O2 sensor questions...
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Joined: Nov 2000
Posts: 1,003
From: Grandville/ Grand Rapids, Michigan
O2 sensor questions...
I have the SLP shorty headers on the Iroc, yet I don't think that my O2 is functioning properly. The reason I say this is because of the datalogs and also a digital VOM meter test. It seems that when in closed loop, the O2 sensor stays right at .4 mV and usually never moves at ALL! I have seen it go to .5mV once but thats it.
I was recommended a 3 wire O2 because its heated and also provides a remote grounding location. The ground was also another area I was concerned with. I am not sure that the sensor even has a good ground. The threads are all clean ans shiny still.
So, if I use a heated O2 will it be detrimental if I don't need one? I know guys with longtubes nearly REQUIRE them but I have yet to hear of Shorty header guys needing them.
------------------
-Brad C?
355ci '89 Iroc-Z Red, T-tops, power everything, A4,New 10 bolt w/ 3.73's
Trans-Go shift kit Corvette Servo,Accel 8.8mm wires,Flowmaster 80 series ,K&N's, !MAF Screens, Hollowed out airboxes,homemade Subframes. Kieth Black pistons 10.3:1, Comp Cams 270H (.495/.502 218*/224* 110*LSA) & valve springs, SLP 1 3/4" headers, TCI 2400 stall, Dual Roller timing chain, 2 3/4" I-pipe.
Full street trim best run:14.799/mph:93/60': 2.02 (last year) New Times to come.
New times: 13.732 @ 99.30 on a 1.878 60'
Pics of the Iroc
I was recommended a 3 wire O2 because its heated and also provides a remote grounding location. The ground was also another area I was concerned with. I am not sure that the sensor even has a good ground. The threads are all clean ans shiny still.
So, if I use a heated O2 will it be detrimental if I don't need one? I know guys with longtubes nearly REQUIRE them but I have yet to hear of Shorty header guys needing them.
------------------
-Brad C?
355ci '89 Iroc-Z Red, T-tops, power everything, A4,New 10 bolt w/ 3.73's
Trans-Go shift kit Corvette Servo,Accel 8.8mm wires,Flowmaster 80 series ,K&N's, !MAF Screens, Hollowed out airboxes,homemade Subframes. Kieth Black pistons 10.3:1, Comp Cams 270H (.495/.502 218*/224* 110*LSA) & valve springs, SLP 1 3/4" headers, TCI 2400 stall, Dual Roller timing chain, 2 3/4" I-pipe.
Full street trim best run:14.799/mph:93/60': 2.02 (last year) New Times to come.
New times: 13.732 @ 99.30 on a 1.878 60'
Pics of the Iroc
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Joined: Mar 2001
Posts: 3,249
The heated O2s are not magical. All they do is help the sensor get to the correct range ASAP. In your case, probably because of the backpressure or lack of it, your sensor is cooling off too fast. The heated sensor will help.
3 wire sensors have 1 lead to the ECM, 1 to the ground and 1 hot (switched hot). 4 wire ones have the same except that the last leads to the ground for the sensor.
Wanna see if you have a good ground? Take a DVOM and set it to measure resistance. Stick one end on the header pipe and the other on the body of the sensor. Next, stick the sensor end onto a section of the pipe. Compare the readings. If, as I suspect, the readings are similar then you have ground at the threads. From there, see the readings betweent the header and the frame ground
3 wire sensors have 1 lead to the ECM, 1 to the ground and 1 hot (switched hot). 4 wire ones have the same except that the last leads to the ground for the sensor.
Wanna see if you have a good ground? Take a DVOM and set it to measure resistance. Stick one end on the header pipe and the other on the body of the sensor. Next, stick the sensor end onto a section of the pipe. Compare the readings. If, as I suspect, the readings are similar then you have ground at the threads. From there, see the readings betweent the header and the frame ground
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