Research Projects

Project at a Glance

Project Status: complete

Title: Characteristics and impact of electronic automotive emission control systems

Principal Investigator / Author(s): Carlson, Richard R.

Contractor: Systems Control, Inc.

Contract Number: a0-144-32

Research Program Area: Emissions Monitoring & Control

Topic Areas: Impacts, Mobile Sources & Fuels


A test program was conducted using ten 1981 or 1982 model year vehicles equipped with state-of-the-art closed loop-electronic emission control systems (EECS). The purpose of the test program included determining the effect of disconnecting or disabling selected components of the electronic control system and whether the disconnected / disabled components could be detected during field repairs. Tests performed included the U.S. Environmental Protection Agency's (EPA) 1975 Federal Test Procedure (FTP) and Highway Fuel Economy Test (HFET); and a steady state test and driveability test specified by the California Air Resources Board(CARB). At least ten disablements were induced in each vehicle. One disablement for each vehicle was implanted before the vehicle was sent for diagnosis and repair. The test program showed that the impact of disabling components upon emissions, fuel economy and driveability ranged from negligible to dramatic, depending on the component and system. Closed-loop systems which incorporated on-board diagnostic and driver warning systems provided better detection of disablements than systems without on-board diagnostics and were more likely to result in correct diagnosis and repair of the vehicle.


For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893

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