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Old 05-29-2012, 01:37 PM
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Originally Posted by sbchevfreak
Here is how it works, without getting into too much detail:

The 02 sensor is just that, it senses how much residual oxygen in in the exhaust stream. There is a material in the sensor tip, that generates a voltage between 0v and 1v, roughly, when exposed to oxygen. The sensor has to be at or above 660* F to work, which is why the old 1 wire sensors were mounted in the manifold, so that the exhaust would heat them quickly. At .450-.500 volts, this is the "ideal" mix. Above and below, rich/lean. This cycles in the milisecond range. A fixed voltage will not work, and you cannot manually switch it fast enough.

fbird's idea with the 4 wire sensor mounted furthur down the pipe is a good one. The sensor will be every bit as accurate, likely even more so, as the original. The heated sensors were brought into use because the 1 wires had a tendancy to cool off below threshold, and drop the fuel system into open loop, increasing emissions. The solution was to add a heater circut that was ECM controlled to maintain sensor themp above threshold. In reality, all the early ECM did was turn on the 12v feed to the heater when the car was stared, and turn it off when the car was shut off, so a switched power realay feeding 12v to the heater circut does exactly the same thing.

Your methods will not work. It is time to be rational, and realize that by the time you "engineer" a complicated jimmy fix to fool the ECM, you will have spent more time and money than the car is worth. If you do not want to put in a heated sensor down stream of the original one, you need to remove the original sensor, and replace it. There is no in between.

Going on the limited understanding I had of the 02's physical and interactive characteristics and knowing that the voltage cycled through a very limited range, that was the direction I was facing. Now when you say millisecond cycling, I can understand that. I have not given up on replacing the original sensor or installing another further down stream. Over two days work has been focused on removing the old one. I don't give up easy. I'm throwing ideas around for feedback. All I'm hearing is it's impossible to fool the ECM, but a MAP enhancer does just that, right? Nothing is impossible. But as I continue until the repair is completed, I can't take a purist outlook & say it can't be done. I expected to hear more "what if's", but I guess most don't want to break ranks from the norm. It's that sheep thing that civilization is built upon I guess. Well, I'm not going to butt my head up against that wall. I'll let you know if and when it can be done. Computers and programs can control & deceive other computers. Cost is no factor to achieving something worthwhile or to prove something can be done differently. But Time, Ah, time is a different matter. Priorities come into play. But I stick by the fact that many things CAN be done. I'm glad you posted sbchevfreak. I had your post in a tab from Tempting new air fuel ratio afr analog gauge. Saved me from looking in the manual for those specs. Good day friend.
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