Question on O2 Sensor's
06-24-2003, 05:01 PM
#18
Registered User
Join Date: Jun 1999
Location: Lowcountry
Posts: 939
It's possible to run open loop and have no O2 sensors at all. To do this you need the proper equipment to reprogram the PCM. This is definitely not recommended and would only be used with things like gigantic cams.
For the person with a '93. You probably won't benefit from converting to heated O2 sensors on a '93 if you're running coated shorty headers. The problem with full length headers (especially uncoated) and single wire O2 sensors is that O2 sensors are very sensitive to temperature. The exhaust gasses cool rapidly upon leaving the cylinder (well actually on the downstoke of the piston as well) and there isn't enough heat left to properly maintain an accurate O2 signal. Shorty headers should keep the O2 sensors close enough to the ports for satisfactory results. If you'd like too, or in some cases need to upgrade that is an option. You must splice in a new connector for four wire (as opposed to single wire) O2 sensors. The signal wire runs to the PCM like before but you must add the ground and switched power wires for the heater circuits... and of course purchase four wire, heated O2 sensors.
As for the person installing the longtubes and '97 engine in his car, it depends. If you are simply swapping the engine but keeping the current ('95) wiring harness, PCM, and knock sensor from the old engine, than all you need is the two O2 sensors. If you were swapping over not only the engine but all the wiring and PCM as well than you'd need to A.) install O2 simulators in place of the two post cat O2 sensors, B.) reprogram the PCM to disable the rear O2 sensors, C.) install cats and two more O2 sensor bungs behind the cats and the appropriate O2 sensors (four in all in this case) The reason the OBD2 cars ('96+) have four O2 sensors is because the first two in front of the cats are used to determine fuel delivery (like all the years before them) and the two O2's after the cats just monitor catalytic converter effeciency.
The only O2 sensors I would recommend for these cars are the AC Delco parts. People HAVE had problems with other brands (specifically Bosch). Dal charged me ~$36 for each heated O2 sensor last time + shipping. The non-heated O2 sensors for '93 cars should be cheaper.
For the person with a '93. You probably won't benefit from converting to heated O2 sensors on a '93 if you're running coated shorty headers. The problem with full length headers (especially uncoated) and single wire O2 sensors is that O2 sensors are very sensitive to temperature. The exhaust gasses cool rapidly upon leaving the cylinder (well actually on the downstoke of the piston as well) and there isn't enough heat left to properly maintain an accurate O2 signal. Shorty headers should keep the O2 sensors close enough to the ports for satisfactory results. If you'd like too, or in some cases need to upgrade that is an option. You must splice in a new connector for four wire (as opposed to single wire) O2 sensors. The signal wire runs to the PCM like before but you must add the ground and switched power wires for the heater circuits... and of course purchase four wire, heated O2 sensors.
As for the person installing the longtubes and '97 engine in his car, it depends. If you are simply swapping the engine but keeping the current ('95) wiring harness, PCM, and knock sensor from the old engine, than all you need is the two O2 sensors. If you were swapping over not only the engine but all the wiring and PCM as well than you'd need to A.) install O2 simulators in place of the two post cat O2 sensors, B.) reprogram the PCM to disable the rear O2 sensors, C.) install cats and two more O2 sensor bungs behind the cats and the appropriate O2 sensors (four in all in this case) The reason the OBD2 cars ('96+) have four O2 sensors is because the first two in front of the cats are used to determine fuel delivery (like all the years before them) and the two O2's after the cats just monitor catalytic converter effeciency.
The only O2 sensors I would recommend for these cars are the AC Delco parts. People HAVE had problems with other brands (specifically Bosch). Dal charged me ~$36 for each heated O2 sensor last time + shipping. The non-heated O2 sensors for '93 cars should be cheaper.
06-24-2003, 05:32 PM
#19
Registered User
Join Date: Mar 2003
Location: Houston, TX
Posts: 869
I am leaving the 95 wiring harness...so I guess all I would need is the 2 O2 sensors...there are 2 holes in the LT's...is that where they would go? I am then going to use 2 cats and a custom Y pipe...emissions...emissions...emissions. Thanks.
JOHN
JOHN
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