D
Volvo Trucks North America
Date
Group
No.
Page
Service Bulletin
11.2006
230
247
4(11)
Fuel System Components
W2004976
Current Volvo engines are electronically controlled diesel
engines designed to meet today’s strict environmental
standards. Meeting these standards requires optimum
combustion. This demands, among other things, injecting
the exact amount of fuel into the combustion chamber
under very high pressure at precisely the correct time,
depending on engine speed, load, temperature and other
conditions.
Totally mechanical injection systems cannot meet these
demands and so requires that engines are equipped with
an electronically controlled injection system. An Engine
Electronic Control Unit (EECU) receives electrical signals
from the accelerator pedal and a number of other sensors
on the engine. These sensors provide speed, pressure
and temperature signals, sent to the EECU, which in turn
governs the fuel injection procedure. The EECU has a
built-in diagnostic system, which electronically detects
and traces several faults in the fuel system.
Each cylinder has four valves. Individual differences
always occur between the cylinders in an internal
combustion engine. The engine has a cylinder balancing
system, the purpose of which is to even out the amounts
of fuel between the cylinders. Cylinder balancing takes
place with the engine running at idle speed, providing
certain preconditions have been met.
