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Automotive Emissions and Onboard Diagnostics

by John West & Mark Stachew

Start ý Why Onboard Diagnostics? ý Major Components ý Catalytic Converter ý Oxygen Sensor ý EGR ý Fuel System Adaptive Learning ý Misfire Detection ý The Need for Speed ý New Regulations ý 0 to 100 KB in 6 Seconds ý Sources and PDF

NEW REGULATIONS

What will future regulations bring? Well, reducing emissions is like a limbo contest, where the real question is, "How low can you go?" Future regulations will concentrate more on the reporting mechanism rather than emission output reduction. OBD II is a great step in controlling and monitoring emission systems, but it does not help in reporting the problem. OBD II turns on the MIL light, but itýs up to the vehicleýs owner to bring the vehicle in for service and possibly a hefty bill. Because emission-related failures often donýt affect how the car drives, there is little incentive for owners to have repairs done.

Using radio transponder technology, a future OBD-equipped vehicle would be able to report emissions problems directly to a government agency. The transponder would communicate the vehicle identification number and any fault codes that were present. The system could be set up to automatically report an emissions problem via a cellular or satellite link the instant the MIL light comes on. With remote monitoring via the onboard telemetry, the need for periodic inspections could be eliminated because only those vehicles that reported problems would have to be tested.

In addition to improved failure reporting mechanisms, the future will bring increasingly stringent emissions requirements. Misfire detection will be required over the full range of engine operation. Electronic throttle control (ETC) may become an OBD standard. ETC allows more precise fuel control but requires more complex algorithms and increased CPU bandwidth.

Reliability requirements are likely to increase from the current 10 year/100k miles to 15 years/150k miles. Diagnosing failures after their occurrence will no longer be adequate. Engine management systems will be required to predict failures based on the performance trends of a component or system.

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