State-of-the-art fuel injectors can be defined by a third-order polynomial
to define their performance curve and to optimize performance of the fuel
injected engine. Such systems are preprogrammed to use a set of fixed
coefficients when replacing fuel injectors. Therefore, these replacement
fuel injectors must be manufactured with very precise tolerances so as to
operate efficiently with these fixed coefficients. The present invention
includes a method and apparatus that allows the use of production fuel
injectors that are more economical since they can be manufactured with
wider tolerances. The production fuel injectors are supplied with a
computer program and a data file having a set of replacement coefficients
that are determined especially for that particular fuel injector. The
approach allows the restoration of the existing coefficients if the
replacement fuel injector does not solve the service problem experienced
by the user of the fuel injected engine. The new, replacement fuel
injector, together with its specific coefficients, can then be used in
another application.