Injector Failure Phenomenon and Good or Bad Detection Method

From: http://www.sinocmpinjector.com

In the process of using the injector, we will encounter many problems. Let us learn and understand the Injector failure phenomenon and good or bad detection method.

Injector Failure Phenomenon:

If the engine fuel system lacks maintenance (regularly clean the injectors), it may cause glue accumulation inside the injector and the valve hole will be blocked or the needle valve stuck.
Blocked injector valve holes will result in the inability to inject fuel (full blockage) or poor injection atomization (partial blockage), and stuck needle valves will cause dripping after injection, resulting in engine idling instability, poor acceleration or difficulty in starting. This phenomenon will also seriously affect the emission performance of the engine.
In addition, the water inlet of the injector connector will cause a short circuit, which will make it impossible to inject fuel. Care must be taken when cleaning. The engine fails to start, the engine runs erratically, and the exhaust gas emits severe black smoke. These are all symptoms of a broken injector.

The main fault types of injectors:

1. The valve hole is blocked and fuel injection or atomization is bad.
2. The needle valve malfunction causes flow error or leakage after injection.
3. Unable to inject fuel due to the open/short circuit of the connector.

Injector performance check method:

 1. Listen to working sound detection:

When the engine is running or starting, check the working sound of the injector with a noise stethoscope or similar tool. The operating sound cycle of the injector changes with engine speed. in case no sound or abnormal sound is heard, check the injector circuit (wiring or connector) or injector.



 

2. Resistance check:

Turn off the ignition switch and disconnect the injector connector. Use a multimeter to measure the resistance between the two terminals of the injector. It should be 12Ω at 20 ° C (68 ° F).





                                                                  3. Flow and leak inspection:

(1) Assemble the injector and transfer tool.
(2) Install a suitable vinyl tube to the injector to prevent fuel from splattering during the injection.
(3) Put the measuring cylinder under the injector.
(4) Run the fuel pump and deliver fuel to the injector.
a. Connect the tester to the DLC and execute the "component test" mode to drive the electric fuel pump to work.
b. Disconnect the fuel pump relay connector, and short the two terminals of the fuel pump relay with the maintenance wire to force drive the electric fuel pump.
(5) Use the accumulator to apply voltage to the injector for 15 seconds, measure the amount of fuel sprayed with a graduated cylinder, and measure 2-3 times per injector. The reference value for fuel injection is approximately 46cc / 15sec. If the measured value clearly exceeds the technical specifications, replace the injector.
(6) Check the leakage of the injector nozzle. Do not run the nozzle during this check (but the fuel pump should work). If the fuel leakage exceeds 1 drop/minute, replace it.

Introduction to the inspection method of the fuel injector

1. When the starter drives the engine to rotate, use a long-handled screwdriver or stethoscope to listen to whether the fuel injector has a "click, click" working sound. , At the same time of auscultation, the method of unplugging and reconnecting the injector harness plug can be used to identify whether the injector is working.
2. If the fuel injector does not work, connect the test lamp to the fuel injector's harness plug before starting the engine. If the test light flashes, the injector control system is working normally and the fault is in the injector. To check the injector, use a multimeter to measure the resistance of the solenoid coil. If the resistance value is normal, it means that the injector is blocked, the needle valve is stuck, etc., the injector should be repaired, cleaned or replaced; if the resistance value is abnormal, the injector must be replaced.
3. If the test light is off, the control system or circuit of the injector is faulty. In this regard, you should first check whether the relevant circuit of the injector is intact, and make sure that the computer is faulty under the condition that the external circuit is good.

Injector maintenance precautions:

1. Using a special cleaning analyzer to thoroughly clean the injectors on a regular basis can greatly improve the life of the injectors, and the power, fuel consumption, and emission performance can be maintained in good condition.
2. The top of the injector uses a rubber seal to connect with the fuel rail to form a reliable pressure fuel seal. The bottom also uses a rubber seal and the engine intake manifold to seal the air. Both of these parts must be replaced when the injector is disassembled.
3. When installing the injector or fuel supply pipe, first lubricate the O-ring with gasoline.
If you want to know more about the injector's failure phenomenon and more ways to check the quality of the injector, please contact us！

Maintenance Method and Failure Case Analysis of Fuel Injector

From: http://www.sinocmpinjector.com

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

 Figure: injector structure

The injector is installed on the intake pipe of each cylinder, 70-100mm away from the centerline of the intake valve, and the spray shape is a circular dimension of 25. The structure of the injector is shown in the figure.
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

  Figure: Detecting the solenoid coil resistance of the injector

(1) Check the fuel injector on the car Proceed as follows:

[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.

Figure: Injector fuel injection test

[3] The fuel injection test of the fuel injector is shown in the figure. Connect the fuel injector to the rich battery for 15s to see the fuel injection quantity. Each model has specific requirements, and relevant information should be consulted. Check the fuel injection volume difference of all injectors. Generally, it cannot be greater than 5mL in 15s.
[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.