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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
89 GTA, L98 with Dyno Don's headers. What's a good source for a heated O2 sensor and with installation instructions. I understand I would be going from a 1 wire to a 3 wire. Is there a electrical connector adaptor, and where would you splice into for power ? TIA
It's about $10.00 cheaper from Summit Racing for Casper's 4 wire heated O2 sensor retrofit kit and about a buck cheaper for Casper's 12" "SQR" extension harness. IDK if you will need an extension harness or not. Casper's kit adds about an extra 4 inches. Measure twice and spend once
You probably want to know what is the difference between a 1, 2, 3, and 4 wire O2 sensor.
There is more nuance to this than how I have explained it. I tried explaining it as best I can as it applies to what you are doing here. Doesn't apply to a 2002 Trans Am or a 2018 Chevy Silverado.
1 wire O2 sensor the voltage signal the O2 sensor generates goes to the ECM and there is no dedicated reference ground signal to the ECM. The O2 sensor grounds through the body of the sensor through all the rust, corrosion, gaskets, and all the other dirty nasty crap.
3 wire O2 sensor is the same as a 1 wire O2 sensor but has a 12 Volt + and a ground for the heater circuit.
2 wire O2 sensor has a dedicated reference sensor ground wire back to the ECM.
4 wire O2 sensor is the same as a 2 wire O2 sensor but has a 12 Volt + and a ground for the heater circuit.
The '7165 ECM on 1986 to 1989 Mass Airflow systems is setup for a 2 wire O2 sensor with a dedicated reference sensor ground terminal and a O2 signal terminal.
GM being the cheap azzes that they are installed a 1 wire O2 sensor that grounds through the sensor body and ran the a wire from the dedicated O2 sensor reference ground terminal on the ECM to the back of the passenger side cylinder head and grounded it there. They saved a nickel though.
Connect the ground wire in the Casper's kit to either ground point in the first diagram above, connect the 12 Volt + wire in the Casper's kit to the 12 Volt + output wire of the fuel pump relay circuit. The O2 sensor's heater will only be on during fuel pump prime for 2 seconds and while the fuel pump is running.
I'm going to tag @Tuned Performance to hope he will look at my reply to make sure I didn't screw it up or if there is a better way to explain it or a better way to do it.
Last edited by Airwolfe; Mar 4, 2025 at 08:40 PM.
Reason: Spelling
It's about $10.00 cheaper from Summit Racing for Casper's 4 wire heated O2 sensor retrofit kit and about a buck cheaper for Casper's 12" "SQR" extension harness. IDK if you will need an extension harness or not. Casper's kit adds about an extra 4 inches. Measure twice and spend once
You probably want to know what is the difference between a 1, 2, 3, and 4 wire O2 sensor.
There is more nuance to this than how I have explained it. I tried explaining it as best I can as it applies to what you are doing here. Doesn't apply to a 2002 Trans Am or a 2018 Chevy Silverado.
1 wire O2 sensor the voltage signal the O2 sensor generates goes to the ECM and there is no dedicated reference ground signal to the ECM. The O2 sensor grounds through the body of the sensor through all the rust, corrosion, gaskets, and all the other dirty nasty crap.
3 wire O2 sensor is the same as a 1 wire O2 sensor but has a 12 Volt + and a ground for the heater circuit.
2 wire O2 sensor has a dedicated reference sensor ground wire back to the ECM.
4 wire O2 sensor is the same as a 2 wire O2 sensor but has a 12 Volt + and a ground for the heater circuit.
The '7165 ECM on 1986 to 1989 Mass Airflow systems is setup for a 2 wire O2 sensor with a dedicated reference sensor ground terminal and a O2 signal terminal.
GM being the cheap azzes that they are installed a 1 wire O2 sensor that grounds through the sensor body and ran the a wire from the dedicated O2 sensor reference ground terminal on the ECM to the back of the passenger side cylinder head and grounded it there. They saved a nickel though.
Connect the ground wire in the Casper's kit to either ground point in the first diagram above, connect the 12 Volt + wire in the Casper's kit to the 12 Volt + output wire of the fuel pump relay circuit. The O2 sensor's heater with only be on during fuel pump prime for 2 seconds and while the fuel pump is running.
I'm going to tag @Tuned Performance to hope he will look at my reply to make sure I didn't screw it up or if there is a better way to explain it or a better way to do it.
