Automobile Inspection Technology

Chapter 11 Automotive Engine Detection (7)
a. Click the "Temperature Detection" button in the "Gasoline Engine Detection" menu, the system enters the temperature detection state, and displays the temperature of the measured part and the engine speed, as shown in Figure 2-54.

b. Click the temperature detection mode on the upper left, and select the temperature to be measured in the pop-up window.

(1) Exhaust gas analysis
①Connection before testing: Connect the exhaust gas analyzer to the EA-232 engine comprehensive performance testing instrument through the RS-2000 interface of the main engine.Insert the exhaust gas detection tube into the exhaust pipe.

② Detection steps:
a. Start the engine to make it work at normal temperature.

b. Click the "Exhaust Gas Analysis" button in the "Gasoline Engine Detection" menu, and the system will enter the exhaust gas detection interface. The default interface is a line graph.

a. Click the "Detect" button, and select the display method in the pop-up window, that is, display in a histogram or a line graph.If the histogram is selected, it will be as shown in Figure 2-55.

(12) Speed ​​stability analysis

①Connection before detection: Clamp the signal adapter of the first cylinder to the high voltage line of the first cylinder.

②Testing steps: Click the button "Speed ​​Stability Analysis" under the "Gasoline Engine Test" menu, and the system will enter the speed test
Figure 2-54 Temperature detection

The rubber hose on the pressure adapter (1280407) is connected to the joint of the engine vacuum pipe through a tee, and the one-cylinder signal adapter is clamped on the one-cylinder high-voltage line, as shown in Figure 2-53.

The vacuum hose of the electronically controlled fuel injection engine is generally on the top of the engine assembly. After unplugging one end, it can be connected to the detector sensor through a three-way joint.

② Detection steps:
a. Make the engine speed stable at about 1700r/min.

b. In the submenu under the main menu, select "vacuum degree in the intake pipe" to enter the vacuum degree detection status interface.

a. Press the "Detect" button at the bottom of the detection interface, the detector collects the vacuum value of the intake manifold at high speed, automatically detects and displays the vacuum waveform in the intake manifold and the current engine speed.

The measurement status, and display the real-time speed of the engine and the highest and lowest speed in 32 cycles; the user can also input the average cycle value by himself.As shown in Figure 2-56.

(13) No-load dynamometer

①Connection before detection: Clamp the signal adapter of the first cylinder to the high voltage line of the first cylinder.

② Detection steps:
a. Click the "No-load Dynamometer" button under the "Gasoline Engine Detection" menu, and the system will enter the no-load dynamometer interface or click the "Mode Selection" button to select P to enter the no-load dynamometer interface.

b. Set the idle speed (engine idle speed), rated speed (engine rated speed) and equivalent moment of inertia (equivalent moment of inertia can be obtained by testing on the same type of car - but the car must be in good working condition ).

c. Click the "Detect" button, the system starts to count down.

d. When the count is zero, step on the accelerator pedal of the car quickly to increase the engine speed as quickly as possible. When the engine speed exceeds the set rated speed > 2, quickly release the accelerator pedal to return the engine to idle speed. The system will automatically detect the output power of the engine and display it, as shown in Figure 2-57.

②Choose the "Method Selection" button, and select the detection moment of inertia detection button in the pop-up window to enter the moment of inertia detection.

③ Set the idle speed center, the rated speed shape and the rated power of the vehicle to be tested.

④Click "Detect" and the system will start counting down (after "Detect" is clicked, it will change to "Stop" and after it is pressed again, "Stop" will return to "Detect" and the system will stop detecting).

⑤ When the count is zero, step on the accelerator pedal of the car quickly to increase the engine speed as quickly as possible. When the engine speed exceeds the set rated speed, release the accelerator pedal quickly to make the engine
The engine returns to the idling condition; the system will automatically detect the moment of inertia of the engine and display it.

(Section [-]) Engine performance testing training

【Training project [-]】Cylinder compression pressure detection

1. Training content
①Measure the cylinder compression pressure with a cylinder pressure gauge according to the correct operating procedures.

②Judge whether the cylinder pressure meets the technical standards.

③ The cause of the fault can be analyzed according to the compression pressure of the cylinder.

④ After troubleshooting, the engine can work normally.

2. Purpose of training
① Understand the empirical method, intuitive method, and the method of measuring the starter current or voltage to check the cylinder pressure.

② Familiar with measuring cylinder pressure with cylinder pressure gauge.

③Master the cause of failure through cylinder pressure analysis.

④ Eliminate engine failures caused by cylinder pressure.

3. Equipment, tools and materials
① 1 engine assembly in good technical condition, and set faults according to requirements.

② When troubleshooting, some parts with qualified performance can be replaced.

③ One spark plug sleeve, one cylinder pressure gauge and one tester for measuring the current or voltage of the starter.

4. Operation steps
① Remove all spark plugs or fuel injectors and air filters.

② Check the cylinder pressure gauge.

③Measure the cylinder pressure cylinder by cylinder.

Preconditions: It must be ensured that there is sufficient starting speed and sufficient battery pressure; fully open the throttle valve and choke valve;

The motor should reach the normal operating temperature, the coolant temperature should reach 85-95°C, and the engine oil temperature should reach 70-90°C; for the electronic ignition engine, the central high-voltage wire plugged into the distributor cover should be unplugged and its Ground the iron to prevent the electronic components from being damaged by high-voltage electric shock; for those equipped with a fuel cut-off solenoid valve, the connector of the fuel cut-off solenoid valve should be disassembled.

Measure the cylinder pressure: Use a cylinder pressure gauge to measure cylinder by cylinder, measure 3 times for each cylinder, and take the maximum value.

Analysis: Under normal circumstances, the cylinder pressure of each cylinder should not be lower than 8% of the specified value, and the pressure difference of each cylinder should not be greater than 3%.The cylinder pressure of a general car is 1.0-1.3MPa.

④Faults caused by low cylinder compression pressure can also be roughly diagnosed by the following two methods:

a. Check the cylinder pressure visually.Press the plug hole of the train with your finger, start the engine, and feel the cylinder pressure with your finger pressure.During the inspection, it can be compared with other cylinders, and the cylinder with little reaction force of compressed gas in the cylinder is the cylinder with insufficient cylinder pressure.

b. Check the cylinder pressure empirically.If there is a tendency to reverse when starting the engine, it may be that the ignition is too early; if the engine starts with the starter turning, and turns off when the starter stops, it is generally a fault in the primary circuit of the ignition system. If the fire is fired again, it may be that the ignition is wrong or the gas distribution is wrong; if the exhaust pipe emits black smoke when starting, it may be that the mixture is too rich.If the carburetor is accompanied by rhythmic continuous tempering when starting, it may be that the intake valve is not closed tightly or the exhaust valve opening is too small.

[Training project [-]] Engine oil quality inspection

1. Training content
① Determination of engine oil filter paper spots according to the correct operating procedures.

② According to the correct operating procedures, carry out the measurement of the color gamut signs of oil drop spots.

③Judge whether the engine oil meets the technical standards.

④Able to analyze the cause according to the engine oil test results.

2. Purpose of training
①Master the methods for the detection of engine oil filter paper spots and the color gamut signs of oil drop spots.

②Familiar with the use of related instruments for oil quality testing.

③ Grasp the cause of failure through engine oil quality analysis.

3. Determination of spots on engine oil filter paper
Note: The detection of engine oil filter paper spots is carried out according to the provisions of GB/T8030-1987 "Lubricating Oil Field Inspection Method".

(1) Test instruments and materials

①Frame: It is a two-hole or nine-hole spot test frame made of two pieces of plexiglass or cardboard, with a hole diameter of 50mm.

②Drop rod: stainless steel rod or glass rod, 2mm in diameter, 140-200mm long, with a tapered tip, and a scribed line 40mm away from the tip to control the sampling volume.

③Filter paper: Comply with the provisions of GB1915 "Qualitative Filter Paper", with a diameter of 9cm or special filter paper.

Steps
① Clamp the filter paper in the frame and place it on a flat surface so that the back of the filter paper does not touch the object, so as not to affect the diffusion of oil droplets.

②Put the sample in a sample bottle of no more than 3/4 volume, and shake it fully to mix the impurities deposited at the bottom of the bottle.Immediately insert the sample with a clean drip stick until the liquid level reaches the line on the drip stick, then lift it up vertically.Drip the oil intermittently on the drip stick, take the 5th-6th drop, the top of the drip stick is about 30mm away from the filter paper surface, and carefully drop it vertically on the center of the filter paper circle.

③Leave it at room temperature for 0.5-1h, and observe the speckle image.

4. Determination of color gamut signs of oil drop spots
Note: The color gamut signs of oil drop spots are determined according to the provisions of NY/T512-2002 "Rapid Test Method for Lubricating Oil Quality".This method is not only applicable to engine oil, but also to vehicle gear oil, etc.

(1) Test instruments and materials

① Quantitative filter paper: in line with the requirements of GB/T1914-1993 "Chemical Analysis Filter Paper", with a diameter of 7cm.

②Oil analysis agent: specially made.

(2) Measurement method
① Clamp the quantitative filter paper in the frame and place it on a flat surface so that the back of the filter paper does not touch the object, so as not to affect the diffusion of oil droplets.

②Put the sample in a sample bottle of no more than 3/4 volume, and shake it fully to mix the impurities deposited at the bottom of the bottle.

③Put a drop of oil analysis agent into the center of the quantitative filter paper, insert a drop of the test sample with a clean drop stick immediately after the diffusion, lift it up vertically until the liquid surface reaches the line of the drop stick, and drop it into the center of the quantitative filter paper dripped with the analytical agent One drop test oil.

④Let the quantitative filter paper stand at room temperature for 0.5-1h. After it is naturally air-dried, compare it with the oil drop spot color gamut sign control map to judge the quality of the lubricating oil.

【Training project [-]】Comprehensive engine performance testing

1. Training content
① Carry out the comprehensive performance test of the gasoline engine according to the correct operating procedures.

②Comprehensive performance testing of the diesel engine is carried out according to the correct operating procedures.

③Judge whether the overall performance of the engine meets the technical requirements.

④ The reason can be analyzed according to the test results of the comprehensive performance of the engine.

2. Purpose of training
①Master the detection method of comprehensive performance of gasoline and diesel engines.

②Familiar with the use of engine comprehensive performance tester.

③ Master and analyze the causes of failures through the detection and analysis of the comprehensive performance of the engine.

3. Gasoline engine comprehensive performance testing method

Refer to (Section VII), use the EA-2000 automobile engine comprehensive performance tester to test the comprehensive performance of the gasoline engine.

4. Diesel engine comprehensive performance testing method

Taking the Yuanzheng EA-1000 engine comprehensive performance analyzer as an example, the usage of the analyzer is introduced.

(1) Preparation Work Analyzer preparation.

① Turn on the power supply (220V±10%, 50Hz), turn on the main switch of the analyzer, the main switch of the microcomputer and the switch of the microcomputer display, and warm up the machine for 20 minutes.

② When the engine is not working and the ignition system is off, connect the signal extraction system to the engine under test.

③The power cord must be reliably grounded.

④ When testing the electronic controller (ECU) of the electronically controlled fuel injection engine, in addition to the grounding of the instrument power supply, the instrument ground wire must be shared with the engine, and the tester must be in contact with the car body at any time.

start analyzer

Click the "Modify" button to record the car user
① The analyzer has been preheated.

② Double-click the “Launch Engine Analysis” icon on the display with the left mouse button to start the comprehensive performance testing program of the analyzer.

③Analyzer host performs self-inspection on single-chip communication and 8 adapters one by one.If the self-test is passed, it will be green, and if it fails, a prompt will be given.

④The interface of “Record user information” appears on the display screen.Click the "Modify" button to record the car user information, and then click the "OK" button, the main and sub-menus of detection will appear on the display.The main and sub menus and partitions of the display screen are shown in Figure 2-59.

⑤ On the main menu, select the items to be tested such as "gasoline engine", "diesel engine", "electronically controlled engine parameters" or "fault analysis".If the car user data has not been entered in the previous steps, just select the "Parameter Setting" data and click "OK".

⑥ To clear the data of the previous test, press the "F2" key or click the "Clear Data" button at the bottom of the display.

(3) Detection method

The specific detection method of the analyzer is introduced below by taking diesel engine detection as an example.

Click "Diesel Engine" to list 6 inspection items in the sub-menu: fuel injection pressure, fuel injection advance angle, generator and starter speed stability analysis, emission detection and no-load dynamometer, and any item can be selected by clicking to test.

①Injection pressure detection:
a. Before the test, install the red 6mm fuel injection pressure sensor on the high-pressure fuel pipe under test, and the other black clip should be well grounded.As shown in Figure 2-60.

b. Click the "Injection Pressure" with the left mouse button to enter the injection pressure detection interface.

c. After selecting the cylinder number, click the "OK" and "Detect" buttons, and the waveform of the fuel injection pressure of the cylinder under test will appear. If necessary, click the "Save Waveform", "Save Data", and "Graphic Print" buttons to edit the waveform and data. Store and print, as shown in Figure 2-61.

d. When measuring the fuel injection pressure of other cylinders, the red 6mm fuel injection pressure sensor should be installed on the high-pressure fuel pipe of other cylinders under inspection, and the method is the same as above.

e. Click "Show Menu" to return to the main and sub-menus.

② Fuel injection advance angle detection:
a. Before testing, the red 6mm fuel injection pressure sensor must be installed on the high-pressure oil pipe of the first cylinder or the last cylinder, and the black clip should be well grounded.

b. Click "Injection Advance Angle" with the left mouse button to enter the fuel injection advance angle detection interface, as shown in Figure 2-62.

Plug the 1280407 timing signal line to the timing light, return the timing light potentiometer to "0", press the timing light switch, and the timing light will flash.

d. Align the timing light with the top dead center mark on the flywheel or crankshaft drive pulley, adjust the potentiometer on the timing light, gradually.

e. Read the fuel injection advance angle value and the engine speed value.

f. Click the "Save Data" button to save the ignition advance angle and speed values.

g. Click "Show Menu" to return to the main and sub-menus.

③ Generator and starter detection:
Refer to gasoline engine comprehensive performance testing: starting and charging current and voltage detection.

④Speed ​​stability detection:
a. Select "Speed ​​Stability Analysis" in the sub-menu of "Diesel Engine" to enter the engine speed analysis interface, as shown in Figure 2-63.

b. The engine is running at idle speed. At this time, the speed is the most unstable. Read the maximum speed and the minimum speed under a certain number of cycles. The smaller the speed difference, the better.
.
The number of cycles can be set by yourself.

d. Click "Save Data" to save the data.

e. Click "Show Menu" to return to the main and sub-menus.

b. Set the starting speed Tm and the ending speed Tr.

C. Equivalent moment of inertia of key person.

d. Click the "Detect" button, and a 5S countdown will appear on the interface.

e. Depress the accelerator pedal quickly when the countdown is over, and lift the accelerator pedal when the engine speed exceeds.Read the acceleration time and maximum average acceleration power of the engine.

g. Click the "Save Data" and "Print Report" buttons to save and print the data.

h. Click "Show Menu" to return to the main and sub-menus.

thinking and practice
1. What are the main parameters for evaluating engine technical performance?

2. What is the steady-state dynamometer and dynamic dynamometer of the engine?
3. How to test the cylinder compression pressure and analyze it.

4. How to detect the vacuum degree of the intake pipe?
5. What can be understood by observing the ignition waveform of the gasoline engine?

6. How to diagnose engine failure according to ignition waveform?
7. How to detect the ignition advance angle of gasoline engine?
8. How to detect the fuel injection advance angle of diesel engine?
9. Briefly describe the detection method of the technical condition of the fuel injector.

10. How to conduct oil pressure test and oil quality test?
11. What are the functions of engine comprehensive performance testing?How to use it correctly?

(End of this chapter)