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OBD-II PIDs (On-board diagnostics Parameter IDs) are codes used to request data from a vehicle, used as a diagnostic tool. SAE standard J1979 defines many OBD-II PIDs. All on-road vehicles and trucks sold in North America are required to support a subset of these codes, primarily for state mandated emissions inspections .
OBD-II is an improvement over OBD-I in both capability and standardization. The OBD-II standard specifies the type of diagnostic connector and its pinout, the electrical signalling protocols available, and the messaging format. It also provides a candidate list of vehicle parameters to monitor along with how to encode the data for each.
A driving cycle is a series of data points representing the speed of a vehicle versus time. Driving cycles are produced by different countries and organizations to assess the performance of vehicles in various ways, for example, fuel consumption, electric vehicle autonomy and polluting emissions.
EPA HWFET driving cycle. The "highway" program or Highway Fuel Economy Driving Schedule (HWFET) is defined in 40 CFR 600.I. [10] It uses a warmed-up engine and makes no stops, averaging 48 mph (77 km/h) with a top speed of 60 mph (97 km/h) over a 10-mile (16 km) distance. The following are some characteristic parameters of the cycle:
The data is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion (see stoichiometry) and influence the advance or retard of ignition timing. A fuel-injected engine may alternatively use a mass airflow sensor (MAF sensor) to detect the intake airflow.
For example, the vehicle computer can identify past driving history as one particular representative cycle (say, FTP-75) and use known information from FTP-75 to improve vehicle performance. This type of control strategy is most useful for hybrid vehicles where the control strategy has a much greater effect on vehicle performance than with a ...
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One driving force behind this is the increasing adoption of the engine Electronic Control Unit (ECU), which provides one method of controlling exhaust gas emissions within US and European standards. The telematics data is used (via Fleet Telematics Systems ) by Fleet Management Systems to let fleet operators keep track of vehicle and driver ...