IDLE SPEED CONTROL [SKYACTIV-D 1.5]

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Outline

• The PCM controls the fuel injection amount so that the target idle speed according to the engine operation conditions is obtained.

Block Diagram

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Operation

• The fuel injection amount is controlled so that the actual idle speed is close to the target idle speed.

• The target idle speed is set under various conditions and consists mainly of the following control items.

Item

Control description

Target idle speed

Engine speed control during normal operation

The actual idle speed conforms to the target idle speed during normal idling.

ATX: 775 rpm

MTX: 800 rpm

Engine speed control during warm-up

Approaches the target engine speed during warm-up based on the input signal from ECT sensor and IAT sensor.

775—1,500 rpm

Engine speed control during fuel injection amount learning

During fuel injection amount learning, the engine speed is controlled so that it matches the target engine speed.

During auto-learning control

800 rpm

During manual learning control

800—1,500 rpm

DPF regeneration control

Controls the engine speed during DPF regeneration control so that it matches the target engine speed.

Auto DPF regeneration control

800—925 rpm

Compulsory DPF regeneration control

1,750 rpm^*

Item	Control description	Target idle speed
Engine speed control during normal operation	The actual idle speed conforms to the target idle speed during normal idling.	ATX: 775 rpm MTX: 800 rpm
Engine speed control during warm-up	Approaches the target engine speed during warm-up based on the input signal from ECT sensor and IAT sensor.	775—1,500 rpm
Engine speed control during fuel injection amount learning	During fuel injection amount learning, the engine speed is controlled so that it matches the target engine speed.	During auto-learning control 800 rpm During manual learning control 800—1,500 rpm
DPF regeneration control	Controls the engine speed during DPF regeneration control so that it matches the target engine speed.	Auto DPF regeneration control 800—925 rpm Compulsory DPF regeneration control 1,750 rpm^*

* :If there is incorrect combustion of soot during diesel particulate filter regeneration, the exhaust gas temperature increases which may cause damage to the diesel particulate filter. In this case, post injection is stopped and the engine speed increases to 2,500 rpm. Due to this, low temperature exhaust gas is sent to the oxidation catalytic converter at high speed and the diesel particulate filter is cooled to prevent damage.

• The A/C operation information from the A/C pressure sensor is input to prevent the idle speed from decreasing by A/C load. The fuel injection amount is corrected to maintain idle speed when the A/C load is applied.

In addition, the fuel injection amount is corrected to prevent a decrease in speed when the electrical load is applied.