Mixture Adaptation - Lotus TURBO ESPRIT Service Manual

SECTION LD Page
7 3
LD.
6
-
MIXTURE ADAPTATION
The system so far described provides a fuel/ air mixture suitable for normal running.
Various supplementary devices are required i n order to adapt the mixture strength
for differing climatic, transient and emissions related conditiom
.
These components
include those providing enriched mixture strength for cold starting and running,
fuel cut-off on overun, and adjustment of mixture to achieve minimal harmful
emissions.
LD. 7
-
COLD
START INJECTOR
When starting a cold engine, the cranking speed induces very low air flow with
resulting low fuel delivery to the injectors. The additional fuel necessary for
cold starting i s supplied by the cold start injector only at cranking, and for a
maximum duration of between
0.1
and
8.0
seconds dependant on coolant temperature.
Auxiliary
Cold Start Injector
Air
Valve
I
/
Fuel
l
njector
Cold Start
The single cold start injector i s fitted into an air rail running alongside the fuel
injector air stream rail on the inlet manifold. Connecting passages join this air
r a i l with each intake tract. A hose from the auxiliary air valve allows a flow of
air to be drawn around the cold start injector on engine cranking to finely atomise
the fuel sprayed from its nozzle.
'
The cold start iniector i s a solemid valve supplied with fuel at primary pressure
from the fuel distributor, and i s opened by a current supplied via, and for
a
time
period governed by the thermal time switch.