Guys, I have just installed my dual channel FJO wideband this weekend, and am getting some strange results. I have posted a screenshot of my problems below. Basically, during prolonged idle (only a few seconds), the sensor feedback becomes erratic. The sensor (NTK) jumps from way rich to way lean in a split second.

It should be noted that this is with an Open Loop engine calibration; Fuel Pulse widths are dead constant while the O2 readings are doing this. I know it appears like the rapid rich/lean you would see during closed loop operation with a narrowband, but I have verified that it is not this.

This unsteady signal is produced by BOTH the digital output to datalogging software, and the Analog outputs, which I can log through the engine control module. You can see that during a brief few seconds (about 1/3 of the way into the trace), that the signal stabilized to what I would consider “normal”. I have previously been using the older FJO single channel controller, and that is what it is supposed to look like, ie., relatively small less than ˝ point fluctuations.

I have tried to disconnect the analog outputs to ensure there is no interference from my engine control module. That did not change the results. Interestingly, when zooming in on the problem areas, the Peaks and Valleys produced are identical on the left and right channels, this would lead me to suspect the controller. I will attach the data file as well.

This condition seems to go away when cruising, and the sensor readings become normal and steady.

Perhaps the sensors are not hot enough at idle to maintain proper readings? Could it be electrical interference? Bad ground? I am really lost as to what might be wrong. FJO tech support has not returned my email.

I appreciate any advice you can provide.

Todd

 

Are you connected directly to the battery? I'd recommend it, if you're not. I've seen similar noise when using a cigarette lighter socket on an LM1, or even when using a 110V converter to power a laptop.