Oxygen Sensors
This guide details the O2 sensor upgrade for my Honda RC51 custom ECU build, including specifications, connector details, and installation notes for the Jardine 2-1 full exhaust system.
O2 Sensors Overview
For my RC51 build, I upgraded to a Jardine 2-1 full exhaust system to boost performance. To enable precise air-fuel ratio monitoring with the FuelTech FT550 ECU, I had O2 sensor bungs welded onto the exhaust and opted for Bosch LSU 4.9 wideband sensors for their compatibility with the FuelTech WB-O2 Nano Pro. I also had the exhaust ceramic coated for durability and heat management.
O2 Sensor Specifications
The FuelTech WB-O2 Nano Pro supports several wideband O2 sensors, including Bosch LSU 4.2, 4.9, and 5.2. I chose the LSU 4.9 for its reliability, fast response time, and widespread use in performance applications. These sensors measure oxygen content in the exhaust, providing real-time data to the ECU for fuel mapping adjustments.
| Sensor Type | Description |
|---|---|
| Bosch LSU 4.2 | Improved version with better durability, compatible with WB-O2 Nano Pro. |
| Bosch LSU 4.9 | Modern model, fast response, high accuracy, used in this build. |
| Bosch LSU 5.2 | Advanced wideband sensor with enhanced precision and robustness, compatible with WB-O2 Nano Pro. |
Connector Specifications
I purchased a harness for the WB-O2 Nano Pro from FuelTech, which came pre-terminated with the appropriate connector for the Bosch LSU 4.9. This connector can be sourced here.
| Connector Type | Part Number | Description |
|---|---|---|
| FuelTech Harness | 2001010315 | Pre-terminated harness for Bosch LSU 4.9 integration with WB-O2 Nano Pro. |
Refer to the ECU Harness documentation for wiring details. Ensure proper placement of O2 sensor bungs for accurate readings, as shown in the image gallery below.
Jardine 2-1 Exhaust and Bung Installation
The Jardine 2-1 full exhaust system required welding O2 sensor bungs to accommodate the Bosch LSU 4.9 sensors. Since the RC51 has two cylinders, I installed an O2 sensor for each cylinder to monitor individual performance. However, a single sensor would work as well, post collector. The rear header’s O2 sensor bung was placed closer to the head than ideal due to space constraints. I’ll monitor the sensor’s longevity in this position.
O2 Sensor Images
Explore this collection of images showcasing the O2 sensor bungs welded onto the Jardine 2-1 exhaust system and the installed Bosch LSU 4.9 sensors.
