OBD II Drive Cycles & Trips

OBD II Drive Cycle'S & Trips
- A "Drive cycle" consists of engine startup and engine shutoff.
- "Trip" is defined as vehicle operation (following an engine-off period) of duration and driving style so that all components and systems2000 are monitored at least once by the diagnostic system except catalyst efficiency or evaporative system monitoring.

This definition is subject to the limitations that the manufacturer-defined trip monitoring conditions are all monitored at least once during the first engine start portion of the Federal Test Procedure (FTP).

- Within this text the term "customer driving cycle" will be used and is defined as engine start-up, operation of vehicle (dependent upon customer drive style) and engine shut-off.

Federal Test Procedure (FTP)
The Federal Test Procedure (FTP) is a specific driving cycle that is utilized by the EPA to test light duty vehicle emissions. As part of the procedure for a vehicle manufacturer to obtain emission certification for a particular model/engine family the manufacturer must demonstrate that the vehicle(s) can pass the FTP defined driving cycle two consecutive times while monitoring various components/systems.

Some of the components/systems must be monitored either once per driving cycle or continuously. Systems and their components required to be monitored once within one driving cycle:
- Oxygen Sensors
- Catalyst Efficiency
- Evaporative Vapor Recovery System

Due to the complexity involved in meeting the test criteria within the FTP defined driving cycle, all tests may not be completed within one "customer driving cycle". The test can be successfully completed within the FTP defined criteria, however customer driving styles may differ and therefore may not always monitor all involved components/systems in one "trip".

Components/systems required to be monitored continuously:
- Cylinder Misfire Detection
- Fuel system
- Oxygen Sensors
- All emissions related components/systems - EMS or EML (comprehensive component monitoring).

The graph shown is an example of the driving cycle that is used by MINI to complete the FTP.







The diagnostic routine shown above will be discontinued whenever:
- Engine speed exceeds 3000 RPM
- Large fluctuations in throttle angle
- Road speed exceeds 60 MPH

NOTE: The driving criteria shown can be completed within the FTP required ~11 miles in a controlled environment such as a dyno test or test track.

A "customer driving cycle" may vary according to traffic patterns, route selection and distance traveled, which may not allow the "diagnostic trip" to be fully completed each time the vehicle is operated.