After working on the wiring of the primary O2 sensor for over three hours, and having four people looking at it, the issue remains. I still have the check-engine light and my K-Pro ECU still doesn’t recognise any AF ratio. Unfortunately, that means that I will have to spend more time and go through piece-by-piece to find the problem.

I’m thinking that the easiest way to go about the troubleshooting is to:

• Unhook the wiring from the ECU
  
• Use a multimeter to test the voltage of the 4 AFR-related pins at the ECU
  
• Reconnect the wiring to the ECU
  
• Test the voltage of those 4 wires before the relay
  
• Test the voltage after the relay
  
• Test the voltage right before the primary O2 sensor bung
  

At least this way I will be able to narrow the problem down to a specific location. If I don’t get any voltage in any one of the areas, that has to be the problem. I’m hoping that it is either broken wiring along the way, or that the relay is bad. Either of those two possibilities will be easy to remedy and very inexpensive. Anything else and I’m not sure what I will have to do.

Fortunately, Mike said he would come over and help me with all these steps sometime this upcoming weekend. With luck, we will have it done in just a couple hours.

|:| Zach |:|

Tomorrow I’m taking my car back in for some more work. We’re going to be uninstalling the AEM AFR gauge, and replacing it with the stock primary O2 sensor. That way, it can be wired directly into the K-Pro ECU, and will therefore, be datalogged with the rest of the sensors. This will also be nice for tuning. I also hope that we will be able to get to realigning the rear bumper (as it is slightly off on the driver’s side near the taillight).

Overall, I’m excited just to be getting the new O2 sensor wired up. It will be nice to see how the car runs with all sensors functioning properly. Changing the O2 sensor back to stock and wiring it into the K-Pro ECU has a good number of advantages:

• No more check-engine light (CEL).
  
• Most accurate reading of AFR.
  
• Auto-correction of improper AFR based on the loaded calibration.
  
• Ability to program in the various target-lambda values and have the K-Pro auto-adjust.
  

All that goodness just from swapping out one sensor! All of the AFR portions are incredibly beneficial because having a proper AFR reading will allow the K-Pro to dynamically adjust the injector flow. If it senses that the AFR is too lean, it will cause the injectors to fire harder and pump in more fuel. Contrapositively, if the AFR is too rich (like it currently is between 4000 and 5500 RPM at the VTEC point), the K-Pro will automatically reduce the injector duty to normalize back to the target lambda.

Hope all goes well. 🙂

|:| Zach |:|