View Single Post
Old 04-05-2012, 05:27 PM   #9
06VT365
Senior Member
 
06VT365's Avatar
 
Join Date: Mar 2012
Location: Des Moines, IA
Posts: 364
Rep Power: 13
06VT365 is on a distinguished road
Default

http://www.blackclouddiesel.com/Tech/howinjectrswrk.htm

Copied from the link above....explains how the HEUI Injectors work.

Understanding how the injectors work on the PowerStroke engine can help in diagnosing a concern with this engine. Older diesels used a hydraulic injection system in which fuel pressurized by the injection pump would actuate the injector. The drawback to this system is that any air which enters the fuel lines will affect the operation of the injectors, or even prevent them from operating. Also, the amount of fuel injected is dependent on the mechanical operation of the injection pump governor, which adjusts volume based on engine load/RPM.
Gasoline engines with electronic injection use a pressurized fuel system and the computer varies the actuation of the injector based on input from various sensors in order to control the amount of fuel to the cylinders. Since gasoline engines have an ignition system to ignite the air/fuel mixture in the cylinders, fuel pressure only needs to be sufficient to supply the injectors and provide an adequate spray pattern to ensure efficient combustion. But a diesel engine uses heat from compression to ignite the air fuel mixture, and this high compression requires high injection pressures.
What has been done on the PowerStroke is both of these systems are used in conjuntion with each other. Fuel is supplied to the injectors through fuel rails inside the cylinder heads. Also supplied to the injectors is high pressure engine oil. As the computer determines that a cylinder should fire it signals the Injector Driver Module. The IDM sends a 110 volt pulse-width modulated signal to the injector solenoid. When the injector solenoid is actuated, it opens a poppet valve which allows high pressure oil to flow into the intensifier piston. The intensifier piston is forced down, pressurizing the fuel inside the injector. When fuel pressure inside the injector reaches approximatly 2700 psi, it causes the injector pintle to rise off its seat and fuel is injected into the cylinder from the nozzel. As long as the poppet valve is open and oil is flowing into the injector, fuel will be injected.

The computer controls how long the injector solenoid is energized (pulse-width, or time on in milliseconds), but it also determines the pressure of the fuel being injected by controlling the pressure of the oil (IPR duty-cycle, or the percentage of time on vs. off--AKA dwell) in the cylinder heads. The computer determines this based on engine load and driver demand by monitoring various sensors. Since the cavity at the top of the intensifier piston is seven times the size of the fuel cavity at the bottom, fuel is injected at a pressure seven times that of the computer-controlled oil pressure--oil pressure 3000 psi = injected fuel pressure 21000 psi. Due to the high oil system pressures, the spring which closes the poppet valve once the injector solenoid is deactivated has to be very strong--and because of this, the solenoid needs to be 110 volts. Once the poppet valve is closed, spring pressure returns the injector to its normal state and the oil is exhausted into the valve cover area to return to the sump.


Hope that helps explain my last post.
__________________
2006 Chevy Express Cargo Van
6.6 Duramax
Stock - For Now


Sold
2006 F350 CC LB 4x4
MBRP - SCT X3 Vivian Tuned - Glowshift - Insight CTS - Sinister Coolant Filter -20 x 10 Moto Metal 957's - 295/60/20 Nitto Trail's - Vortex Liner - B&W



2002 F250 CC SB 4x4
International T444E Power
Bullydog 6 position chip
06VT365 is offline   Reply With Quote