I am fairly certain codes are not generated on '87 models. The manual for Baum Tool's CS1000 scanner indicates they became available in '88 on California cars and in '90 on all U.S. cars. Still, you can look at the other three "windows" into your system, as explained by Steve B. in his article. Incidentally, an electronic dwell meter can be used to measure the duty-cycle of the oxygen sensor's square-wave output signal.