The following SINOCMP introduces the maintenance method of the injector and the failure case analysis of the injector of the 5 kinds of cars.
(1) Structure of the injector
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| Figure: injector structure |
There are two O-ring on the injector, and the lower seal ring is located between the injector and the air inlet. Each time the injector is removed, the lubrication seal circle must be replaced. The O-shaped sealing circle has a thermal insulation effect, which can prevent fuel from forming air resistance in the injector, thereby improving the hot start performance, and also preventing the injector from being excessively perturbed. The upper seal chart is used to ensure the seal between the injector and the fuel manifold. Fuel pressure is 250 ~ 350kpa, the impedance of the electromagnetic coil is 12.2Ω, high impedance.
(2)Disassembly of the injector
Dismantle the fuel injector to prevent damage to the conductive needle post and fuel injection hole in the connector. The injector assembly cannot be cleaned in any cleaning agent.
When disassembling, the fuel main should be fixed to prevent damage to other components. Replacement of the injector must use the same model and the same flow of injector. The removal steps are as follows:
[1] Release fuel system pressure.
[2] Remove the intake manifold.
[3] Remove the electrical connector and fuel main.
[4] Remove the retaining clip and remove the fuel injection pipe from the fuel main pipe.
[5] During installation, proceed in the reverse order of removal. The O-ring must be replaced with a new one.
Inspection method of fuel injector
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| Figure: Detecting the solenoid coil resistance of the injector |
[1] When the engine is running, place your finger on the injector and feel the vibration as normal.
[2] Unplug the control plug of a certain cylinder injector during engine operation. If the engine speed drops or is unstable, it means that the cylinder injection is working normally.
[3] Detect the solenoid coil resistance of the injector as shown in Figure 1-80. Low-resistance fuel injection, high precision digital multimeter detection. Cold start oil injector resistance value is 2-5Ω is normal, low resistance value injector is normal at 1.5-3Ω, the high resistance value of the main injector is about 13Ω. The coil must not be short-circuited, open-circuited, or grounded, otherwise, it should be replaced.
(2) Fuel injection test
[1] Spray test. Remove the fuel injector, connect the fuel supply pipe and the battery or connect the 3V power supply, and touch the positive electrode of the battery with a wire.
[2] Oil drop test. Do not power up the injector, but the electric fuel pump continues to pump oil. It is normal for the fuel injection nozzle to drop more than 1 drop per minute.
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| Figure: Injector fuel injection test |
[4] Simple inspection method. Two dry batteries (approximately 3V) can be connected to the injector to blow air to the injector. When it is not energized, it cannot be blown, and air leakage is normal; when it is energized, it is normal to blow.
Injector maintenance example 1
Model: Fukang AL car.
(1) Failure phenomenon, rapid instability, engine speed fluctuates between 700-800rmin, the engine is susceptible to fire when cold, and the engine power is insufficient during driving.
(2) Causes of the fault The fuel injector is glued due to dirty fuel, the fuel injection quantity is insufficient, the air-fuel ratio is incorrect, causing rapid instability and insufficient engine power.
(3) Diagnosis and exclusion methods
[1] The computer detects the mixing ratio concentration and automatically adapts to temporary failures.
[2] Clean the valve body, inlet pressure sensor and pipeline of the total speed rotary valve.
[3] Check the ignition timing.
[4] Replacing 93 # gasoline, the effect is not obvious.
[5] Check the fuel system pressure at 250kPa, which is normal.
[6] Check that the fuel injection is dirty, and the vehicle returns to normal after cleaning.
Injector maintenance example 2
Model: Fukang 988.
(1) Failure phenomenon The vehicle runs normally. When the vehicle is parked for more than 10mm, it is difficult to start the engine. Enlarging the throttle opening can start the engine.
(2) The cause of the fault is the poor seal of the injector, the gasoline leaked from the injector into the interior of the gas red, and the starting gas is too rich to cause difficulty in starting.
(3) Diagnosis and exclusion methods
[1] Check that the fuel pressure is normal.
[2] Check that the high-voltage power of the ignition system works normally.
[3] Clean quick reading and intake pressure sensor.
[4] The smell of gasoline was found when the spark base was disassembled.
[5] After removing the injector and cleaning it, the injector has leaked oil. After replacing the injector, the engine starts normally.
Injector maintenance example 3
Model: Jetta GT.
(1) Failure phenomenon The engine has insufficient power, poor acceleration, and unstable speed.
(2) Fault diagnosis
[1] Query no fault code storage with VAG1552 fault diagnosis instrument.
[2] Check that the warehouse speed HC exceeds the standard.
[3] Check that the spark plug is working properly.
[4] Removed the injector and found that there were two red fuel injection plugs.
(3) Elimination method After the fuel injector is cleaned and tested, the engine works normally.
Injector maintenance example 4
Model: Suda GT
(1) Failure phenomenon The color speed of the engine is trembling.
(2) Fault diagnosis
[1] Query no fault code storage with VAG1552 fault diagnosis instrument
[2] Inspection found that there was a bad seal of the red injector.
(3) Elimination method After the fuel injection seal ring was replaced, the engine was running normally.
Injector maintenance example 5
Model: GTX type of car.
(1) Failure phenomenon The engine accelerates badly.
(2) Fault diagnosis
[1] Use the VAG1552 fault diagnosis instrument to query the storage of unreasonable code.
[2] Check that the idle exhaust gas is normal.
[3] Check that the wire from the injector to the ECU is frayed, and the fuel injection of the injector is out of control.
(3) Elimination method After the broken wire is repaired and tested, the engine accelerates well.
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