EGR distribution and fluctuation probe based on CO2 measurements

A diagnostic system comprising:

• a signal light source producing light in a first portion of the MIR spectrum, said first portion including CO2 absorption features;
• a reference light source producing light in a second portion of the MIR spectrum, said second portion not including substantial CO2 absorption features;
• a beam combiner disposed adjacent to said signal light source and said reference light source to produce a combined light beam;
• a detector for producing measurements representative of a light beam;
• and
• a probe including:
• a single port housing;
• a sampling chamber defined within said housing;
• a pitch optical cable disposed within said housing, said pitch optical cable conveying said combined light beam from said beam combiner to said sampling chamber;
• a catch optical cable disposed within said housing, said catch optical cable conveying said combined light beam from said sampling chamber to said detector;
• a mirror disposed adjacent said sampling chamber for reflecting said combined light beam to said catch optical cable.

A method for quantifying EGR fluctuations, comprising the steps of:

• providing an EGR probe in which pitch and catch optical paths are included in a single housing suitable for mounting within a single port;
• producing a signal light beam and a reference light beam over different spectra;
• combining the signal and reference light beams into a combined light beam;
• directing the combined light beam in a first direction through the housing via a pitch cable;
• passing the combined light beam from the pitch cable through a fluid stream to be measured;
• reflecting the combined light toward a catch cable;
• directing the reflected beam through the housing in a direction opposite to the first direction via a catch cable;
• receiving the light beam at a detector;
• and
• determining with a processor the concentration of a component within an intake or exhaust manifold as a function of the detected light beam.