1.3 MULTIJET 16V
(75 & 90 HP)
FIAT PUNTO TRAINING OUTLINE
Fiat Auto S.p.A.
After Sales Training
E.G.R. solenoid valve
Injection control unit
Heat exchanger
Exhaust manifold
Air inlet manifold
Operation
The injection control unit drives, with coolant temperature of more than 20°C and engine
speed ranging between 800 and 3,000 r.p.m., the E.G.R. solenoid valve through a square-
wave signal.
Variation of this signal allows the E.G.R. coil to displace a shutter, thus controlling the flow of
burnt gas from the exhaust manifold to the inlet manifold. Two results will thus be obtained:
less air is let in;
the combustion temperature is lowered (due to the presence of inert gas), thus reducing the
formation of NOx (nitric oxides).
The injection control unit is constantly informed about the amount of recirculated gas by the
data from the air flow meter. In fact, if a certain amount of air (Qam) is to be sucked with a
given engine speed, and the value provided by the air flow meter (Qar) is smaller, the
difference (Qgr) will be the value of the recirculated gas amount.
Qam - Qar = Qgr
Qam – Stored theoretic air amount
Qar – Actual air amount
Qgr – Recirculated gas amount
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© 2004 Fiat Auto S.p.A. – All rights reserved.
The atmospheric pressure signal is used when driving the E.G.R. solenoid valve to recognize
the high-altitude driving condition, so as to reduce the amount of recirculated gas and avoid
engine smokiness.
