Originally Posted by Corrolla clone
Why is it that the GM guys just add a couple of wires to run a heated O2 sensor in place of the single wire unit? When the heated version is used, you get a finer/better reading (leaner?) than the 1 wire unit. That's also with only using the single wire O2 sensor ECM too (power supplied for the heater comes from the fuse box).
You do realize you're talking about a company that went bankrupt
because they have such crappy products right? There's absolutely difference in meals you get from S.F.'s Laurel Court restaurant versus any Burger King. Toyota uses ECM-controlled heated O2-sensor so constant-temperature can be maintained. When engine's cold, when you're flooring it, when cruising on freeway all require different contribution from heater.
Proper double-blind testing is also needed. In GM example, exact
O2-sensor must be used. With and without heater turned on. Comparing two different sensor of different types and ages yields invalid data for comparison due to extra variables. You'd also need to use exact same wideband O2-sensor as control to verify actual AFR between those two tests. And it must be something other than LM-1 because that unit uses analogue gauge without regulated reference voltage. Exact same AFR displayed would vary depending upon state of battery charge and whether you had headlights turned on or off.
First, if the O2-sensor actually needed
a heater, then some engineer messed up. O2-sensor was placed too far from exhaust valves. Not on Toyotas, they did it perfectly. Primary 1-wire O2-sensor close to exhaust-valves and secondary 4-wire heated O2-sensor further downstream. Only 2nd/downstream O2-sensor needed heater because it was placed 3-feet from exhaust-valve and needed its own heat supply.
Second, IF you replaced Toyota's primary O2-sensor with heated one, there will be absolutely zero difference in readings because non-heated one will put out exact same signal as heated O2-sensor due to optimum placement. Retrofitting car with more modern ECM to run heated O2-sensor will yield no difference in exhaust readings and no difference in performance or MPG.
newer OBD-II cars DO come with heated primary O2-sensor, but that's purely for quicker transition to closed-loop operation and lower-emissions. Again, nothing to do with accuracy or performance and specific ECU + matching heated O2-sensor needed.
Have you even looked at O2-sensor signal on your car with oscilloscope? How would you even know if signal is not accurate?