Could someone explaing the purpose of four O2 sensors?
Thanks,Don
What is the reason for four O2 sensors?
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Q45tech
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- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: What is the reason for four O2 sensors? (duck3986)
Each bank [4 cylinders or 3] can be separately fine tuned by varying the injection open time [+- 20%] by the O2 cross over count [rich, lean , rich,lean] to zero in on 14.7AF [at steady cruise rpm].
OBD2 requires that that cats condition be checked [are they working as they should] have they degraded from age >100k. The second set of O2 sensors are very different. They look for the time delay reaction that shows the cats are working.
OBD2 requires that that cats condition be checked [are they working as they should] have they degraded from age >100k. The second set of O2 sensors are very different. They look for the time delay reaction that shows the cats are working.
Re: What is the reason for four O2 sensors? (Q45tech)
With 95k miles on my '98Q I was thinking of replacing them. Is it more critical to replace the first set (closer to engine) or the 2nd set?
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psychic_mechanic
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- Car: the world's ugliest civic
Re: What is the reason for four O2 sensors? (duck3986)
I'm pretty sure the first two (upstream) closer to the engine are the ones that feed the engine information about Rich/Lean.
The second set are sometimes called cat monitors, because they only "throw a code" if your cat is not working.
The first two would have more effect on how the engine runs, but OBDII has pretty specific parameters that the sensors need to meet or they "throw a code". This is much better than the previous systems where the sensor would have to be pretty much grounded or open before it would set a code.
The second set are sometimes called cat monitors, because they only "throw a code" if your cat is not working.
The first two would have more effect on how the engine runs, but OBDII has pretty specific parameters that the sensors need to meet or they "throw a code". This is much better than the previous systems where the sensor would have to be pretty much grounded or open before it would set a code.