Depends where you are. If yours went through the DOT/EPA wringer, it's got some sort of O2-sensor based mixture control.

The ECU I've got is located behind the false firewall to the right of the ABS controller; and I don't have an EHA valve, so I'm not really sure what's being controlled besides the little bypass line.

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A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.