I was doing some research for the Chippernut Gauges and I came across Pete's Blog - and his OpenXC Tachometer for his Ford Fiesta. Very clean installation and unique application! The nice thing about this is it doesn't involve tapping wires or the risk associated with messing with the ECU. Just plug in the OBD adapter and go-to-town! Awesome!!!
Since turbocharging my IS300 this summer, I've been plagued with P0420 & P0430 codes -- Catalyst System below Efficiency. I tried simulating the output with my Innovate Wideband MTX-L, but after many months and configurations, I've given up. So I built a simulator based on a 555 Timer IC. I will install the new simulator tonight and report back w/ the results. Hopefully CEL free!
You can find the original schematics and instructions here.
R1 100 K Ohm
R2 1 M Ohm
R3 100 K Ohm
R4 10 K Ohm
C1 4.7 uF Electrolytic
C2 22 uF Electrolytic
D1 1.7v@20mA LED
D2 1.7v@20mA LED
This is meant to fool the ECU into thinking the post-cat O2 sensors are working and the catalyst is within spec.
IMPORTANT NOTE: If you build this, make sure you do not leave PIN 4 on the 555 timer open (floating). This will cause operation to stop and/or reset with even the slightest EMF or input voltage variation. Instead, connect PIN 4 to Input Power. I connected to PIN 8 and it works flawlessly.
The only other improvement would be a smoothing capacitor on the output - just to make the signal more of a SINE wave as opposed to the square wave.
Jon @ Chippernut