Fiat Bravo Service Manual page 378

Bravo >§i ** Engine
Fuel system
10.
BUTTERFLY CASING
The quantity of air drawn in is determined by the opening of the butterfly located at the start of the inlet
manifold. The butterfly casing is fixed to the inlet manifold by four bolts; the butterfly is operated by the
accelerator pedal by means of linkage which produces an opening system where in relation to the pedal
travel, small butterfly opening angles are produced with the pedal slightly pressed and greater opening
angles are produced with the pedal more depressed.
The air required to support the engine during idling and in load conditions with the butterfly valve
closed is regulated and by-passed exclusively by the engine idle speed actuator.
A special screw (1), makes it possible to adjust the butterfly closure to prevent interference with the sur­
rounding duct; this screw is not used for adjusting the idle as it is adjusted by fluxing in production and
should not be tampered with under any circumstances.
The flow of engine coolant arriving from the thermostat flows through the inlet and outlet ducts (3) and
(5) in the area of the butterfly valve has the aim of preventing condensation and the formation of ice
which could be produced in particular low external temperature and/or high humidity conditions.
The gases which flow from the engine crankcase are drawn into the inlet manifold downstream of the
butterfly through the PCV valve (4).
1. Butterfly valve adjustment and anti-tamper screw (not t o be tampered with)
2. Butterfly opening control levers
3. Attachment for engine coolant supply pipe
4. Attachment for engine crankcase vapour recovery and recirculation pipe
5. Attachment for engine coolant return pipe
6. Engine idle speed actuator
7. Butterfly valve position sensor
Copyright by Fiat Auto
27