Contents: Gasoline engine ↓ Diesel engine ↓
Idle speed is the rotation frequency of the crankshaft when the accelerator pedal is released. This parameter is one of the critical ones, determining both the operation of the engine in general and the correct functioning of its various subsystems.
1. Check the air cleaner and all vacuum lines for proper installation and condition. Check for any signs of leaks in the air intake tract.
2. Set the parking brake and support the wheels with wheel chocks. Switch off all on-board electrical consumers and check that the ignition timing is set correctly (see chapter Engine electrical equipment).
3. The engine must be warmed up to normal operating temperature, which ensures automatic shutdown of fast idle.
4. Make sure the transmission is in position "P".
5. Only a remotely connected digital tachometer can provide the required accuracy of measuring the engine speed when checking its idle speed. Connect the device strictly in accordance with the manufacturer's instructions.
Gasoline engine
1. Connect the tachometer. Connect the tachometer tester probe to the "IG" (-) terminal of the diagnostic connector.
Caution: Do not allow the tachometer wire to touch ground, this may cause damage to the coil assembly.
2. Start the engine and increase the crankshaft speed to 1000 rpm; holding it for about 5 seconds. Release the gas pedal.
3. Read the tachometer readings and compare them with the requirements Specifications. If the idle speed does not meet the requirements Specifications, the fault most likely lies in the Electronic Idle Control System (ETCS). Idle speed on engines with fuel injection (EFI) is controlled by the ECM, there is no mechanical adjustment in this system.
Diesel engine
Minimum speed adjustment
1. Make sure that when the gas pedal is released, the fuel injection pump control lever touches the minimum idle speed adjustment screw (refer to the accompanying illustration). Otherwise, adjust the drive lever.
2. Start the engine, check the idle speed and compare the test results with the requirements Specifications.
3. To adjust, disconnect the fuel injection pump lever drive and set the minimum idle speed by turning the screw to a position corresponding to the middle of the specified range (refer to the accompanying illustration).
4. Tighten the adjusting screw lock nut and check the idle speed again.
5. Connect the control lever drive and adjust it if necessary.
Adjusting maximum speed
1. Make sure that when the gas pedal is depressed, the fuel injection pump control lever touches the maximum speed adjustment screw (refer to the accompanying illustration). Otherwise, adjust the drive lever.
2. Start the engine, fully depress the gas pedal, measure the maximum crankshaft speed and compare the measurement results with the requirements Specifications.
Note: Do not run the engine at maximum speed for more than 5 seconds. Adjust only when the minimum idle speed is adjusted.
3. To adjust, disconnect the accelerator rod, cut off the seal of the adjusting screw and loosen its lock nut with a special key. Set the maximum idle speed by turning the screw to a position corresponding to the middle of the specified range (refer to the accompanying illustration).
4. Tighten the adjusting screw lock nut, adjust the minimum idle speed, and check the maximum speed again.
5. Connect the accelerator rod and adjust the drive if necessary. Install a new seal on the adjusting screw.