TECHNICAL NOTES ON THE EEC-IV MCU - Auto diagnostics

T
I
M
E
45.00 0 0 0 0 0 0 0 0 0 0
35.00 1.000 1.25 0.875 0.500 0.375 0.875 0.875 0.250 0.500 1.000
25.00 1.250 1.500 1.125 1.000 1.000 1.250 1.250 0.875 1.000 1.250
15.00 1.625 1.625 1.500 1.375 1.250 1.375 1.375 1.125 1.375 1.625
10.00 2.250 2.125 2.125 1.875 1.875 1.875 1.875 1.250 1.875 2.250
5.00 2.750 2.750 2.375 1.875 1.875 1.875 1.875 1.500 1.875 2.750
3.00 2.875 3.625 2.625 1.875 1.875 1.875 1.875 1.625 1.875 2.875
0.00 3.375 4.125 3.000 1.875 1.875 1.875 1.875 1.375 1.875 3.375
Eectch98-Part2.fm
The Startup Fuel A:F Ratio Table sets the startup fuel mixture enrichment based on
the engine temperature -- analogous to the choke function of a carburetor. The mixture
is additionally modified by the time the engine has been operating. For the
A9L, this data table is stored at 7C40. It is a 10 x 8 table with unsigned, single
byte values stored in three binary point format (.125 resolution). To retrieve the
information from the byte values, they must be divided by 8.
L
O
A
D
%
ENGINE COOLANT TEMPERATURE o F
-30 0 30 60 90 120 150 180 210
90 10.500 10.500 12.500 12.500 12.750 13.125 13.500 13.500 13.500 13.500
80 11.250 11.250 12.7500 12.750 13.125 13.500 13.750 13.750 13.625 13.500
70 12.125 12.125 13.500 13.500 13.875 14.375 14.125 14.250 13.625 13.625
55 12.750 13.875 14.250 14.375 14.875 14.875 15.250 16.000 16.000 15.000
40 13.625 14.375 14.375 14.375 14.875 15.250 15.250 16.000 16.000 14.750
30 14.125 14.250 14.250 14.375 14.500 14.750 14.750 15.250 15.250 14.375
15 17.625 17.625 17.000 16.625 16.500 16.375 16.000 15.250 15.250 15.250
5 17.875 17.875 17.625 17.250 16.625 16.375 16.000 15.250 15.250 15.250
Table 23: Base Fuel A:F Ratio
Base Fuel A:F Ratio: ECT vs. Load. Located at 76F0 (for the A9L), it is a 10 x 8 table of
single, unsigned binary values stored in three binary point format (divide by 8).
RPM
L
O
A
D
%
Table 22: Startup Fuel Ratio
420 420 420 420 420 420 420 464 464 464
420 420 420 420 420 420 420 464 464 464
380 380 380 380 380 380 420 420 464 464
352 352 352 352 352 380 400 400 400 400
352 352 352 352 352 352 352 352 352 352
352 352 352 352 352 352 352 352 352 352
352 352 352 352 352 352 352 352 352 352
352 352 352 352 352 352 352 352 352 352
Table 24: Injector Timing
The Injector Timing Table is expressed in crank degrees and is modified by rpm and
load. The A9L values are located at 7160 hex in a 10 x 8 table, each data value
being one unsigned byte. The value stored has the two LSB places shifted off so that
the binary value must be multiplied by 4 to recover the data (i.e. the minimum resolution
is 4 crank degrees and, I suppose, the maximum value possible is 2048).
Injector to Fire
1 3 7 2 6 5 4 8
Table 25: Injector Firing Order
The Load Injector Firing Order Table is stored at hex 71B9 in the A9L and is the 302
EEC-IV Technical Notes: Software 29 last edited: 9/29/98