Saab 9000 - Page 49

46 Technical Description
Fuel injection (contd.)
RPM
96
900
1260
1640
1830
2020
2400
2780
3160
3540
N
.,.
,.
0.71
0
tMO
.
0.12
,ao u1
2Cli20 UI
2400 O.M OM
27IO 0.14 O.N
I.N
3640 O.N
o.n
-
O.N
- O.N
60IO
0.17
IM
5440
1.00
1.0,3
Sa:zG
1.00
t~
Adaptation
(
~hoA
,~,W'
fve. \
""1
1
·
\-.v·,)
Due to shortage of space, only two pressure columns
are shown in the figure above.
The engine control module first calculates the fuel in-
jection duration on the basis of intake manifold pres-
sure and temperature.
Fuel injection duration is subsequently multiplied by
a correction factor which is dependent on pressure
and engine speed. It is obtained from the main fuel
matrix and must be used to correct the fuel injection
duration because the volumetric efficiency of the en-
gine changes with engine rpm.
By means of the closed loop, final correction then
takes place so that Lambda= 1 is obtained.
The closed loop can adjust the calculated fuel injec-
tion duration by
±
25%.
By means of the closed loop the engine control mod-
ule can change the correction factors in the main fuel
matrix so that good driveability, fuel consumption and
exhaust emissions will be obtained even when the
closed loop is not activated.
That is called adaptation.
0.80
0.78
0.82
0.81
0.81
0.84
0.84
0.86
0.88
KPa
Saab 9000
112
0.80
0.81
0.82
0.82
0.83
0.86
0.86
0.90
0.92