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Re: 91 chevy 4.3 high CO...help....
Posted to Emissions Forum on 3/23/2005

What type of EGR system is used on this vehicle? Some of the negative backpressure EGR valves have a tendency to open too much, too early and cause a subtle "EGR bog" resulting in low power and an upset fuel mixture. Try unplugging the EGR as a quick diagnosti... Login to read more.