- Brake booster vacuum hose.
- Fuel lines.
- Pressure regulator.
- The return fuel line that comes from the pressure regulator.
Further verification:
Frequent disconnection and connection of cable connectors may cause poor contact. Treat the contacts with a special aerosol for treating electrical contacts. Contact tabs should be bent only as a last resort, and this should be done carefully.
If you want to check if the engine is sucking in extra air (this is often seen with idle problems), do the following:
1. Check the vacuum hoses for cracks and tightness. Check all hoses that are connected to the intake manifold. This includes the hoses that go to the brake booster, fuel pressure regulator, and fuel regeneration solenoid valve.
2. Warm up the engine and let it idle. Open the hood.
3.Spray the throttle body, the flanged seals of the intake ducts and the pipes leading to the unit, which are controlled using vacuum, with an aerosol can of starting liquid. To do this, disconnect the detachable connections of the oxygen sensors.
4. If the engine speed changes when spraying any of the listed places, this means that you have found a loose spot.
[The original article is posted on the resource: AUDImanual.ru]