Injection Control
The pressure control system uses hydraulically-actuated injectors to pressurize the fuel inside of injectors. Engine oil is used to actuate injectors. Oil is drawn from oil pan through the pick-up tube by engine oil pump. Engine oil pump is a rotor-type pump driven by crankshaft. Oil is fed through passages in front cover to an oil reservoir mounted on top on front cover. The oil reservoir makes a constant supply of oil available to the high pressure oil pump mounted on top of engine. See Fig 1. Injection Pressure Regulator (IPR) controls oil pump injection oil pressure between 450-3000 psi (3102-20,685 kPa). See INJECTION PRESSURE REGULATOR .
High pressure oil is sent to oil galleries machined in cylinder heads. An Injection Control Pressure (ICP) sensor is mounted on one of the oil galleries and sends an analog voltage signal to PCM for feedback control of oil pressure. When an injector is electrically energized, a poppet valve is opened by an electronic solenoid mounted on injector. See Fig 2. Oil pressure is then allowed to flow into injector and act on the amplifier piston. When injection is ended, pressure on top of amplifier piston is vented by the poppet valve through the top portion of injector. Oil is then directed by oil troughs mounted on injector to a push tube hole to return to crankcase.