16-2002, 06:41 PM
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Actually, if I unplug my O2 sensor, I have more HP and TQ on my car at WOT. Of course, this probably means there is something wrong with my car (I guessing here), but I've never had anyone be able to figure it out....
09-17-2002, 09:35 AM
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If you are running your car at the track, the mid-range richness is enough to cause an engine stumble. I saw the problem alot before I installed a new O2 sensor when I came off throttle for a medium speed turn and then came on the power around the apex. It was not a serious problem but I would say it would probably add a second to my Watkins Glen times.
