Visual inspection (Audi 100 C4)

First, check the air ducts for leaks! You need to check all the hoses - from the thick air intake sleeve to the thin vacuum hoses.

Are the seals under the fuel starter valve and on the injection nozzles OK?; and also the intake manifold flange gaskets?

Leaky areas allow access to unaccounted air, i.e. air that is not accounted for by the air flow meter and therefore significantly interferes with the preparation of the mixture. The mixture is uncontrollably depleted. The consequence of this is engine malfunctions and uneven idling.

Is it possible to recognize a fuel line leak?

Have the wire ends been repeatedly separated and reconnected? Corrosion or poor handling may result in poor contact.

Examine the plugs of the individual components of the injection system. Do not bend the contact tongues, but treat them with contact spray.