O2 Input 0-5v Modification


Posted on Feb 5, 2014

Software such as that available on PGM-Fi. org and from Hondata make use of the Honda ECU`s oxygen sensor input to allow real time display and data logging of wideband oxygen sensors. This involves feeding the analogue output of the wideband sensor`s controller in through the stock (narrowband) O2 input. The known relationship of voltage to AFR is


O2 Input 0-5v Modification
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then entered into the software package you are using to allow it to log a real world value. The wideband set-up I purchased a while ago from Innovate Motorsports features two independent programmable outputs with a maximum 5v range of operation. This allows you to set each output to supply a voltage of 0-5v in almost any linear relationship to AFR in the controller`s operating range, typically 10:1-20:1 AFR. The most logical way to configure the unit would be 0v for 10:1 and 5v for 20:1, but there is a limitation with the stock ECU that prevents us from doing this. The stock Honda O2 sensor input will only read to a maximum of around 3. 8v, this does not present any problem when the stock narrowband O2 sensor is used as hovers about the 1v area in operation. While you could just configure your WB controller to output from 0-3. 8v from 10:1 to 20:1 AFR, it would be a lot more accurate if you could read to 5 volts. Another problem is that many WB O2 controllers (like the AEM, TechEdge etc) do not allow you to alter the wideband signal output - this means any AFR above the 3. 8v threshold will not be read! Various people in the past have used op-amps to rescale the 0-5v output of these wideband controllers to meet the restraints of the ECU, and while it gets the job done it would be nice to have everything done properly. To get around this limitation I started tracing the input stage to for the O2 sensor input, as most other...




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