32 1 ENGINE SYSTEMS
End of Main Injection (Step 1)
Figure 26 End of m ain injection (Step 1)
1. C LOSE coil (on)
2. OPEN coil (off)
3. Needle (unseated / closing)
4. Check disk (seated)
When the Injector Drive Modu le (IDM) determines
that the correct injector on-time has been reached
(the correct amount of fuel has been delivered), the
IDM sends a pulse-width controlled current to the
CLOSE coil of the injector. The current energizes
the CLOSE coil and magnetic force closes the spool
valve. High-pressure oil is deadheaded against the
spool valve.
End o f Main In je c tio n (Step 2)
Figure 27 End of main injection (Step 2)
1. CLOSE coil (off)
2. OPEN coil (off)
3. Needle (seated)
The pulse-wid th controlled curre nt to close the coil
is shut off, but the spool valve remains closed. The
intensifier piston and plunger return to their initial
positions. Oil above the intensi fier piston flows past
the spool valve through the exhaust ports. Fuel
pressure decreases until the needle control spring
forces the needle back onto its seat.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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