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.

SALE on now, Save 50% off your Cobb Protune with purchase of Cobb AccessPort for EVO X

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, if you don’t already have one pick one up with the link below for the best pricing guaranteed.

AEM X-Series Wideband (AFR gauge/sensor kit)

Original price was: $196.65.Current price is: $179.00.

The X-Series Wideband UEGO AFR Gauge delivers easy to use wideband AFR data via gauge display as well as analog output 0-5 volt and CANbus. The X Series AFR gauge features a user configurable display via buttons on the gauge face that allow you to change AFR values for different fuels, Lambda or O2%, change…

SKU: 30-0300
Category: ,

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.

Etune: Check out the full Etune write up for details, pictures and video! Brewed Tuned Etune and Dyno tuning and the link for Cobb AccessPort dyno tuning or Etune services.

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.

evo x wideband afr wiring seat plug

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.

evo X rear o2 wideband wiring
evo X rear o2 wideband

*****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).

cobb AP gauge display data log

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 

7 thoughts on “EVO X & Ralliart wideband AFR logging Cobb AccessPort

  1. Eligio says:

    So I did hook my wb to the rear 02 as instructed. And it works!. So how do I get my engine light off? AEM Wb with its .5 v is triggering the .1 v of the narrow band a CEL. Is this able to be removed with accestuner? Thank you in advance.l

    • Eric_Brewed says:

      if you connected the 0-5v to the rear o2 sensor harness so you can log the AEM wideband the easiest way to keep the ECU happy is to wire in a switch so you choose between stock rear o2 and AEM wide band o2. Depending on the car and which rear o2 sensor code is thrown there is unfortunately no way to always remove the code. The switch set up will allow you to log with the AEM and then easily go back to stock o2 so the ECU doesn’t throw a code. ***not all EVO X’s will throw a code, but if you do the switch will be the easiest way to work around it.

  2. Matt blunk says:

    I’ve been banging my head on the wall with this. I installed the gauge and sensor fine, works great. I T’d into pin 3 on the O2 connector. (Which is orange on my car, but clearly marked pin 3) but I get no reading at all on the accesport. There’s only 1 white wire to connect to, so don’t think I can screw that up. Any advice? I do have the ego X series, I read somewhere that they won’t work, I’ve also read they do. Idk….but my cars getting tuned in 3 days and this is a problem. Thx

    • Eric_Brewed says:

      Hey Matt, we use the AEM X series wide band wired into the rear o2 sensor all the time and no problem at all on the EVO X using Cobb AP. You must either have your wiring wrong or you are not monitoring the correct parameter on the AP.
      **Just a heads up if you would have purchased your AEM wideband o2, Tune or Cobb AP through us our tech support team is always available to support ALL of our customer every step of the way with any products or services we offer via email, or direct phone/video chat!**

      if you are not familiar with wiring or setting up the rear o2 sensor i would suggest letting a professional do it for you. Anyone that tunes the Cobb AP for the EVO X application should be able to wire up and start logging a wide band o2 sensor via “rear o2 voltage” in about 30-45 min including removing the passenger seat.

  3. Declan says:

    On my 2015 Evo there is no yellow wire to splice into on the D35 plug connector. Due to space constraints I found it easiest to cut off the O2 sensor plug and wire the yellow “analog signal out” on the LC2 to the blue wire on the cut O2 sensor harness (green on D35) and the black ground wire on the LC2 to the white wire on the O2 sensor harness (red on D35) which I then grounded under the seat. The two black wires on the sensor harness are the heater circuit and are not needed. No CELs with this method

  4. Declan says:

    I take back what I said about no CEL; ended up getting a P2252 which disables the front o2 sensor LTFT. I ended up having to unground the rear 02 sensor harness and adjust the output of the LC2 to try and fix the offset.

    • Eric_Brewed says:

      Be careful, without a proper sensor ground circuit you can introduce a lot of issues into the signal. You may get the AFR data to match up for a short time by adjusting the offset/scaling BUT you will likely see the values drift again after a short time do to other variables in the electric system.
      We recommend ONLY using the rear o2 harness to datalog wideband AFR data while on the dyno or on the race track for testing/logging/racing. We do NOT recommend modifying the rear o2 sensor or harness for the a normal use vehicle.

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