International Trucks Engine Service Manual. Service diagnosis is an investigative procedure that must be followed to find and correct an engine application problem or an engine problem. If the problem is engine application, see specific vehicle manuals for further diagnostic information.
The VGT responds directly to engine loads. During heavy load, an increased flow of exhaust gases turns the turbine wheel faster. This increased speed turns the compressor impeller faster and supplies more air or greater boost to the intake manifold. Conversely, when engine load is light, the flow of exhaust gases decreases and less air is pumped into the intake manifold.
Air enters and flows through the air filter assembly and mixes with air from crankcase ventilation. The VGT compresses the air mixture before it enters the Charge Air Cooler (CAC). Cooled compressed air flows from the CAC into the air intake manifold that directs air to the intake ports for each cylinder head.
The CAC cooler is mounted on top of the radiator. Air from the VGT is pushed through a network of heat exchanger tubes before entering the air intake manifold. Outside air flowing over the tubes and fins cools the charged air. Charged air is cooler and denser than the uncooled air; cooler and denser air improves the fuel-to-air ratio during combustion, resulting in improved emission control and power output.
Fuel injector features
Two 48 volt 20 amp coils control a spool valve that directs oil flow in and out of the injector. The injector coils are turned on for approximately 800 (micro second or millionth of a second). Each injector has a single four pin connector that passes through the rocker arm carrier
Intensifier piston
When the spool valve is open, high pressure oil enters the injector, pushing down the intensifier piston and plunger. Since the intensifier piston is 7.1 times greater in surface area than the plunger, the injection pressure is also 7.1 times greater than ICP pressure on the plunger.
Plunger and barrel
Fuel pressure builds between the plunger and the barrel. When the intensifier piston pushes the plunger down, the plunger increases fuel pressure in the barrel 7.1 times greater than ICP. The plunger has tungsten carbide coating to reduce scuffing and poor performance.
Injector needle
The injector needle opens inward, off its seat when fuel pressure overcomes the Valve Opening Pressure (VOP) - approximately 21 MPa (3100 psi). Fuel is atomized at high pressure through the nozzle tip.