Checking the injectors (Hyundai Sonata EF)

General information

The injectors inject fuel into the engine cylinders based on a signal from the electronic engine control unit. The amount of fuel supplied by the injector is determined by the time during which the control pulse is applied to the injector winding (the open state time of the injector needle valve).

During normal engine operation, asynchronous (sequential) fuel injection by injectors is almost always used. Synchronous (simultaneous) fuel injection by injectors can be used when starting the engine, when the crankshaft is turned by the starter.

Engines 2.0 l / 2.4 l.

Engine 2.7 l.

Troubleshooting Guide

1. If you have difficulty starting a warm engine, check for low pressure in the fuel lines and the tightness of the injectors.

2. If the engine does not start and the injectors do not work when the crankshaft is turned by the starter, then check for the following faults (not related to the injectors):

• a) Malfunction of the power supply circuit of the electronic engine control unit or the ground connection circuit.
• b) Malfunction of the engine control relay and fuel pump relay.
• c) Malfunction of the crankshaft position sensor and camshaft position sensor.

3. If after disabling the injector of one of the cylinders there is no change in the engine operation in idle mode, then perform the following checks for this cylinder:

• a) Check the injector and its wiring harness.
• b) Check the spark plug and spark plug wire.
• c) Check the compression.

4. If the injector operating time (injector opening signal duration) differs from the nominal value, even if the test showed that the injector and its wiring harness are in good condition, then check for incomplete combustion in one of the cylinders (due to a faulty spark plug, ignition coil, lack of compression, etc.)

Checking the operation of the injectors

1. Using a phonendoscope, check the operation of the injector (the presence of characteristic creaking sounds) when the engine is idling. Make sure that as the engine crankshaft speed increases, the frequency of the injector operation also increases.

Note: Do not confuse the sound of the injector being tested with the sound of the adjacent injector being tested, transmitted through the fuel rail, especially if the injector being tested is not working.

Engines 2.0 l / 2.4 l.

Engine 2.7 l.

2. If you don't have a phonendoscope, check the injector operation by touching it with your finger. If you don't feel vibration from the injector, check the wiring harness connector, the injector, or the presence of a control pulse from the engine control unit.

Engines 2.0 l / 2.4 l.

Engine 2.7 l.

Checking with a tester

1. Read the tester readings (injector opening time) when the crankshaft is turned by the starter.

Table. Nominal values.

Coolant temperature	Nominal value
0°C	Approximately 17 ms
20°C	Approximately 35 ms
80°C	Approximately 8.5 ms

2. Perform further testing under the following conditions.

• a) Coolant temperature: 80-95°C;
• b) Lighting, electric fan and all additional equipment: Off;
• c) Gearbox: Neutral gear (position "P" of the automatic transmission selector);
• d) Steering wheel: In the straight-ahead position.

3. Performing the check:

Read the tester readings (injector opening time).

Table. Nominal values.

Engine condition	Nominal value
Idling	2.2-2.9 ms
2000 rpm	1.8-2.6 ms
When you press the accelerator pedal sharply	It is increasing

Note:

• The injector opening time is shown when the supply voltage is not less than 11 V and the rotation speed is 250 rpm or less when the engine crankshaft is cranked by the starter.
• When the engine coolant temperature is 0°C, the electronic engine control unit ensures simultaneous fuel injection into all four cylinders.
• On a new car (mileage less than 500 km), the injector opening time may be approximately 10% longer than specified.

(The original text is published on the website hyundaibook)

Checking actuators:

1. Start the engine and read the tester readings when the engine is warmed up and idling (after the engine has warmed up, check the idle speed by turning off the injectors in the specified sequence).

Table. Nominal values.

Tester readings - item no	Normal condition
01. Nozzle No.1	Activated
02. Nozzle No.2	Activated
03. Nozzle No.3	Activated
04. Nozzle No.4	Activated
*05. Nozzle No.5	Activated
*06. Nozzle No.6	Activated

Note: "*" - for 2.7 l engine.

2. When the injector is disconnected, the engine operation at idle speed becomes unstable.

Checking the resistance of the injector winding

1. Measure the resistance of the injector winding between the connector terminals using an ohmmeter.

• Nominal value: 13-16 Ohm at 20°C

2. If the resistance does not correspond to the nominal value range, replace the injector.