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Re: 1998 O2 sensor



At 12:44 PM 6/28/00 -0500, you wrote:

>     If utilizing the 98 PCM OBD2 config , you'll need to utilize the Pre -
> Post Ho2s on each side
> of the engine since the PCM is calculating Bank to Bank Fuel Trim based on
> all 4 sensors.
>   Len

About every 100 seconds the VCM compares the switching time intervals of the 4 HO2S,
it also uses the L&R Bank 2ndary HO2s to "Monitor" cat Oxygen Content Ratio.
In OBD2, if the VCM can't get all 4 switch " Expected" responses in"time" , then expect at the very minimum S hort T erm and L ong T erm Fuel Trim Adjustments. There's
more , I'd say give the VCM what it wants and use the 4 Heated Oxygen Sensors.
All this information and more is defined in S.A.E. J1850 Specification [s] , Heated Oxygen Sensor Tests and Diagnostics. Failure of the heater circuit can also cause Scew of the Fuel Trim Adjustments. This is the basics , gets more complicated going
forward !

 Len

Can someone tell me if the after cat O2 sensors are used for any actual
engine calibrations or not on the 96-00 engines. Or do the after cat sensors
just throw a trouble code if there is something out of whack with the
catalytic converter?

Thanks
Paul Washburn
lpwcruzr@netzero.net


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