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The rich mixture should reduce HC emissions. Not increase it. High HC is the result of excessive combustion chamber temperatures. I would check EGR operation for that. The rich mixture you describe should produce a high CO.


I could be off on this.... But you may want to double check that, CO and HC would be up. If I remember right, NOx is high from excessive combustion temp.

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...