The Air Resources Board, with the aid of the California Highway Patrol and the Bureau of Automotive Repair, will be conducting roadside checks in Ventura County during the week of April 29, as part of a statewide study of anti-smog system tampering and the success of the state's Smog Check Program. 

The roadside checks which began last month in Los Angeles on the eve of the Smog Check Program's first anniversary, are intended to help researchers understand how well California cars are maintained, the extent to which anti-smog systems are ta1npered with, and how much leaded fuel is illegally used in newer catalytic converter-equipped cars. 

Ventura is the fourth stop tor the roadside checks after Los Angeles, the San Francisco Bay Area and Sacramento with future stops scheduled for Fresno ana San Diego through the end of May. 

ARB Chairman Gordon Duffy emphasized that the tests, which can be done in 20 minutes, are purely for research purposes and that no citations will be issued tor illegal engine modifications. He also explained that the tests may provide clues about the effectiveness of the state's Smog Check program, which began once-every-two-year inspections of automotive anti-smog systems last March. 

"Since the program is now a year old, about half of all cars in the state's urban areas have gone through the inspections", Duffy explained. These roadside tests may tell us whether cars that have already gone through the Smog Check comply with the state's anti-smog laws better than cars that will be tested in the next year". 

"These tests also are part of our ongoing research program to study the durability of anti-smog systems and the maintenance habits of California car owners," Duffy said. 

Cars participating in the tests will be selected at random and directed to inspection lanes set up on the side of major streets. The test will include an under-the-hood inspection of anti-smog controls and tailpipe readings of pollutants at idle and at 2500 rpm. 1975 and newer cars, which are factory-equipped with catalytic converters, will have fuel samples taken and a tailpipe test to determine if they have been illegally fueled with leaded gasoline. 

Motorists flagged down for the test will be given a check list showing the condition of their car's pollution control system. Duffy said the check lists "could provide car owners with clues to poor driving performance or low gas mileage caused by faulty maintenance or tampering with anti-smog controls." 

"Motorists who tamper with anti-smog systems, in the mistaken belief they can improve a car's performance, actually cause the very problems they think they're trying to solve," Duffy said, "especially on newer cars, which are run by computers that constantly tune the car while it's being driven."

Preliminary results of the state's Smog Check program, which has tested about 3.5 million cars since last March 19, show that about one-third of all cars fail the test. Emissions of smog-forming hydrocarbons and carbon monoxide, however, are reduced by about 50 percent with low-cost repairs of adjustments. 

Random roadside tests conducted by the Air Resources Board in 1983 showed about 68 percent of the cars complying with anti-smog laws. Eighteen percent of cars tested in 1983 were found to have one or more of the smog control systems not working properly and another 14 percent showed signs of tampering or illegal removal of emissions control equipment.