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Re: 1991 crown vic 5.0 runs very rich
Posted to Technical Discussion Forum on 12/7/2009 2 Replies

Richard: Worn out (dead) 02 sensor sends out low/no signal & the PCM sees this as a lean signal & issues a rich command. Dead 02 sensor=lean 02 sensor signal=rich PCM command.

Fix what you know is wrong & see what happens.

David Login to read more.

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