Internal combustion engines are typically tuned to operate under a variety of conditions. Factors such as engine performance and emissions control cannot always be set up for simultaneous optimal specifications, especially in light of the different conditions under which the engine must perform. For example, reducing undesired emissions usually requires sacrificing some degree of engine performance.
One of the factors to consider in engine operating setup is the emission of acceleration smoke, i.e., unburned fuel being exhausted during acceleration caused by a lag in air intake resulting in a rich fuel mixture for a brief period of time. Although the air/fuel ratio may be properly tuned during normal operations, the ratio momentarily becomes excessively rich during acceleration. The excess fuel does not all burn and emits through the exhaust system, thus resulting in a puff of white smoke.
Many attempts have been made to compensate for acceleration smoke. For example, in U.S. Pat. No. 4,372,268, Kolarik describes an apparatus which retards the increase in fuel flow during acceleration to reduce exhaust smoke. The apparatus described by Kolarik, however, is a mechanical structure which cannot be easily modified for varying operating conditions.
The advent of programmable controllers to perform many engine operating functions by the use of software programming has provided the means to be much more flexible in setting up an engine. For example, the amount of air and fuel to be delivered to an engine can be controlled electronically, thus allowing programmable control of the air/fuel ratio. For example, in U.S. Pat. No. 6,269,300, Moore-McKee et al. disclose a method by which software can be produced for engine controllers. Among the many applications of this software, maps can be created which control the air/fuel ratio under different operating conditions. For example, maps of engine speed, boost pressure, and fuel delivery amount can be created to control the air/fuel ratio to some degree.
These maps, however, are designed to accommodate a wide range of engines and operating conditions. Therefore, they must be programmed to a broad degree, i.e., to coarse settings, in order to be applicable to the many engines coming off the assembly line which are destined for many different uses. The coarse settings of the maps, by their very nature, prevent an operator from getting exactly the desired performance being sought from the engine.
The present invention is directed to overcoming one or more of the problems as set forth above.