Microinjection Quantity Learning Control - Denso 4D56 Service Manual

(3) Injection Timing Calculation Method
[1] Outline of Timing Control
0
NE Pulse
Solenoid Valve Control Pulse
Nozzle Needle Lift
[2] Injection Timing Calculation Method
Engine Speed
Injection Quantity

11.3 Microinjection Quantity Learning Control

(1) Outline
• Quantity learning control is used in every vehicle engine (injector) to preserve the accuracy of quantity (specifically, pilot injection
quantity.)
This type of control is first performed when shipped from the factory (L/O), and later is automatically performed every time the vehicle
runs a set distance (for details, see item "A".) Because of quantity learning control, the accuracy of each injector can be preserved not
only initially, but also as deterioration in injection occurs over time. As a result of this learning, correction values are recorded in the
ECU. During normal driving operations, this correction value is used to make modifications to injection commands, resulting in ac-
curate microinjection.
(2) Learning Operations
• For every two no load, idle instability conditions established (See chart "A" below) quantity learning takes place.
In addition, it is also possible to perform quantity learning control manually as a diagnostic tool.
1
Pilot Injection
Pilot Injection Timing
Basic Injection
Timing
Operation Section
Actual TDC
Main Injection
Main Injection Timing
Pilot Interval
Main Injection
Corrections
Timing
1 33
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QB0724E