Cold Start Noise Reduction

Cold Start Noise Reduction Explained

The Cold Start Noise Reduction calibration disables or softens the ECU cold-start routine that normally enriches fueling, raises idle RPM, and adjusts ignition timing while lambda sensors warm up. That process speeds up catalyst heating but often produces a loud exhaust note and rough idle for 30–90 seconds. By refining those start-up strategies at software level—no hardware changes required—the engine starts quietly and smoothly, ideal for tuned cars or residential environments.

Modern ECUs run multiple concurrent subroutines during cold start: open-loop enrichment, idle-air torque requests, spark retard for catalyst light-off, and sometimes secondary-air injection. Cold Start Noise Reduction carefully adjusts those maps and limiters to eliminate unnecessary noise while preserving reliability and drivability once warm.

Read more about cold start behavior on Wikipedia – Cold start (engine).

When to Use

• After installing a sport or decat exhaust and wanting a quieter morning start-up.
• When OEM calibration causes aggressive idle flare or vibration on startup.
• To reduce exhaust drone in enclosed or residential areas.
• On tuned petrol engines where stock warm-up maps are overly rich.

Technical Details

Cold start control relies on several subsystems:

• Fuel enrichment tables controlling mixture vs. coolant temperature and time since start.
• Idle speed targets and torque adders to stabilize combustion with a rich mixture.
• Ignition retard strategies used to heat catalysts quickly but increase noise.
• Secondary-air injection activation affecting AFR and sound signature.

This calibration trims fueling and idle targets during the first warm-up phase, optimizes related limiters, and re-aligns ignition and torque requests. The result: quieter, smoother startups without affecting warm-engine operation. It integrates well with other comfort and sound-management solutions like Exhaust Flap Removal and Sport Displays Calibration.

How It Works

1. Assessment: We analyze your current calibration and logs to measure cold-start intensity.
2. Calibration: We prepare a Cold Start Noise Reduction file optimizing fueling, idle, and timing.
3. Flash & Verify: Flash the file with your tool and confirm smoother, quieter startup operation.

Compatibility & Tooling

Supported for most petrol ECUs with controlled cold-start enrichment. Use the live database below to check compatibility. If your ECU or ID is missing, send us your read file and we’ll add support.