Visual inspection (Opel Vectra B)

A leak in the area of the suction system lets in so-called by-product air. This is air that is not included in the calculations of the control unit and therefore significantly disrupts the preparation of the fuel-air mixture. The mixture becomes uncontrollably leaner. The disturbances are most noticeable in idle operation by fluctuations in the number of revolutions. In a loaded engine, this can even lead to the appearance of a ringing sound.

Check the air hoses for leaks. All hoses should be checked, from the thick air intake hose to the small vacuum hose to the pressure regulator.

In order of gaskets on injection valves; and also the suction channel flange gaskets?

Through unsealed sections, secondary air enters the intake system, i.e. air that the system cannot take into account, and therefore it significantly disrupts the preparation of the fuel-air mixture. The mixture becomes uncontrollably leaner, which results in engine malfunctions - mainly at idle.

Warm up the engine and run it at idle speed to check, open the hood. With the engine off, disconnect the lambda probe plug connection. This disables the lambda probe.

Aerosol starting fuel (eg, "Startpilot") deliberately water the gaskets between the flanges of the suction channels and other suspicious places.

If the engine speed changes after spraying a certain area, then it is not sealed.

Are there any leaks in the fuel lines?

Have you repeatedly connected and disconnected the wire connectors? Corrosion or unprofessional jerking can cause poor contact.

Carefully inspect the connectors of individual injection components. They can only be treated with contact spray, bending can cause malfunctions.