The Fiero's electro/pneumatic EGR system is prone to problems in part due to age, and reliable EGR solenoids are hard to come by. They aren't made any more, though some later versions can be modified to work on the Fiero. The digital valves are/were widely used on GM cars. The Fiero system consists of 2 parts. The solenoid and the valve. The digital EGR combines both into one and is efficiently controlled by the superior 7730 ECM.