Periodically check the routed hoses and their connections for proper fit and fatigue cracks:
- Vacuum hose to the absolute pressure sensor.
- Brake booster vacuum hose.
- Are all engine ventilation hoses in good condition? Or are they clogged, dirty or oily?
- Are the fuel lines sealed?
- Are the connections and pressure regulator tight, and...
- ...the drain line from the pressure regulator? Look for cracks and leaky connections.
- If you need to "pull" the wire plug during work under the engine hood, you can then provoke a weakening of the contact. As a preventative measure, treat the terminals with contact spray. In "serious cases" you can "sensitively" bend the contact tabs.
Additional air - instills uncertainty in the operation of the RCM
Loose spots in the intake system lead to uncontrolled additional air. This instills uncertainty in the PCM and leads to incorrect results, for example, when preparing the fuel-air mixture: the injectors supply the engine with too little fuel. The consequence: the fuel mixture becomes uncontrollably lean. "Unsecured" engines in the partial load range tend to "leanness jerks" of the fuel mixture and at full load you can also hear "detonation knocks". The symptoms described are, among other things, "external defects": over time, they can lead to more expensive consequences (e.g. burnt piston crowns, piston seizure, valve defects) and the like). To protect your Mondeo from all this, the cylinder block of Duratec engines "monitors" the knock sensor. As soon as the noises become "unhealthy", the sensor reports this to the PCM. The transmission control unit sets the "detonation" cylinder further to a late ignition moment. Attentive drivers note this intervention: the Mondeo reacts much more coolly to pressing the gas pedal. In order for the knock sensor to be "inoperative", it is necessary to inspect the intake system more often.