Extreme rich condition

[-=Jeff=-]

There is something going on with the o2 if it is not changing from 0.. could be anything.. this is where the harness wiring diagram becomes very useful

[Perry Mitchell]

I agree. I will follow the O2 sensor wires back to the computer and see which pins they are connected to.

[grahambehan]

In your first frame with the engine not running, both sensors are reporting around 450 mv, so the heaters are working and the sensor circuit is reporting at that time. I would suggest swapping the sensors from side to side and see if it follows the sensor or stays on the right.

Graham

[tpepmeie]

Graham, from what I recall, the calibration sets the initial startup value to .450 volts. This happens in the initialization routine. Once the engine starts the sensor reports back the actual voltage.


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[Perry Mitchell]

I believe I have found the problem with the right hand O2 sensor. I got my original Bosch sensors from the wrecked ZR out of storage and compared them with the ones in the car now. The three wires on the Bosch sensors had the black wire connected to the weatherpak connector at the C location. My right side sensor was wired the same as the Bosch sensor BUT the left hand sensor had the black wire at the A terminal. If anyone can confirm this with their originals, I would appreciate it. Thank you

[grahambehan]

Originally Posted by tpepmeie

Graham, from what I recall, the calibration sets the initial startup value to .450 volts. This happens in the initialization routine. Once the engine starts the sensor reports back the actual voltage.


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Todd, thats interesting, I'll have to check that.

Thanks
Graham

[tpepmeie]

Originally Posted by grahambehan

Todd, thats interesting, I'll have to check that.

Thanks
Graham

Had to dig out my source code to make sure I was remembering correctly.
In the calibration data, there is a value called "KO2FFO" which is the initial filtered O2 value when not running. In all the stock calibrations that value is .450v.

In the program, the O2 initialization routine starts at around address B26C, in the 91MY calibration. At first power-up, The program calls that calibration value and stores it in all of the various O2 RAM addresses. By the way, it does the same initialization for most of the key engine sensors (MAP, TPS, etc.).

To the OP, sorry for the hijack. I'll get back to lurking. Hope you get it sorted out.

[XfireZ51]

So Todd, are u saying that the sensor values we read at initial Power Up, not engine start, may not be the actual values for the sensors at that moment, ie TPS?

Also, how is the motor going Closed Loop w no X-counts coming from the right side?

[tpepmeie]

Originally Posted by XfireZ51

So Todd, are u saying that the sensor values we read at initial Power Up, not engine start, may not be the actual values for the sensors at that moment, ie TPS?

Also, how is the motor going Closed Loop w no X-counts coming from the right side?

re: the first question. not necessarily. what I described was the initialization at first power up, literally some of the very first sections of the program. After that, the various values get updated at specific intervals (milliseconds) based on sensor readiness checks and current values. Also, there are some variables which are stored in non-volatile memory even when the ignition key is off. That's the purpose of the "keep-alive" power (orange wire).

My supposition is that what we see in his datalog is the initialization value prior to startup, then replaced with the sensor reading after a certain amount of cycles have passed.

[Perry Mitchell]

Originally Posted by tpepmeie

Had to dig out my source code to make sure I was remembering correctly.
In the calibration data, there is a value called "KO2FFO" which is the initial filtered O2 value when not running. In all the stock calibrations that value is .450v.

In the program, the O2 initialization routine starts at around address B26C, in the 91MY calibration. At first power-up, The program calls that calibration value and stores it in all of the various O2 RAM addresses. By the way, it does the same initialization for most of the key engine sensors (MAP, TPS, etc.).

To the OP, sorry for the hijack. I'll get back to lurking. Hope you get it sorted out.

Todd, you didn't hijack. You just added some good usable information. I was wondering why the right sensor showed a value then disappeared.


I misspoke when describing the pigtails from the sensors. The left sensor was the same as the factory unit but the right sensor was wired wrong at the connector. I haven't run a new scan yet but I'm sure the sensor wiring was the issue with the sensor not showing a value.