It has to perform a series of self tests on the emissions systems. That is called a "drive cycle" and can include such things as a brief burst of rapid acceleration, prolonged steady speed on the highway without touching the brake pedal, and various things like that. Some cars even require driving for a certain number of miles with a full gas tank and again with it near empty to gauge whether there is a leak in the evaporative emissions system. Only Chrysler uses a leak detection pump to put their systems into 2 pounds of pressure. GM pumps theirs into a vacuum, then watches for a leak. The tank gets sucked into a vacuum anyhow while driving and using up some gas. When all of the right conditions are met for the self tests to run, the inspection place will connect a computer and see that those tests were passed and you'll be done. Many testing stations will still run the manual set of tests just like they do on the '95 and older models that don't have that self test capability. On some cars it can be very frustrating to get them to do their self tests so the inspectors make that allowance. If your guys are hard-nosed and lack common sense or a cooperative spirit, you'll just have to keep driving until the self tests run and pass.
Mar 26, 2011 at 8:33 PM
