Why an Oxygen Sensor?
09-07-2006, 10:08 PM
#16
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Originally Posted by Campeck
ae you sure? Ive always heard that to be safe EVERY cars computer will default to as rich as possible to avoid engine damage. and when mine was broken i went from a bout 470miles to a tank to 250....i cant believe i used that much gas cause it was always at stoich.
I have a switch on the O2 sensor line near the DME and measured 0.5 V (on the input to the DME) when the O2 sensor was switched out. That way Danno could adjust the base-map without closed loop interference.
Any sensor has a default setting if the line gets broken and it makes sense that it is 0.5 V (for the O2 sensor) so the DME doesn’t adjust to the edge of its authority range. That some people report running rich with a broken sensor could very well be that the O2 sensor normally compensates for a rich base-map or a high pressure FPR. To have minimum compensation the base-map should be as close to stoichiometric as possible in closed loop configuration.
In the above we are talking less than (somewhere between) 60 to 70% TPS, where it switches from closed to closed to open loop.
True, running continually rich does kill cats, especially older types with more catalyst.
Laust
PS My old K26-6 turbo was so eager, that I occasionally reached max boost (23 psi) in closed loop configuration so to avoid pinging, I had to counter-intuitively step on the gas even more to get into open loop.
