I know alot of people have asked this question (me included) but everyone seems to have a different answer.

What is the easiest or the best way to change from 5 wire to a 4 wire o2?

Can you use 4 out of the 5 wires in the plug and wire a 4 wire plug in or do you need to wire directly to the ecu?

Using a 4 wire cars engine harness like a gsr would be plug and play but for people like me who used the vx harness, we are left with a plug and are not sure what to do. Anyone who has information that is known to work please reply so we can archive this!

 

TTT

 

I will try to help a bit. Here are the connections for the five wire:

Pin 1 Heater Supply Orange
Pin 2 Heater Return Yellow
Pin 3 Calibration Resistor
Pin 4 Calibration Resistor
Pin 5 No connection
Pin 6 Voltage Sense Cell Red
Pin 7 Ion Pump Current White
Pin 8 Sensor Common Black

The colors are the wires on the NTK 5 wire Sensor. The heater on the five wire sensor takes 10.5 volts at around 1.2 Amps, a little less current when hotter. The sense cell is much like the sense cell on a 4 wire. Pin 8 would be like sense cell negative, and Pin 6 would be the sense cell positive. At stoichiometric there will be about 0.450 volts positive between pin 6 and 8. Pin 7 is unique to the five wire it supplies + and - about 6 milliAmps to an ion pump cell. This current is modulated to keep the sense cell exactly at 0.450 volts. Reading this oxygen ion pump current and comparing with a calibration table gives you the fuel air ratio in the exhaust stream. A 5 wire sensor is very different than the 4 wire. They are not interchangeable.

Help me with what exact substitution you are trying to do and I will try to help. Are you trying to use the 5 wire as a 4 wire? Not a good bet. Are you trying to use a 5 wire harness with a 4 wire sensor and 4 wire ECM? Then these color codes may help.

PS If you have an old 5 wire sensor, I would be interested in it. I need a used 5 wire for some tests. IM mail on it.

Regards,
BigMoose



[Modified by BigMoose, 11:25 PM 8/7/2002]