How do you reset the emissions to pass smog test?

Answer 1

Disconnecting the battery for a minute will reset the on board computer which in turn can cause a self calibration after the battery is reconnected and the engine is started. Whether that causes it to pass a smog test really depends if the computer actually needed to be reset. The probability is pretty low that reseting the computer alone will solve the problem; that is unless some other adjustment was made. For example when replacing a sensor or adjusting the ignition timing it can be good to reset the computer so it will recalibrate after the changes to the engine were made.

Here is a tip: the emissions will improve by retarding the timing. The allowed tolerance is +/- 3 degrees. Normally you set the timing to zero degrees with the computer disconnected. However, setting the timing to -3 degrees (retarded) is still within spec and can help it pass. You can get a timing light at Harbor Freight for $12.

Another tip: synthetic oil is supposed to be smokeless. It may help a little but dont expect a huge improvement.

Another tip: Premium gas is better when taking the test

General advice would be: fresh spark plugs, good spark plug wires, distributor cap and rotor. Make sure motor is fully warmed up first. Try to fix vacuum hose leaks if you can find them.