TECHNICAL NOTES ON THE EEC-IV MCU - Auto diagnostics

EEC TABLES
Parameter Variable Variable A9L
Accel Enrichment Fuel [lb/min] Throttle Rate [Deg/sec] ECT 01CB
Startup Fuel [A/F Ratio] ECT Time 7C40
Base Fuel [A/F Ratio] ECT Load 7BF0
Injector Timing [Crank Degrees] RPM Load 7160
Load Injector Firing Order Injector to Fire 71B9
Base Spark [Deg BTDC] RPM Load 7574
Altitude Base Spark [Deg BTDC] RPM Load 75C4
Limp Mode Spark Table [Deg BTDC] RPM Load 7614
Injector Output Port
Borderline Detonation Spark
Injector Port 71B1
Borderline Compensation ECT ECT
Borderline Compensation ACT ACT
Borderline Compensation
Acceleration Fuel Time Constant
Exhaust Pulse Delay
HEGO Amplitude
HEGO Bias
Engine Torque
Engine Frictional Torque
Lambda Lambda
Table 20: EEC Tables
A9L Constants & Locations
Eectch98-Part2.fm
Below is a description of each parameter stored in the EEC computer -- so far as we know it.
For a more detailed description of how the data is actually stored in the EEC, go to the section
titled “A9L Tables” on page 39 and “A9L Table Format Explanation” on page 43.
THROTTLE RATE DEG/SEC
E
C
T
15 33 48 63 77 90 110 125
200 1.5 1.5 2.0 3.0 4.5 8.0 12.0 18.0
150 1.5 1.5 2.0 3.0 4.5 8.0 12.0 20.0
100 2.0 2.0 3.0 4.5 8.0 12.5 18.0 29.0
50 4.0 5.0 6.0 8.0 12.5 17.0 25.5 34.0
30 5.0 8.0 10.0 12.0 16.5 21.0 27.0 45.0
0 12.0 14.0 16.0 18.0 26.0 30.0 38.0 55.0
-30 21.0 23.0 26.0 28.0 31.0 34.0 39.0 56.0
Table 21: Accel Enrichment Fuel [lb/min]
The Accelerator Enrichment Fuel Table provides an operation similar to the "accelerator
pump" in a carburetor. It gives amounts of extra fuel to add based on how fast the throttle
is being depressed and modifies that by the engine temperature. For the A9L, the table is
located at 71CB hex, is 8 x 7 in size, the values being stored as unsigned, single byte values
in a two binary point representation (i.e. the smallest resolution is .25 lb/min). To get
the values below, the value of each corresponding byte will need to be divided by four or
multiplied by .25.
ENGINE COOLANT TEMPERATURE o F
-30 0 30 60 90 120 150 180 210 240
Table 22: Startup Fuel Ratio
EEC-IV Technical Notes: Software 28 last edited: 9/29/98