neo, you are 98% correct, but when the ecu sees a constant issue with the 02 sensor (or so it thinks) it throws the check engine light and reads off pprom thus bypassing o2 sensor readings because it thinks the 02 sensor is fubar.
yeah i wasnt disagreeing with that in the least bit, thats what open loop is =P. Just saying what it takes to put the vehicle into closed loop.
During WOT operation, the ECU ignores 02 sensor input.
in this specific to this vehicle or is this a in general thing? Curious
I am not sure to be honest. It’s definate for DSM/3S. Remember, pre OBII, the manufacturers had their own protocol. I am curious if anyone has the answer to this? I assume OBDII all do the same thing now?
anything with a narrowband sensor definately. newer cars with widebands might use them more.
the narrowband o2 sensor’s is only show rich or lean relative to stoich. At WOT throttle the ECU isnt seeking stoich, but rather a richer mixture that the narrowband can’t give accurate readings for. widebands on the other hand can show much more specific readings across a larger range of air fuel ratios. newer computers might use them for WOT but im not sure.
Sorry for bringing up an old thread, but I just wanted to let those who helped me out with suggestions know the current outcome.
After my timing belt broke, the head was rebuilt. That and the 02 sensor was replaced. No issues whatsoever now.
I had replaced the BOV when I first mentioned the problem, and it was great for a couple of weeks before it started happening with that one. All I can assume is that the boost/vac leak was in the head somewhere. Or shitty timing.
Car runs perfect now though, and I couldn’t be happier.