How to adjust the clutch idle speed?

The engine should be idling, right? The following reposts are for your reference.

Idle speed adjustment is the most basic adjustment work in engine adjustment. Idle speed adjustment is directly related to the running state of the engine, the emission degree of pollutants and the economy.

The idle speed control system of electronically controlled fuel injection engine is much more complicated than that of carburetor engine. Its idle speed adjustment is divided into two parts: mechanical adjustment and computer automatic control. Maintenance personnel's mechanical adjustment of the idle system is the basis, and then the computer calculates according to the information provided by various sensors, selects the best control target, and instructs the actuator to complete it, so that the idle speed approaches the target value. Maintenance personnel's idle speed adjustment is the basic idle speed adjustment, at this time, the role of computer in control has been ruled out. The idle speed control valve (ISCV), the actuator of computer-controlled idle speed, should be in the initial reference position, which is mostly in the position of closing the bypass airway. For different models, this operating procedure also varies greatly due to structural differences. In order to facilitate the majority of automobile maintenance personnel to master, the following introduces the adjustment methods of basic idle speed of engines of common models.

1 Preparation before basic idle speed adjustment

E. Turn off the engine after adjusting the basic idle speed, and clear the fault code (35#) stored in the computer after disconnecting the ISCV circuit.

How to clear the fault code:

A. turn the ignitiON switch to the on position;

B, bridging the a end and the b end of the diagnosis seat;

C. Turn the ignition switch to the off position;

D take the EFI or ECM fuse out of the fuse box and insert it back after 30 seconds.

For vehicles that use the trip computer or air conditioning control panel to read and clear the fault code, you can operate the key according to the prescribed procedures.

The preparations for basic idle speed adjustment of various electronically controlled engines are basically the same, including the following steps:

A. Start the engine and preheat it to normal operating temperature.

B turn off other electrical equipment in the car, such as radio, air conditioner, lights, etc.

Keep the steering wheel in the middle position and the two front wheels in a straight line position. For vehicles with automatic transmission, the automatic transmission should be placed in P or N gear.

D. Make the throttle valve in the initial position: after determining that the throttle cable has a free amount, loosen the throttle limit screw first, so that the end of the screw is separated from the limit block. Then slowly screw in the limit screw so that it just touches the upper limit block, and then screw in the screw for half a turn. In this position, the throttle valve should be turned flexibly without looseness, and it will not get stuck when the throttle valve is suddenly closed. At this time, the cooperation between the throttle and the throttle body is more strict, and there is only a small light leakage gap in the light leakage method.

There is a large gap between the throttle valve and the throttle body of carburetor engine. Even if the throttle valve is closed, the gap is still large because all the air passes through the throttle valve at idle speed. For electronically controlled engines, when there is an idle screw in the intake air at basic idle speed, generally, the throttle can be kept at the initial position only by adjusting the idle screw to change the amount of idle air bypassing the throttle. Many maintenance personnel don't understand this, so when adjusting the idle speed, the throttle limit screw is screwed first, which changes the output signal of the throttle position sensor (TPS), resulting in wrong information to the computer. If there is no idle screw on the throttle body, the throttle limit screw can be adjusted to maintain the basic idle speed. At this time, the output signal of the throttle position sensor must be detected and adjusted to meet the requirements of the vehicle.

E. connect the tachometer. The vehicle engine tachometer (on the dashboard) is generally pointer-type, and its accuracy is poor. It is best to use a digital tachometer. The black contact pin is clamped on the ground wire, and the red contact pin is clamped on the EG end of the diagnosis seat or the "-"end of the primary side of the ignition coil.

F. Determine the basic ignition timing. When idling, use the timing lamp to detect the ignition advance angle, which shall meet the specified value of the vehicle. When adjusting the basic ignition timing of electronically controlled engine, the computer control of ignition advance angle should be cut off. If some models have an ignition advance control circuit near the distributor, the connector of the circuit can be removed. Some models have no ignition advance control line, so the control can be disconnected when crossing the diagnostic seat.

G. ensure that the engine works normally. If the engine is faulty or improperly adjusted, the basic idle speed cannot be adjusted. Usually, it can be preliminarily judged by experience whether the engine operates normally under various working conditions. You can also check whether the fault indicator light ("check") on the instrument panel goes out after the engine is running, and then connect a vacuum meter to the air inlet to observe whether the vacuum degree is between 57 kPa and 70 kPa (the minimum should be above 50KPa) when running at low speed, otherwise, you must first find the existing fault or poor adjustment problem, and then adjust the basic idle speed after troubleshooting.

H. If the engine is not overhauled, clean the dirt in the throttle body and the idle air bypass passage. Practice has proved that many poor idle speeds are mainly caused by dirt blocking channels or valves, which leads to lax closing.

2. Adjustment of basic idle speed of electronically controlled vehicles

The basic idle speed adjustment methods of electronically controlled engines with different models and different idle speed control systems are also different. The following are the basic idle speed adjustment methods of electronically controlled vehicles commonly used in China.

2. 1 GM and Daewoo.

A. At present, most GM and Daewoo cars are 12-hole (pin) diagnostic seats, so the engine should be started before the A-hole and B-hole are bridged. If it is the 16-hole diagnostic seat of OBD-II (the second generation on-board self-diagnosis system), it can span 5 holes and 6 holes.

B. After the engine is turned off, turn the ignition switch to the ON position (the engine is not running at this time) and wait for more than 30 seconds (at this time, the idle speed control valve will return to the initial position, usually the position where the bypass duct is closed).

C. Remove the connector of ISCV (Idle Control Valve) and the jumper wire on the diagnosis seat (ISCV will not work when the engine is restarted).

D. Start the engine and check that the idle speed should meet the basic idle speed value specified in the maintenance manual of this model (450 r/min-650 r/min for 2.0L engine; 2.5L engine is 550r/min-650r/min; 4.5L engine is 475 r/min-550 r/min; 5.0E engine is 450 rpm -500 rpm; 5.0LF engine is 400 r/min-450 r/min; 5.7L engine is 400r/min-450r/min), otherwise it should be adjusted. For vehicles with idle speed adjustment screws, the screws should be adjusted first. Generally speaking, screwing in the screw will reduce the rotational speed, and screwing out the screw will increase the rotational speed. If there is no idle speed adjustment screw, the throttle limit screw needs to be adjusted. At this time, just turn the limit screw to increase the speed to the basic idle speed. If the throttle does not move and the speed is higher than the basic idle speed, check whether the air inlet leaks, and test by blocking all vacuum lines. Finally, check whether the sealing rubber ring between the fuel injector and the intake manifold is aging and leaking.