e. Deceleration and CUT-OFF

e. Deceleration and CUT-OFF

The fuel cut off fucntion (cut-off) depends on the closure of the contact (1) in the idle control motor, the temperature of the coolant and the engine speed.

The first two conditions necessary for activating the cut off function are:

• - temperature of the coolant about 40° C,
• - engine speed above around 1800 rpm.

If the above conditions exist during deceleration, when the idle contact closes (1 - butterfly closed) terminal 8 for the control unit goes to earth and the injection of fuel is interrupted via terminal 35.

In addition to cutting off the fuel the control unit activates a special ignition curve with an advance known as "release".

The cutting off of the fuel injection and the special advance curves are operational until the engine reaches a speed of around 1500 rpm and below this level the injection impulses must be activated to prevent the engine from cutting out.

When the injection is restored, the control unit implements a fuel enrichment strategy so that the film of petrol reforms on the inlet manifold.