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Emission Test Driving Schedules for Dynamometer Testing: SAE J1506 Guide
Overview of Dynamometer Driving Schedules
This SAE Information Report (J1506) describes various dynamometer driving schedules used globally for measuring exhaust emissions and fuel economy of passenger cars and light trucks. The document includes descriptions and second-by-second speed-time sequences for schedules like the U.S. 1972 (UDDS), 505, FTP, HWFET, ECE R15.04, Japanese 10-mode, and 11-mode. These schedules simulate real-world driving conditions for certification, development, and compliance testing.
Key Schedules and Their Characteristics
| Schedule | Duration (s) | Distance (km) | Avg Speed (km/h) | Application |
|---|---|---|---|---|
| U.S. 1972 (UDDS) | 1372 | 12.1 | 31.46 | Base for many U.S. cycles |
| 505 Schedule | 505 | 5.78 | 41.2 | Hot start emissions testing |
| 1975 FTP | 1877 (incl. hot soak) | 17.77 (approx) | 34.1 | U.S. certification |
| HWFET | 765 per cycle | 16.4 per cycle | 78.2 | Highway fuel economy |
| ECE R15.04 | 195 per run | 4.06 (manual) | 18.7 | European certification |
| Japanese 10-Mode | 135 per run | 0.664 per run | 18 | Japanese warm start |
| Japanese 11-Mode | 120 per run | 1.02 per run | 30.6 | Japanese cold start |
Note: The FTP includes a 10-minute hot soak period. Japanese 10-mode is run six times but emissions sampled only during the last five. Japanese 11-mode is run four times from cold start.
Engineering Design Insights and Common Mistakes 🛠️
Design Insight: Driving schedules are carefully crafted to represent typical urban and highway driving patterns. The U.S. 1972 schedule (UDDS) serves as the foundation for many others, such as the 505 and the full FTP. The inclusion of hot soak periods in the FTP and 505 schedule simulates real-world engine restart conditions, providing more realistic emission measurements. The diversity of international schedules reflects regional driving conditions and regulatory requirements.
⚠️ Common Mistakes:
- Using the incorrect driving schedule for a specific regulatory certification (e.g., UDDS instead of FTP for US certification).
- Not accounting for necessary preconditioning such as hot soak or warm-up cycles before emission measurement.
- Misinterpreting speed units (mph vs km/h) or not following the precise second-by-second speed trace from the tables.
- Failing to run the correct number of repetitions (e.g., Japanese 10-mode requires six runs, but emissions are sampled only during the last five).
- Applying a schedule designed for passenger cars to heavy-duty vehicles without modification.
Frequently Asked Questions (FAQs)
What is the purpose of the hot soak period?
The hot soak period, typically 10 minutes with the engine off and hood closed, simulates a vehicle restart after a short stop. This allows measurement of emissions during hot start conditions, which can differ significantly from cold start levels.
How are driving schedules used for fuel economy testing?
Schedules like the Highway Fuel Economy Test (HWFET) are designed to represent high-speed driving conditions. Fuel consumption is measured over a standardized cycle, and the results are used to calculate official highway fuel economy figures.
Why are there multiple repetitions in the Japanese 10-mode test?
The first run stabilizes the vehicle and catalyst. Emissions are collected only during the last five runs to ensure consistent, repeatable measurements under fully warmed-up conditions.
What are the consequences of using an incorrect schedule?
Using the wrong schedule can lead to invalid certification results, failed tests, or misinterpretation of emissions data. It can also waste time and resources if the test must be repeated. Always verify the specific requirements of the governing regulation.
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