Jetta can't get off at idle speed after changing the throttle.

Unstable idle speed of Volkswagen Jetta is the most common fault in engine maintenance. The direct cause of engine idling instability refers to the dirty, worn and incorrect installation of mechanical parts, which leads to the change of single cylinder power, resulting in the imbalance of cylinder power and unstable engine idling;

The indirect cause of engine idling instability refers to the abnormality of engine electronic control system, which leads to poor combustion of mixed gas, making it difficult to balance the power of each cylinder and making the engine idling unstable.

1. Idle switch is not turned off.

Diagnostic method: Turn on the air conditioner and turn the steering wheel when idling. The engine speed does not increase, which can prove this fault.

Troubleshooting: Adjust, repair or replace the throttle position sensor.

2. Idle speed control valve (ISC) is faulty.

Diagnostic method: Check the starting sound of the idle control valve. If there is no starting sound, the idle control valve is faulty.

Troubleshooting: Clean or replace the idle speed control valve, and set the idle speed with a special decoder.

3. The air inlet pipe leaks.

Diagnosis method: If you hear the smell of air leakage in the intake pipe, it proves that the air intake system is leaking.

Troubleshooting: Find the leakage, reseal or replace the phase parts.

4. The fuel injector leaks or is blocked.

Diagnostic method: Use a stethoscope to check whether the fuel injector makes clicking sound or measure the fuel injection quantity of the fuel injector. If the injector does not click or the injection quantity exceeds the standard, the injector is faulty.

Troubleshooting: Clean the injectors and check the fuel injection quantity of each injector to ensure that there is no blockage or leakage.