A Primer on O² Sensors - Sorry Long

[Tool Pants]

You look at the waveforms to see how the sensors are operating.

[RandallNeighbour]

On that pic, the top two aren't working at all, the 3nd one is responding slowly and the bottom one looks fairly new. What's up with that?

[dcporsche99]

Hey Jim,
Just saw this thread and wanted to respond with a big "Thank you". This information is definitely worth reading and holding on to!! Now I get it!!

BTW, I finally had some time to finish the install of my pre-cats last night. Talk about a small work space!! I ended up buying a ten dollar 3/8" dr. with a flex head ratchet handle to start and finish the job. I didn't need this tool for the post-cats, but realized it's effectiveness very quickly! This was one time where I was glad that I got what I paid for!! Before I found this nifty tool I thought I would have to take down the exhaust or worse yet, go to my mechanic and be charged up the &%^ just for labor. Anyway, I am definitely very happy!! And with a new understanding of how these sensors work,....even better!!

...So, Randall --now I know what you mean about a big change in performance after changing all four sensors!!! My car never sounded so good ----just wonderful!! Thanks for your input regarding the sensor change. I know I will probably need to purchase a new MAF down the road ---but so far, so good! :dance:

[Rodger]

I recall at some point reading that O2 sensors developed voltage based on the reaction between platinum and zirconium. These may be old-style sensors, as I think I read it in my old Honda Civic service manual. I used the presence of platinum to justify the ridiculous cost (in my own mind) of new sensors.

On the F-15, the P&W engines are equipped with a set of EGT thermocouples which develop similar voltage through the reaction of an alumel and chromel probe exposed to combustion gases.

Good read, thanks, Jim!

[RandallNeighbour]

dc, it really does make a difference, doesn't it? Of all my performance "mods" changing out the sensors gave me the best butt dyno increase of them all.

I too am holding my breath concerning my MAF. It seems to be going strong, so I'm going to keep driving it until it up and dies on me. I'm betting a previous owner replaced it somewhere down the line. My car is 10 years old with 99k on it and it would have surely gone out by now I think...

[porschegeorg]

Jim, you are a walking-encyclopedia....or a breathing-google....either way I sure appreciate your knowledge!!