EFI Engine Use and Maintenance Knowledge Points

EFI Engine Use and Maintenance Knowledge Points

Using EFI mechanism

1. When starting engine, it is generally not necessary to press accelerator pedal, because electronically controlled gasoline engine has functions such as cold start enrichment, cold car auto high idle, etc., which can ensure that engine is in a cold or hot. Started up smoothly. Conversely, if accelerator opening is too large at startup, control system will enter oil cut control state and engine will be difficult to start.

2. Before starting engine and during starting process, it is inefficient to increase amount of fuel injected by depressing accelerator pedal repeatedly and quickly. Since electronically controlled gasoline engine accelerator pedal only controls throttle opening, fuel injection amount is completely determined by computer according to parameters such as intake air volume, so operation method of carbureted engine cannot be determined. copied.

3. If a hot car cannot be started, consider an oil spill failure. At this time, you can fully depress accelerator pedal, then turn engine over, use fuel cut control to drain fuel into cylinder, and then try to start engine.

4. Do not force test machine in state of no oil. When fuel level warning light on instrument panel is on, add as much fuel as possible, because electric fuel pump is cooled by fuel flowing through it, and running without fuel will cause electric fuel pump to burn out due to overheating.

5. Do not disconnect any sensor connectors while engine is running. This will cause artificial fault codes to appear in ECU, which will affect correct judgment and troubleshooting by service personnel.

6. When yellow malfunction light on dashboard is on, it means that engine management system is malfunctioning and car should be sent to repair shop for inspection and service in time to prevent more damage caused by long-term operation with malfunctions.

7. To protect your computer from interference, do not install a powerful mobile cordless phone system in your vehicle. When installing a conventional mobile phone, keep antenna and cable as far away from computer and its wiring harness as possible so that radio signals do not interfere with operation of computer.

Electronic engine maintenance

1. The electronically controlled gasoline engine management system has self-diagnosis and protection functions. Usually, ECU has a special fault self-diagnosis circuit. It constantly monitors operation of various sensors and some andactuators during engine operation. If a sensor or actuator malfunction is detected and it is operating normally, following protective measures are taken immediately:

A. With engine running, when ECU detects a malfunction signal from sensor and actuator, malfunction warning bar on instrument panel will light up to remind driver of malfunction of engine management system, and at same time, malfunction information will be displayed as a malfunction code. In order to ensure that vehicle can continue to move in event of a malfunction, driver must send vehicle in for repairs as soon as possible to avoid major damage.

B. Store contents of detected fault in computer's memory in form of fault codes. As long as car battery is not removed, detected trouble codes will always be stored in computer, even if car is running from time to time. When a failure occurs, computer will detect it in time and record it. During maintenance, service personnel may use certain methods to read fault codes stored in computer to provide an accurate basis for locating fault.

C. The protection circuit in ECU will replace operation of failed sensor in a predetermined manner so that ECU can continue to monitor engine operation and maintain vehicle's minimum driving performance. This feature is called failsafe. In this operating state, performance of engine will be more or less affected. In this state, computer of some models will automatically disable operation of some auxiliary devices on vehicle (such as air conditioners, audio system, etc.) Reduce load on engine.

2. Electronically controlled back-up engine microcomputer failure control system is when microcomputer in ECU fails, ECU controls fuel injection and ignition timing at a predetermined level as a back-up function to make machine continue drive.

3. The core of EC engine check is still check of oil circuit, circuit and seal (especially tightness of intake system).

4.Reading fault codes

Before reading DTC, engine must meet following basic conditions:

A. Battery voltage is over 11V

B. Throttle fully closed

C. Gearbox in park (automatic) or neutral

D. Turn off all auxiliary equipment (for example, air conditioners, stereos, lights, etc.)

Read fault code as follows:

A. Stop engine and turn off ignition.

B. Open connector cover to detectnear motor and connect two connectors TE1 (engine fault detection) and E1 (ground) with a wire according to names of connectors marked on cover. .

C. Turn ignition on and set it to ON position, but do not start engine.

D. Read fault code from engine warning light flashing pattern.

If control system is working properly and there is no fault code in ECU, fault indicator will flash continuously at a frequency of 5 times per second.

5. The way to clear fault code after fault is cleared is to disconnect EFI main fuse for 30 seconds or longer, or use A60PC intelligent version decoder to clear it.

6. The ECU has a learning function, but as soon as ECU's power circuit is cut off, data it stores while engine is running disappears.

7. When repairing electronic engine control system, if ignition is not turned off and plug is disconnected, battery is replaced or charged directly, an electromotive force will be generated and CEU will be damaged.

8. Before removing or installing an inductive sensor, ignition must be switched off so that its own electromotive force does not damage computer and cause new malfunctions.

9. When checking voltage of computer harness interface, you must use a high-resistance voltmeter, otherwise computer may be damaged.