Performing a throttle body relearn on a Nissan 350z is crucial after disconnecting the battery, throttle body, or related components. This procedure allows the car’s computer, or Engine Control Module (ECM), to relearn the idle position and closed position of the throttle plate. While a scan tool can be helpful in diagnosing related issues, it’s not always necessary for the relearn process itself. This article outlines the procedures for performing a throttle body relearn on a 350z, both with and without a specialized scan tool.
Understanding Throttle Body Relearn on a 350z
The 350z utilizes an electronic throttle control system. When components are disconnected, the ECM loses its learned parameters for the throttle body. A relearn procedure helps restore these settings, ensuring proper idle speed, throttle response, and overall engine performance. There are three key learning procedures:
Accelerator Pedal Released Position Learning
This procedure teaches the ECM the position of the accelerator pedal when fully released. It’s essential to perform this step first. The process involves turning the ignition ON and OFF in a specific sequence, allowing the ECM to calibrate the accelerator pedal position sensor.
Throttle Valve Closed Position Learning
This step teaches the ECM the position of the throttle valve when fully closed. The procedure requires turning the ignition ON and OFF, allowing the ECM to register the throttle position sensor signal at the closed throttle position. You should hear the throttle body motor actuate during this process.
Idle Air Volume Learning
This procedure allows the ECM to learn the correct amount of air required to maintain a stable idle. This process is more complex and requires specific conditions to be met:
- Battery Voltage: Above 12.9V
- Engine Coolant Temperature: 70-100°C (158-212°F)
- Park/Neutral Position Switch: ON
- Electrical Loads: OFF (A/C, headlights, rear defogger)
- Steering Wheel: Straight ahead
- Vehicle Speed: Stopped
- Transmission: Warmed up (specific procedures for automatic and manual transmissions apply)
Performing the Relearn Procedures
With a Scan Tool (CONSULT-II)
A CONSULT-II scan tool, Nissan’s specialized diagnostic equipment, can simplify the Idle Air Volume Learning process. After performing the Accelerator Pedal Released and Throttle Valve Closed Position Learning procedures manually, the CONSULT-II can initiate the Idle Air Volume Learning automatically. The tool guides you through the process and confirms completion.
Without a Scan Tool
The 350z allows for a manual relearn procedure without a scan tool. After completing the first two learning procedures, a specific sequence of accelerator pedal presses and holds, combined with timed ignition cycles, allows the ECM to relearn the idle air volume. This manual method requires careful timing and adherence to the specific steps outlined in the vehicle’s service manual.
Conclusion
While a scan tool like the CONSULT-II can streamline the Idle Air Volume Learning process on a 350z, it’s not essential for performing a throttle body relearn. The manual method, while requiring precise timing and execution, can be effectively used to relearn the throttle body. Understanding and correctly performing these procedures are crucial for ensuring optimal engine performance after working on the throttle body or related components. Always consult your vehicle’s service manual for the most accurate and up-to-date instructions. If you’re uncomfortable performing these procedures yourself, consult a qualified mechanic.
