My O2 gauge is getting some really bad values. I have a dash mounted gauge that seems to be reading correctly but the ECU is seeing values that range from 0.4 to 22 in less than 1 second.
In fact I disconnected the O2 gauge from the ECU and it was still getting the same signal. I even installed a new O2 sensor and got the same results.
Any thoughts on solving this?
What brand O2 controller? Innovates especially are really sensitive to issues with the sensor grounding.
That's the oxygen sensor itself. Microsquirt cannot read the low level voltage signal or run the heater so there is a controller in the middle (innovate lc1, 14point7 spartan, etc.) that handles that stuff. I'd bet your problem is in the ground wiring of that controller. Spurious noises signals doesn't seem like an O2 sensor element problem.
grounds...
rich
OK so I am no expert when it comes to chasing down where the electrical pixies go.
But for the Micro squirt, it uses a common ground for all of the sensors that feeds back into the ECU to prevent grounding problems. The coolant, intake air temp, MAP and O2 sensor all use the same ground.
These seem to be function correctly and that ground is internal to the ECU so there is no way to alter or improve the ground.
The O2 sensor is function correctly as indicated by the dash gauge and there was previously reasonable agreement between the ECU O2 reading and the gauge.
With the O2 sensor completely disconnected from the ECU it is still getting a signal that is exactly the same signal and wildly fluctuating reading that I see with it connected.
So this indicates to me there is something in the ECU that is not right.
Your O2 controller should NOT ground through the ECU. You're correct about the MS having a dedicated sensor ground. But the O2 sensor isn't technically a 'sensor' in this context, because the MS can't talk directly to the part in the exhaust, there is another controller that acts as an intermediary. That controller has it's own power and ground wires, but these aren't sensor power or ground. It's a subtle distinction, but important.
The O2 sensor controller is also powering a small heater element in the sensor. This takes a fair bit of power, and the ECU ground shouldn't have to deal with that much power.
The O2 controller should ground to the same place as the ECU grounds (Pins 22 & 23). Usually these ground to the engine case, but yours may be elsewhere.
a short in the ECU or aliens
Did you configure the microsquirt controller for and setup the AFR tables for a 0-5V input WBO2?
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