During NORMAL injection timing, STC:
• Controls cylinder pressures
• Reduces nitrogen oxide emissions
The STC system consists primarily of:
• STC injectors
• STC oil control valve
• STC plumbing and check valve
These components control injection timing based on fuel
pump rail pressure (engine load).
In the injector, injection timing is controlled by the STC
hydraulic tappet. The tappet has an inner piston (plunger)
and an outer piston (sleeve). These tappet components
work together with the injector plunger to control injection
timing.
In NORMAL timing, no oil is in the tappet. As the
camfollower starts up the cam injection ramp, the injector
rocker lever begins to force the inner piston downward.
Because no oil is in the tappet, the inner piston must
make direct contact with the outer piston before the in-
jector plunger can begin its downward travel.
Normal Timing
• Controls Cylinder Pressures
• Reduces Nitrogen Oxide
Emissions
Fuel System General Information Section 5 - Fuel System
N14Page 5-8
To Next Page
Loading...
