What do either one of these do? What is it used for? Thanks in advance.

 

Narrow band:
A narrowband sensor's job is to keep the car at 14.7 AFR by and unlike a wideband sensor in their operation the voltage output is exponential. So any small deviation from stoichiometric causes the voltage to drop to its lowest point 0.1v or the highest 0.9v. The voltage is produced by an electrochemical fuel cell called the Nernst cell. Its two electrodes provide an output voltage corresponding to the quantity of oxygen in the exhaust relative to that in the atmosphere. The car simply adds or removes fuel based on when the sensor switches from low voltage to high.

Wideband:
These are used to measure the how rich the air to fuel mixture is after the burn in the cylinder. This is important for tuning purposes by optimizing the fuel burnt you can get more power out of the car with less chance of knock. A much more technical explanation is below

Technical:
The sensor itself is an oxygen pump where it pumps oxygen from the outside into the sensor cavity. An electrical current through the pump cell transports the oxygen ions. If the current flows in one direction, oxygen ions are transported from the outside air into the sensor, in the other direction oxygen ions are transported out of the sensor to the outside air. The magnitude of the current determines how many oxygen ions/second are transported, just like the electrical current through a fuel pump determines the fuel transport rate.

In a rich condition the WBO2 controller regulates the pump cell current such that just enough oxygen ions are pumped into the chamber to consume all oxidizable combustion products. This basically produces a stoichiometric condition in the measurement chamber. In a lean condition the controller reverses the pump current so that all oxygen ions are pumped out of the measurement chamber and a stoichiometric condition again exists there. The pump cell is strong enough to pump all oxygen out of the measurement chamber even if it was filled with free air.

 

thanks again roadspike.

so when would i need one? basic bolt-ons probably won't need this? if i get some cams, will i need this?

 

on a stock 2003 evo 8. which sensor is the wideband sensor? front or rear. I replaced both sensors a while back cause i was getting a CEL and the code reader said it was the sensors. however, now my car is running pig *** rich (even after a tune) and nothing i do seems to make it any better. so im thinking i replaced a sensor with the wrong type.

 

I think a wideband o2 gauge is a wise investment no matter how many mods you have done to your car. In terms of importance, I'd put it right behind the boost gauge.

 

The Evo doesn't not have a wideband sensor on the vehicle. The only vehicles that i know come with one are the new flex fuel Chevy's and possibly some others. The reason most manufacturer's don't put these on is due to the sensor being more frail and it costing more per unit.

As for the rich condition if you haven't replaced the front sensor with an OEM one than you may try that. Also reset your ECU by unplugging the battery for couple minutes with the lights on to try and reset the fuel trims.

http://www.oxygensensors.com/catalog.php?&pkey=1423022

 

narrow band is for pretty and to be a cool ricer
wide band actually gives u accurate readings and can tell you if ur car is running rich or lean

 

Came across this topic, very good info I had been wondering the same thing, especially how it works. One question not to thread jack, but where is the recommended location to install a wideband sensor on a car with a high flow cat?

 

I recommend right before the cat try to place it as vertical as you can to avoid moisture dripping on the sensor during warm ups my own is placed just slightly above level. You also don't want it in extreme heat so the stock location for the front o2 isn't really an option.

 

excellent info RoadSpike