heated oxy. sensor mod.

[moif]

Is there any way to replace my single wire (unheated) oxy. sensor with a
heated sensor in my `87 305 classic? Any ideas on how complicated that mod. would be if possible.
Thanks.
moif

[1986Z28]

why 3 threads

[moif]

Have no idea why that happened!!!!

[gmtech79]

mind if I ask why?

[PeteA216]

What is a heated Oxygen sensor? If its what im thinking, I'm not sure its possible.

[moif]

A heated oxy. sensor has an extra wire to it to preheat the sensor so there is no lag time before sensor can give accurate info to the computer to regulate fuel mixture. My unheated takes forever to heat up and during that period I`m only getting 11 mpg. After it heats up I`m getting around 17 mpg
stop and go. A heated has 3 wires to it.
moif

[Blue Bowtie]

Originally Posted by moif

A heated oxy. sensor has an extra wire to it to preheat the sensor so there is no lag time before sensor can give accurate info to the computer to regulate fuel mixture. My unheated takes forever to heat up and during that period I`m only getting 11 mpg. After it heats up I`m getting around 17 mpg
stop and go. A heated has 3 wires to it.
moif

Heated O²s have either three or four wires. The three-wire versions were only used for a few years, and in a few applications, and are therefore usually more expensive.

HO2S retrofits are very common for vehicles where headers are installed. Usually, the heat loss of the tubes plus the distance of the collector from the exhaust flange makes them necessary.

If you are not getting adequate O² heating within the period of check time for the ECM, an HO2S is a good idea. You cna install one and simply connect the heater to ain ignition circuit, as many people do, or do it the proper way and get a lot longer life from the sensor. In vehicle that came equipped with HO2s from the factory, the PCM usually regulates heater current to provide fastest heating and prolong the sensor life. You can emulate this with your ECM, even though it was not designed for it.

Construct a circuit like this with a relay and fuseholder, and the heaters will operate at full power until the ECM reaches Closed Loop Mode (where you are getting better fuel mileage):



Pin A3 of the ECM is used to control the solenoid for EVAP purge. This only enables during Closed Loop Mode. Closed Loop can only occur if the ECM is receiving adequate signal crosscounts from the O² sensor (hot and active sensor). Therefore, this circuit will operate the heaters only on startup and whenever thay happen to cool down enough to stop reporting, so the heater element will not be running all the time.


If this ai a carbed engine (not sure in '87) and you're looking for more mileage, you may want to check the lean and rich stops on the carburetor, and set the hot idle Mixture Control Solenoid activity (duty cycle).

[Blue Bowtie]

Actually, the diagram may be a little misleading. Some HO2S have those wire colors, but most GM sensors use this scheme:

[moif]

Thanks for all the help, I`ll give it a try.
moif