Ford Workshop Service and Repair Manuals

The fuel additive tank is located behind the fuel tank and is attached to the crossmember. The fuel additive pump unit forms one complete assembly with the tank and is located in the fuel additive tank.

The fuel additive pump unit and fuel additive tank can only be renewed as one complete unit.

The volume of the fuel additive tank is 1.8 l and is designed for an total driving distance of 60,000 km. The fuel additive must therefore be topped up in accordance with maintenance instructions.

After filling the fuel additive tank, the software of the fuel additive control unit must be reset. This can be done with WDS or manually with the tank flap switch if no fault code is present.

Fuel additive pump unit

The fuel additive pump is a positive displacement pump (reciprocating pump) and, in response to commands from the fuel additive control unit, delivers a metered quantity of fuel additive to the injector on the top of the fuel tank via a short fuel pipe; the injector then injects the additive into the fuel tank.

The piezo sensor records the fill level of the fuel additive in the fuel additive tank and transmits this information to the fuel additive control unit.

Its other task is to determine any change in the viscosity of the fuel additive as a function of ambient temperatures; this may result in the metered quantity of fuel additive having to be corrected.

If the fill level of the fuel additive in the fuel additive tank falls below a certain limit, the engine system fault warning lamp in the instrument cluster will switch on.

If the fuel additive tank becomes empty, the Malfunction Indicator Lamp (MIL) will light up.

Injector

The injector is connected to the fuel additive tank by means of a fuel pipe.

The build up of pressure in the fuel pipe caused by the fuel additive pump causes the non-return valve in the injector to open, thus feeding fuel additive into the fuel tank.

Tank flap switch

The tank flap switch consists of a reed contact on which a magnet located in the tank flap acts.

When the tank flap is opened, this causes the tank flap switch to shut and a signal is then sent to the fuel additive control unit indicating that the fuel tank is being filled up.

The fuel additive control unit then goes into "sleep" mode until the tank flap is closed again and "sleep" mode is cancelled by the tank flap switch.

The next time the ignition is switched on the current fuel level is determined and compared with the fuel level before the tank was filled; the difference between the two measurements is calculated.

Using the calculated difference between the two quantities of fuel as a base, the fuel additive control unit calculates the quantity of fuel additive to be added and activates the fuel additive pump.

Activation/metering is done from a vehicle speed of 40 km/h, or 4 minutes after the engine was first started after re-fuelling if the specified vehicle speed has not been reached.

Fuel additive

A metallic catalyst consisting of cerium and iron is used in the fuel additive. Because of it, the soot particles can be burned off faster and the combustion occurs at a lower temperature.

Each time after the fuel tank is filled, a metered quantity of fuel additive is injected into the fuel tank where it mixes with the fuel.

When fuel mixed with low concentrations of fuel additive burns in the cylinder, cerium oxide particles bind with the soot particles.

The homogeneously bound cerium oxide/soot particles are then filtered out by the particulate filter, where they become embedded.

As a result, the oxidation process during regeneration can be accelerated considerably by the large number of contact points between the cerium oxide catalyst and the soot particles and can also take place at a lower temperature.