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DESCRIPTION AND OPERATION
GLOSSARY OF TERMS
Active Regeneration
Cleaning a diesel particulate filter using an
auxiliary heating mechanism to achieve optimum
temperature for rapidly inducing chemical
changes in the particulate matter trapped in the
filter.
Air Pressure Sensor
The air pressure sensor is mounted in the air
intake between the CMCAC outlet and the EGR
mixer. This sensor monitors CMCAC outlet
pressure and relays this value to the EECU
module.
Ash
The noncombustible portion of diesel particulate
matter. Diesel fuel produces little ash, but
crankcase lubricant and fuel-borne catalysts
produce considerable ash.
Atmospheric Pressure Sensor
A sensor incorporated into the EECU that detects
atmospheric (barometric) pressure. This pressure
is affected by altitude.
Carbon Monoxide (CO)
An odorless, colorless gas resulting from
incomplete combustion of hydrocarbons; found in
diesel truck exhaust; poisonous to humans and
animals.
Catalyst
A substance that promotes or provokes chemical
change at a different rate or different temperature
than otherwise possible.
Cooled Exhaust Gas Recirculation (CEGR)
A system whereby a pre-determined amount of
exhaust gas is diverted through a heat exchanger
where it is cooled and sent to the inlet manifold
for reintroduction into the combustion chambers.
Adding the cooled exhaust gases to the
combustible fuel and air mixture lowers the
overall combustion temperatures for reduced
formation of nitrogen oxides (NOx).
Cordierite
A ceramic material constructed to be used as a
substrate in diesel oxidation catalysts. With
additional processing, it may also be used as a
diesel particulate filter.
Diesel Particulate Matter
The complex mixture of extremely fine particles
and liquid droplets that are discharged by an
operating diesel engine. The chemical
compositions can be broken down to safer
substances. The mixture is also called soot and
ash.
Differential Pressure Sensors
These are devices designed to read air (gas)
pressure at two points in the path of the flow and
report the values for use in algorithms in the
EECU.
Discharge Recirculation Valve (DRV)
A device used to return some of the turbocharger
output air back to the turbocharger to raise the
exhaust temperature when needed for active
regeneration of the diesel particulate filter.
Electronic Unit Injector (EUI)
Controlled electronically by the EECU, there is
one electronic unit injector for each cylinder of an
engine. A unit injector incorporates the pump, the
injector nozzle and the solenoids in a single body.
Actuated by the camshaft via rocker arms with
roller followers, electronic unit injectors offer very
quick response at very high pressure.
Engine Electronic Control Unit (EECU)
A microprocessor-based controller mounted on
the cylinder block. On the MP7 engine, a cooling
plate mounts on the surface of the module. A tube
on the plate conducts fuel drawn from the tank on
its way to the pump before being pressurized.
The fuel acts as the coolant. With the MACK
V-MAC IV system, the EECU controls fuel timing
and delivery, exhaust gas recirculation, fan
operation, engine protection functions and engine
brake operation.
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