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Impco Commander

Impco has an electronic feedback control system (Impco Commander Kit) to control the fuel mixture supplied to an engine by their mixers. The propane system is very similar to a conventional open-loop arrangement except for a few differences. The ADP system relies on an exhaust oxygen sensor to monitor whether the fuel mixture is rich or lean and tries to maintain a stoichiometric fuel ratio. A stoichiometric fuel mixture is one where there is exactly the right amount of oxygen to react completely with the fuel. That is, the fuel mixture is neither rich nor lean but ideal.

In addition to the exhaust oxygen sensor, a Commander system must obviously have the Commander electronic control unit (ECU), which ideally needs to be installed in the passenger compartment of the car. The Commander ECU receives the feedback signal from the exhaust O2 sensor and sends a control signal to the feedback converter. The converter is what actually provides the ideal fuel mixture to the engine. The converter does this by adjusting the fuel pressure supplied to the feedback mixer.

The feedback mixer is identical to the standard mixer except for the gas valve cone. The gas valve cone has a different shape than the standard mixer's gas valve cone. Impco would not say how it is different but from a control point of view, it would make sense for it to be shaped to supply a constant ratio of fuel to air. A standard mixer may be retrofitted with a feedback gas valve or a mixer may be ordered as a feedback mixer.

For you of you with ADP system (predecessor to the Commander), Impco was kind enough to provide us with the ADP installation manual in PDF form. As the manual is quite large, Impco has provided it in four parts and you may download it for yourself:

Raso Enterprises Digital Fuel Controller

Our Digital Fuel Controller is designed to work with air valve carburetion, such as IMPCO, Nolfe, OHG, or others. This product is only recommended for older carbureted vehicles (ie, pre-1987) and it works in a similar manner to the Impco ADP system. To convert newer vehicles, use an injection conversion instead.