1Revvin7

ok, ok, ok but is it true that wideband o2s burn out fast?

vosko

should last a year. it depends how much you drive. they aren't THAT expensive to replace the 5 wire O2 sensor

1Revvin7

Well could i take it out when i need to tune etc, so it would last forever? or do u guys just keep it in their and monitor it @ all times, and do these "kits" come with some type of digi gauge?

vosko

i am leaving my A/F gauge in the whole time. new O2 sensors are cheaper than engines.... the FJO comes with a digital read of the exact AFR... i'll take pix when i get my car back!

1Revvin7

ok cool

SPOautos

The main reason you cant tune with a egt alone is becuase there are other things besides a/f that can affect the temps, like the fuel your running and the timing your running.



The more retarded the timing is the higher the egt's will be.



Also lets say your running real rich and you have the stock ignition system and its not combusting ALL the mixture, well a lot of that is going to burn as it goes thru the exhaust manifold which is going to cause your egt's to go way up which is going to make you think your running lean which is going to make you add more fuel and just make the problem worse. You timing being off will do the same thing.



The BEST thing is to have BOTH egt and wideband.



HOWEVER



if you can only get one the wideband is far more importand and easier to use than a egt.



There are prob only a handfull of people in the world that are good enough rotary tuners to do it with a egt only.......and I'd prob have to say your not one of them lol



STEPHEN

1Revvin7

interesting.

So how do wideband o2s measure afr? not by temp right.

Jim Swantko

Snagged from Robinette (hope he doesn't mind)... This is a great explanation!



============

The oxygen sensor detects oxygen in the exhaust in a way similar to a battery cell. Platinum layers on the inside and outside of the probe act as electrodes. Zirconium dioxide between the layers of platinum acts as an electrolyte. The inside layer of platinum is exposed to the air in the engine bay, the outer layer is exposed to the exhaust. When the O2 sensor is hot it generates positive voltage between the two layers of platinum. Negatively charged oxygen ions in the exhaust are attracted to the platinum and reduce the voltage that the Engine Control Unit and air/fuel gauge reads.



That's why a rich mixture = higher voltage from the sensor (more gas = fewer negative O2 ions to drop the voltage) .

SPOautos

Well, its acutally much more complex than just measuring temp, Jim covered it pretty well and i think that is just for a regular O2 sensor, not an actual wideband.



The temps can affect a wb though, most of the time they need to stay between like 400C and 800C exhaust temps to be accurate, this is why most people put thier wb in the bottom of the dp so it doesnt get too hot. This is why most sensors are self heated to make sure they stay within the correct temp range.



As long as your sensor stays between those degrees it will analize the exhaust and tell you the correct a/f ratio.



It would almost be next to impossible to use a egt gauge and tune to 11.5:1 across the board. You tune your fuel using the wideband then keep an eye on the egt gauge to make sure your temp are not getting too hot, especially when changine timing.



STEPHEN

SPOautos

Also a wideband is MUCH faster than a egt (and this is prob the most important reason to go wb)



I can datalog my wideband in about 50rpm increments(really more like 25rpms), then pull it up on the computer and see that at 5000 my af was 11.7 then at 5050 it was at 11.6 then at 6000 it was at 11.4 then at 6520 is is at 12.1 so i go to 6520 cell and add fuel. THAT IS HOW YOU FINE TUNE A ROTARY TO NOT BLOW UP!!!!!!



This is at WOT and there is no way that no matter what kind of egt you get or how much money you spend in it you'll get that kind of resolution. They are slower to react, if you hit a hot spot at 5000rpms at WOT your egt isnt going to tell you till your at 7500 rpms because rotaries run thru the rpms so fast, if the hot spot is only for about 50rpms and your at wot its probably never going to tell you there was a hot spot.



You can not safely and effectively fine tune with a egt gauge in my opinion. I catagorize it as just a safetly device, not a tuning device.



If you want to start tuning you need to do it right the first time. You cant NOT half *** it or else you'll be buying a new engine. When was the last time you saw a dyno tuner tuning a customers car with a egt gauge??? prob never and if you have what ever you do dont take you car there lol



STEPHEN