Closing the Loop

It was going to happen eventually; closed-loop combustion control has finally been introduced to the
diesel world. Since the first electronically controlled diesel engines appeared in the mid-80s, diesels have been
required to operate in an open-loop environment. This was not a problem at the time, because it was relatively easy
to meet existing emission control standards without using feedback from the combustion process. These earlier
engines relied first on ECM calibrations and then catalysts to bring their emissions into compliance.