To reduce NOx on my '85, I found retarding the ignition timing a few degrees helped, as did running a tank of premium gas (for the test). Also spent a day cleaning and porting out the EGR passages in my header and head plus the EGR plumbing and valve. My EGR would kill the engine with the simple vacuum test, but it seemed that there was not enough flow at the higher engine loads to be effective.

r.c.brown@ieee.org
TruckEditor@tlca.org
Project: 4Crawler
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