Audi A4 2001 Owner's Manual page 21

Injector
For the first time, an ICU injector ( I nverse C av-
ity U ndercut) is used, which has a dual needle
guide.
The advantage of this ICU geometry is a sig-
nificantly improved spray formation, espe-
cially in the part throttle range for small
injection quantities and short needle lift.
ICU seat geometry
Due to the improved spray formation through
the use of the ICU injector, it was possible to
reduce the exhaust emissions and the particle
values by up to 20 %.
ICU seat geometry
SSP255_041
Dual needle guide
Standard seat geometry
SSP255_042
21