Evo X and Ralliart Wideband AFR set up and wiring Cobb AP
AccessPort: A hand held tuning, data logging and display used for ECU tuning.
AFR: Air Fuel Ratio, this is the ratio of air vs fuel during combustion in your engine. (A key part of tuning).
Don’t have a wideband o2 gauge yet? The AEM X series AFR gauge are highly recommended for easy logging through your AP. We have used this wideband on hundreds of cars all with great success.
Data Log: a recording of engine and or chassis sensor data used to diagnose, tune or trouble shoot an EFI engine, suspension or chassis set up. Check out our https://brewedmotors.com/blog/evo-x-ralliart-cobb-accessport-data-logging EVO X how to Data Log post to learn how to take logs, review logs and understand exactly what you are looking at.
Logging wideband AFR data while tuning an EVO X is a must! Here is a simple and easy solution for all EVO X & Ralliart owners using the Cobb AccessPort with an AEM or Innovate wide band o2 gauge. In a nut shell we are taking the 0-5 volt wideband AFR data and wiring it to the factory ECU input that was originally used for the rear o2 sensor signal. (The rear o2 sensor signal/data is not helpful while tuning so we replace this with the VERY useful wideband AFR data).
The Rear O2 sensor wiring is routed through a grommet under the right hand seat/under a small flap in the carpet. You can easily access the wiring with the seat still bolted down but to get in splice the wiring you may need to unbolt the seat and move it back out of the way an extra few inches.
Identify the D-35 connector (4 pins) see image below. Unclip the connector from the floor and disconnect the rear o2 sensor. If you are leaving the factory rear o2 sensor in the car simply tuck the plug safely back under the carpet. If you are removing the rear 02 push the wiring/plug through the grommet on the floor.
*****WIRE COLOR MAY CHANGE, use D35 connector pin out above****
D35 4 pin connector: Pin 3 is the available “Input” to the ECU (yellow wire on most USDM EVO’s) This is the wire the 0-5 Volt signal from your Wideband O2 needs to connect to. T into the yellow wire, using a good clean connection!
**problems with this wiring/connection will cause false AFR readings.**
D35 4 pin connector: Pin 4 (orange wire on most USDM EVO’s) should be grounded to the exact same point as the Wideband AFR gauge/controller. T into the orange wire, using a good clean connection! **problems with this wiring/connection will cause false AFR readings.** This ground ensures a clean non offset signal at the ECU.
Key on AccessPort connect to the car go into the data logging parameters list on your AccessPort and select the correct WB afr option to match your Wideband gauge, IE: AEM or Innovate.
Take a data log (as requested by your tuner!) and email it. You can also open your log and look through the data yourself to get an idea of how your car is running. EVO X DIY Data log and review blog.
**NOTE** PLEASE refer to the install instructions for your specific Wideband AFR gauge/controller to find the 0-5 Volt output and the sensor ground/signal ground. Log parameter “rear 02 volts” This will display as a 0-5 volt value that we use in our data analysis software to calculate the wideband AFR data. We implement the exact same strategy for Open Source tuning as well the only difference being the 0-5 volt signal is calculated to AFR in the Open Source software VS the data analysis software. (Both options work great and result in the same data).
Special thanks to xPRimNT of evoM forums for the same write up when using open ECU and the great pictures! EVO X data logging Wideband O2, AFR data