Re: O2 sensor Primer

[Angela Dupin <dupina@crisny.org>]

The obvious question: Why is there not a Bosch universal listed for my 
'86's 5kcst?
i'm currently using a Ford 3 wire from an unknown donor car with unknown 
history.  car runs great in open loop(cold) but hesitates and lacks 
performance when warmed.  any suggestions?

	all the best,

	Phil

> > On Sun, 1 Dec 1996, Angela 
Dupin wrote: > 
> > What difference is there between the various 3 wire Bosch Audi sensors, 
> > besides the connectors?  is the signal different?
> 
> Phil, & everyone else that is interested...
> 
> 	This has been discussed in previous threads, but I guess there 
> have been some problems with the archives, so for the benefit of those 
> that weren't here, or can't get to the archives, I'll recap briefly.
> 
> 	All oxygen sensors are alike basically.  They compare the oxygen
> content of the exhaust gas to a reference gas housed in a small chamber
> inside the sensor.  The difference between the two oxygen levels will
> cause a small voltage to develop between the two gases.  The reference gas
> and the general construction is designed so that the voltage is 0.5v when
> the engine is burning at stoichiometry(approx 14.7:1.) A richer mixture is
> indicated by a greater voltage while a leaner mixture is indicated by a
> lower voltage.  O2 sensors are extremely accurate at or near stoich, but
> they loose their accuracy as the mixture deviates from stoich by more than
> 10%.  There are many factors that affect their accuracy, but that is a
> discussion that is far more advanced than I can lead. 
> 
> 	The variations in the commercially available sensors are mostly 
> centrered around heaters, and ground locations.  The single wire sensors 
> have a signal output, and the sensor case is the ground.  The 3 wire 
> sensors have an internal heater which bringhs the sensor up to operating 
> temperature mroe quickly, and will keep it at that temp if you idle the 
> engine for too long.  The 4-wire sensors add an additional wire for a 
> separate ground, in case you are using an exhaust manifold material which 
> does not conduct electricity.
> 
> 	In case some of you are saying, "But there _are_ other types of 
> sensors!" I would add that there is a new sensor called a wide band 
> air/fuel ratio sensor which stays accurate from about 12:1 up to over 
> 22:1 air/fuel ratios.  These are very expensive, but nonetheless, a few 
> manufacturers are using them, particularly in the newer "lean-burn" engines.
> 
> 	That's the short form.  HTH
> 
> Later, ---------------------------------------------------------- 
> Graydon D. Stuckey 	'85 Mazda RX7 GS, no toys 
> graydon@apollo.gmi.edu 	'86 Audi 5000 CS Turbo Quattro, has toys
> Flint, Michigan USA	'89 Thunderbird SC, lotsa toys
> 
> 
>