My O2 sensor will not change volatge once the car is at operating temperature. I unplug the senor and measured the volatges it was a steady voltage. I heard that if the O2 sensor is working properly it sgould change voltages like 2 times per second. Also like to point out that is sensor is only 1 yr old and when unplugged the computer will not set a code. I checked wiring lead from O2 to ECM and it is fine.

The car is a stock 86 ROC auto except for speed density. I was wondering if it is possible that the O2 sensor is not heating up to the required 600F for operation is it possible??

 

The sensor output voltage changes in response to the mixture ratio change made by the ECM, once it has gone into closed loop operation. Could be the ECM is defective, if it does not set a code with the O2 sensor disconnected, or with the O2 sensor at a constant voltage in closed loop. What is the voltage output of the O2 sensor in closed loop?

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Tim

1992 Z28, 305 TPI 5 speed, 12.1 sec @ 114.7 mph

1984 Berlinetta 305 TPI Auto, 13.8 sec @ 99.7 mph

 

you need to like wait a while...(drive the car with the O2 sensor off for it to throw the code.

(needs time to go into closed loop)

 

i heard that ur not supposed to check voltage from the O2 cause it can screw up the sensor, acording to the manual anyways. i don't know im just tired.

also, isn't there a SES code for an O2 sensor that doesn't change voltage?
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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

[This message has been edited by breathment (edited October 22, 2001).]

 

See I am not sure that the car is going into closed loop I am pretty sure that the car is staying open loop all the time. But the O2 sensor will change voltages I can't exactly remember the voltage reading but I think it was like 400mV constant, I will check it again and post it up as soon as I get to check it.

 

If the voltage is around 400 to 450 mv constant, with the ECM connected, then the voltage you are measuring is probably from the ECM & the sensor is either open & needs to be replaced, or the connection between the sensor & the ECM is open (if you are measuring the voltage at the ECM).

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Tim

1992 Z28, 305 TPI 5 speed, 12.1 sec @ 114.7 mph

1984 Berlinetta 305 TPI Auto, 13.8 sec @ 99.7 mph