failed california emission test on my 86 b2000. nox reading was 1522 and the max is 1120. the reading was at 15mph. i passed at the upper speed measuring 848 with the max at 1190. what to do to get this engine to pass? test results were @15mph co 13.3, o2 1.9, hc 43, co .02, and no 1522. resulkts @25 co 1, hc36, co .02 no 848. any clues or advice greatly needed!!! thanks again edsel...

Check the vacuum hose going to the EGR for cracks or leaks. If none, test the EGR with a hand vacuum pump, may have to take that off and clean it to restore its operation.

Slap another catalatic converter on there, that should fix the problem.

plus a new 02 sensor.

The EGR system lowers Nox. Your EGR valve is not opening or a passage including the valve as Cusser wrote is restricted (blocked) by carbon.