Golf GTI L4-1781cc 1.8L SOHC (RD) (1987)
This graph, Fig. 4, shows an engine's basic air/fuel requirement. Notice that with CIS, the fuel flow is automatically correct for any volume of air flow
from idle to full load.
Fig. 5 Actual air flow chart
In actual use, the air-fuel requirements of an engine are not usually a straight line on a graph: this graph shows an engine's actual air/fuel requirement as a
broken line. The basic requirement of fuel and air is still shown as a solid straight line, Fig. 5.
At idle the engine runs slightly rich.
At part load the engine can run leaner for best fuel economy.
At full load a richer mixture is needed for maximum power.
Correction stages are built into the air cone to tailor the air/fuel ratio for an engine's actual requirements.