o2 price?

[thergen at svn.net]

Both the isolated ground O2 sensor and shell grounded 4 wire O2 sensors
may have valid applications.  For the shell grounded O2 sensor, the
"floating"  ground wire may be a shield as someone alluded to previously. 
The isolated O2 sensor would give more accurate results if it's referenced
to a ground at the ecm (all grounds are not equal). 

They're obviously not direct replacements for each other.  That wouldn't
be the first error in an auto part stores cross reference list (a rather
widespread error it seems). 

Tom

On Wed, 9 Jun 1999, David Cooley wrote:

> At 04:17 PM 6/9/99 +0100, you wrote:
> >Can you elaborate a bit more on what the extreme problems with the ECM are.
> 
> 
> The sensor, not being grounded to the outer shell, causes the inputs to the 
> ECM to "float"... mine went to -2.5 volts and made the ECM thing the engine 
> was starving for fuel...  The ECM compensated by going full rich and the 
> engine started chugging, missing and pouring black smoke out the 
> exhaust.  At first I thought the new O2 sensor was bad and made autozone 
> give me a new one... same thing... After a couple hours of playing, I 
> hooked a wire from ground to the wire that should have been grounded to the 
> shell of the O2 sensor and it ran right.  Pulled it out and checked with an 
> ohm meter, and it was totally isolated from the shell... Checked the old 
> AC, and the low side of the sensor was connected directly to the 
> shell.  Bought a new AC and all was well again.
> 
> 
> >When you say they are isolated from ground do you mean the ground wire is
> >not physically connected to the outer metal casing?
> 
> Exactly!
> 
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> David Cooley N5XMT Internet: N5XMT at bellsouth.net
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