Re: O2 SENSORS answered

[turbo@steelcity.net]

waves@epix.net wrote:
> 
> Answering the question about O2 sensors, yes, in all cars they are very
> important to the running of the car. They are not the most important sensor
> though, the water temp one usually is. Anyway, the O2 sensor sniffs the
> Oxygen content of the exhaust compared to the oxygen content outside the
> exhaust. From that, and with the help of heat (600 degr. needed), the
> chemical Zircrhomium (and others) emits an electrical charge, as the sensor
> is grounded by the exhaust/engine. The computer puts out a reference voltage
> of aprox.  .5 volts. This voltage is compared to the voltage coming out of
> the sensor to determine the stoichiometric (sp?) ratio of the fuel/air
> mixture. If the ratio is rich, say 13-1 (14.7-1 being ideal) the voltage
> from the O2 sensor will higher than .5v and the computer will alter the
> mixture. Vice/versa, 16-1 is lean and the poooter will richen the mixture.
> 
> If the sensor is deleted, or is bad, the computer will likely make up it's
> own value, right around .5 volts, which if the engine is in a decent state
> of tune, will run almost as well. To check a sensor, unplug the lead wire
> (always black) and hook up to a simple volt meter. The engine exhaust must
> be at least 600 Degr. F. The voltage should be jumping between .3 to .7
> volts or there abouts. if it moves very slow or not at all, the sensor is
> dead. You can also check the reference voltage from the pooter and it should
> be between .4 and .6 and very steady. Hope that helps!!
> 
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><
>                        Rolf Mair is: waves@epix.net
>         Racing Resume for Sponsors/Corvettes for sale/Racing Pix @
> http://www.sevenwaves.com
>     Head Coach and Founder of the Seventh Wave jr. Ski Racing Team @ Doe Mt.Pa
>                1994,95,96 East Coast USA SCCA Solo 1 Champion
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><
	CAUTION TESTING THE O2 SENSOR WITHANYTHING BUT A DIGITAL VOLT METER
WILL DAMAGE THE SENSOR AND REQUIRE REPLACEMENT.
Rolf is correct the sensor must fluctuate around .5 volts but the
computer on the newer AUDIs look for it to change more than 125 times
per second and even good meters wont show this an oscilliscope is
req.But the onboard diagnostics check this and usually will detect a
fault.
turbo@steelcity .net