I recently saw a video of a guy doing a pull in his turbo Civic si and the tachometer was his air fuel gauge (5000 rpm = 15:1, 2000 rpm = 12:1 etc). I think he used a standalone ECU that let him do that but I thought it was super cool. I wanted to make a cheap device that can just take the analog output from a wideband gauge stuffed behind the dash and send it to the tach. Ideally it would be switchable with a steering wheel button for when you want your actual RPM to display again. Question: do the civics use a square wave signal or an analog voltage signal to tell the tach where to go? If they do use a square wave, is each pulse one revolution, one pulse per two revolutions, or two pulses per revolution? I don't have an oscilloscope to measure but maybe I'll get one soon. Obviously if you have a wideband with an analog out then you don't need a tach to be your AFR gauge but I think it just looks cleaner without an extra gauge. If anyone has ideas or someone knows an easier way to do this then let me know. Thanks.

 

They were running Hondata Flashpro.

Gauge cluster is fully CAN bus. To interrupt the tach signal you would need a CAN firewall between the gauge cluster and the rest of the CAN network to intercept the CAN signal for the tach and then modify it.

Or just go to Hondata or run a scan tool or scan gauge or any of the other OBD port displays.

 

sweet thanks