ws6transam.org - Dan's Performance Page

ALDL Description information for these platforms:
2.8 Litre Chevrolet Multiport Fuel Injection System (1985 - 1986)
5.0 Litre Chevrolet Multiport Fuel Injection System (1985 - 1986)
5.7 Litre Chevrolet Multiport Fuel Injection System (1985 - 1986)
160 Baud ALDL operating characteristics:
Data Rate:      160 Baud (All)                     Level:  TTL
Refresh Rate:   1.25 Seconds                    Modes: 20K, 10K,
Stream size:    25 Bytes                                        3.9K, 500 Ohm
Byte Data Name Description
1 MW2 Mode Word 2
2 PROMIDA PROM ID (MSB)
3 PROMIDB PROM ID (LSB)
4 ISSPMP  IAC present motor position
5 COOLDEGA Coolant temperature, A/D counts
6 FILTMPH  Speed in Miles per hour
7 EGRDC  EGR duty cycle
8 NTRPMX  Engine speed in RPM 
    (25 RPM per bit)
9 ADTHROT  Throttle Position, A/D counts
10 CORRCL  Base pulse (fuel) closed loop correction
11 ADO2AF  Oxygen sensor minor loop filtered value
12 MALFFLG1 Malfunction flag word 1
13 MALFFLG2 Malfunction flag word 2
14 MALFFLG3 Malfunction flag word 3 
--(15) MALFFLG4 Malfunction flag word 4
15(16) MWFA1 Mode Word -- Fuel/Air
16(17) MAT  Manifold air temperature
17(18) MCUINST MCU input status word
18(19) LV8  Calculated load variable
19(20) BLM  Block learn multiplier
20(21) ALDLCNTR  Oxygen transition counter
21(--) SAREF+1 Unlimited spark advance 
(Multiply by 1/2.844 for degrees)
22 DISPFLOW Air Flow rate (Grams per sec.) MSB
23 DISPFLOW+1 Air Flow rate (Grams per sec.) 
LSB(1/256 grams per bit)
24 OBPINJ Injector base pulse width MSB
25 OBPINJ+1 Injector base pulse width LSB 
    (0.0153 Msec per bit)
Numbers in parenthesis indicate byte position in 1985 5.0 & 5.7 Litre data streams only.
 
Notes: 

   The 1985 data streams substitute ADBAT (battery voltage times ten) for LV8 as byte 18 of the data stream. 

   The 1986 data streams for the 5.0 Litre and the 5.7 Litre engines substitute a fourth malfunction flag (called MALFFLG4) between MALFFLG3 and MWFA1. 

   The 1986 data streams for the 5.0 Litre and 5.7 litre engines substitute OLDPA3 (Electronic spark cont. (knock counter input) for LV8 as byte 19 of the data stream. 

   The 1986 data streams for the 5.0 Litre and 5.7 litre engines do not contain the SAREF byte(s). 

   The 1986 data 5.0 litre and 5.7 litre engines also have an 8192 baud data stream that contains 64 bytes of data.  This stream is updated once every 0.1 seconds.   The definition of the flags for the 8192 baud data streams is the same as for the 160 baud data streams. 

160 Baud Mode Words & Status Flag Descriptions
Byte Name BCD Description
MALFFLG1 MALF FLAG WORD 1 
Bit     Code    Description 
0       24      Vehicle speed sensor 
1       23      MAT sensor low 
2       22      Throttle position sensor low 
3       21      Throttle position sensor high 
4       15      Coolant sensor low temperature 
5       14      Coolant sensor high temperature 
6       13      Oxygen sensor 
7       12      No reference pulse (engine not running)
MALFFLG2 MALF FLAG WORD 2 
Bit     Code    Description 
0       42      Electronic spark timing monitor error 
1       41      Cylinder select error 
2       35      Not used 
3       34      Mass air flow sensor low 
4       33      Mass air flow sensor high 
5       32      Exhaust gas recirculation diagnostic 
6       31      Not used 
7       25      Manifold air temperature high
MALFFLG3 MALF FLAG WORD 3 
Bit     Code    Description 
0       55      ADU error 
1       54      Fuel pump voltage 
2       53      Over voltage 
3       52      CAL pack missing 
4       51      PROM error 
5       45      Oxygen sensor rich 
6       44      Oxygen sensor lean 
7       43      Electronic spark control failure
MW2 Mode Word 2 (160 BAUD) 
Bit     Description 
0       Road speed pulse occurred (6.25 msec check) 
1       ESC failure (not used in 1986) 
2       Reference pulse occurred (6.25 msec check) 
3       Diagnostic switch in factory test position (3.9 K) 
4       Diagnostic switch in diagnostic position (0 ohms) 
5       Diagnostic switch in ALDL position (10 K ohm) 
6       High battery voltage-disable MCU solenoid discretes 
7       Air meter pulse occurred (6.25 msec check)
MWFA1 FUEL AIR MODE WORD 1 (160 BAUD) 
Bit     Description 
0       Fourth TPS forced O/D disable 
1       Learn control enable flag (1 = enable) 
2       Low battery (1 = low) 
3       Prop. step taken flag (1 = rich, 0 = lean) 
4       Vehicle speed sensor failure 
5       EECC clow O2 rich/lean flag 
6       Rich/Lean flag (1 = rich, 0 = lean) 
7       Closed Loop flag (1 = Closed Loop, 0 = Open Loop)
MCUINST MCU INPUT STATUS WORD 
Bit     Description 
0       Park/Neutral mode = 1 
1       In cruise (or low A/C head pressure) = 1 
2       TCC locked / or overdrive enables = 1 
3       Excessive power steering pressure = 1 
4       100 msec old 4th gear (set/cleared in TCC) = 1 
5       Not in 3rd gear/overdrive = 1 
6       4th gear switch closed = 1 (0 = in 4th gear) 
7       A/C requested = 0

 
 
 1986 Chevrolet 5.0 & 5.7L Port Fuel Injection (TPI) 8192 Baud ALDL data stream description
BYTE DATA DESCRIPTION
1 PROMIDA  First PROM ID word (MSB)
2 PROMID+1 Second PROM ID word (LSB)
MALFFLG1 Malfunction word 1
4 MALFFLG2 Malfunction word 2
5 MALFFLG3 Malfunction word 3
6 MALFFLG4 Malfunction word 4
7 MALLFLG5 Malfunction word 5
8 COOLDEGA  Coolant temperature (See page 3)
9 COOLTSU  Coolant temperature of start up (Same units as 8)
10 ADTHROT Throttle position sensor (1/2.56% / bit)
11 NTRPMX  Engine speed (RPM)
12 NEWRFPER Time between reference pulses (MSB)
13 NEWRFPER+1 Time between reference pulses (LSB)
14 FILTMPH Vehicle speed in MPH (MSB)
15 FILTMPH+1 Vehicle speed in MPH (LSB)
16 NVATIO  RPM/MPH
17 ADO2AF Oxygen sensor variable
18 ALDLCNTR  Oxygen sensor rich/lean transitions
19 CORRCL Base pulse (fuel) C.L. fine correction
20 BLM  Base pulse (fuel) C.L. course correction
21 BLMCELL Current block learn multiplier
22 INT  Closed loop integrator
23 ISSPMP  Idle speed sensor present IAC motor position
24 ISSTCD  Idle speed steps commanded direction
25 ISESDD Desired idle speed RPM/12.5
26  FILTLVB  Filtered load variable  (Air flow * RPM)
27 ADTESTCH  AD test channel (nominal: 128)(Acceptable: 118-137)
28 LVB12  Load variable 12.5 msec old
29 MAT  Manifold air temperature
30 ADMAT  Manifold air temperature
31 EGRDC EGR duty cycle
32 PURGEDC  Charcoal cannister purge duty cycle
33 FANDC Engine cooling fan duty cycle
34 ADBAT Battery voltage (A/D counts: 0.1Volt/bit)
35 PPSW  fuel pump power supplied
36 DISPFLOW  Mass Air Flow variable in grams per second (MSB)
37 DISPFLOW+1 Mass Air Flow variable in grams per second (LSB)
38 AIRFLOW Unlimited mass air flow (not defaulted)
39 SAP Total spark advance (w.r.t. TDC) (MSB)
40 SAP + 1 Total spark advance (w.r.t. TDC) (LSB)
41 SAREF Spark Advance w.r.t. ref. pulse (MSB)
42 SAREF+1 Spark Advance w.r.t. ref pulse (LSB)
43 OLDPA3  Electronic spark control (knock) input
44 NOCKRTD  Electronic spark control (knock) output
45 OBPINJ  Injector base pulse width (MSB)
46 OBPINJ+1 Injector base pulse width (LSB)
47 FAVAL Total fuel/air value (MSB)
48 FAVAL +1 Total fuel/air value (LSB)
49 ACUMFUEL Total fuel delivered (MSB)
50 ACUMFUEL+1 Total fuel delivered (LSB)
51 ACUMDIST Total distance traveled (.0005mile/bit)
52 TIME Engine run time (seconds) (MSB)
53 TIME+1 Engine run time (seconds) (LSB)
54 MW2 Bit status word - ALDL test condition
55 MCUINST MCU instruction status word
56 FMDBYTE1 FMD status word
57 MW1 Mode word 1
58 NVMW NV mode word
59 DNEEMW Drive/neutral mode word
60  ALCLMW ALDL mode word
61  AIRMW AIR mode word
62  SDMW Serial data mode word
63  MWFA1 Mode word (fuel/air)

 
Scaling of the Double-byte words:
WORD DEFINITION SCALING COMMENTS
NEWRFPER 
NEWRFPER+1
Time between reference pulses 0-65535 Combine words 
FILTMPH 
FILTMPH+1 
Vehicle speed  MPH 
MPH/256
 Whole part 
 Fractional part
FLTLV8 
FLTLV8+1
Calculated Load   LV8 
LV8/256
Whole part 
Fractional part
DISPFLOW 
DISPFLOW+1
Mass Air flow value 
(0 if malf 33/34)
g/sec. 
g/sec. 
Whole part 
 Fractional part
SAP 
SAP+1 
Unlimited spark advance w/respect to TDC deg*2.8444  range +/- 32768
SAREF 
SAREF+1
Unlimited spark advance 
w/respect to TDC
deg*2.8444 range +/- 32768
OBPINJ 
OBPINJ+1
Old injector base pulse width  0.0153 msec  range 0-65536 
per count
FAVAL 
FAVAL+1
Fuel/air ratio  6553.6/E  E = A/F ratio
ACUMFUEL 
ACUMFUEL+1
Accumulated fuel    running total of fuel counts
TIME 
TIME+1
Engine run time in seconds secs from power up range 0-65536

 
8192 Baud data stream Mode Word bit descriptions for '86 5.0 & 5.7L TPI:
Malfunction Flag BCD byte name Definition
MALFFLG1 Bit     Code    Definition 
0       23      MAT sensor low 
1       22      Throttle sensor position low 
2       21      Throttle sensor position high 
3       16      Not used 
4       15      Coolant sensor low temperature 
5       14      Coolant temperature low sensor 
6       13      Oxygen sensor 
7       12      No reference pulses
MALFFLG2 Bit     Code    Definition 
0       35      Not Used 
1       34      MAF sensor low 
2       33      MAF sensor high 
3       32      EGR diagnostics 
4       31      Not Used 
5       26      Not Used 
6       25      MAT sensor high 
7       24      Vehicle Speed Sensor
MALFFLG3 0       51      PROM error 
1       46      Not Used 
2       45      Oxygen sensor rich 
3       44      Oxygen sensor rich 
4       43      ESC failure 
5       42      EST monitor error 
6       41      Cylinder select error 
7       36      Burnoff diagnostics
MALFFLG4 Bit     Code    Definition 
0       63      Not Used 
1       62      Not Used 
2       61      Not Used 
3       55      Not Used 
4       54      ADU error 
5       53      Fuel pump voltage 
6       52      Over voltage 
7       51      CAL pack missing
MALFFLG5 Bit     Code    Definition 
0       75      Not Used 
1       74      Not Used 
2       73      Not Used 
3       72      Not Used 
4       71      Not Used 
5       66      Not Used 
6       65      Not Used 
7       64      Not Used

 
8192 Baud data stream Mode Word bit descriptions for '86 5.0 & 5.7L TPI:
Name Description
MW2 Mode Word 2: 
Bit     Definition 
0       Overdrive (0 = off, 1 = on) 
1       MALF 14 or 15 this start up 
2       Reference pulse occurred (6.25 msec check) 
3       In ALDL mode 8192 mode 4 (1 = in mode 4) 
4       Diagnostic switch in diag. position 
5       Diagnostic switch in ALDL position 
6       High bttery voltage - disable MCU solenoid disabled 
7       Shift light (1 = on)
MCUINST MCU instruction word 
Bit     Definition 
0       Park/Neutral status (1 = P/N) 
1       Not in 3rd gear (1 = not in 3rd) 
2       Overdrive request (1 = requested) 
3       Excessive power steering pressure (1 = high pressure) 
4       EGR diagnostic switch closed (1 = EGR switch closed) 
5       Trans. converter clutch (1 = TCC locked) 
6       Air Condition high pressure (0 = high pressure) 
7       Air Conditioning (0 = A/C requested)
FMDBYTE1 Bit     Definition 
0       Park/Neutral switch (0 = drive) 
1       3rd gear 
2       4th gear 
3       Power steering (1 = cramp) 
4       Not Used 
5       EGR diagnostic 
6       Air Conditioning hi-pressure 
7       Air Conditioning requested (1 = A/C requested)
MW1 Mode Word 1 
Bit    Definition 
0      Advance Flag (0 = ADV, 1 = Retard) 
1      Check Engine Light delay flag 
2      Interrupt service execution exc. 6.25 msec 
3      Fan on disabled by PID 
4      TCC road speed 1st pulse flag 
5      Air cond. clutch flag (0 = A/C clutch on) 
6      Bypass check enable 
7      Engine running flag ( 1 = running)
NVMW Bit   Definition 
0      O2 sensor ready (1 = ready) 
1      Closed loop timer timed out (1 = timed out) 
2      Not used 
3      Improper shutdown (1 = yes) 
4      CCP startup timer expired (1 = expired) 
5      IAC kickdown enabled ( 1 = enabled) 
6      KWARM kickdown enabled (1 = enabled) 
7      MALF 42 failed (EST monitor) (1 = failed)
DNEEMW Bit   Definition 
0     Overdrive on (1 = on) 
1     1st gear direct (1 =on) 
2     1st upshift OK (look-ahead) ( 1 = ok) 
3     4th gear (1 = 4th gear) 
4     1st gear overdrive (1 = overdrive) 
5     Downshift/off request (1 = request) 
6     Upshift/on request (1=request) 
7     Overdrive active (1 =request)
ALDLMW ALDL Mode Word 
Bit   Definition 
0      ALDL reset 
1      Not Used 
2      Field Service mode 
3      First C/L pass-thru field service mode (1 = done) 
4      Field service O2 transition 
5      One second flag 
6      200 MSEC toggle bit for 2.5 HZ flash rate 
7      Pullup resistor for coolant (1 = 4K)
AIRMW Air mode word 
Bit    Definition 
0      100 MS old CCP purge on flag (1 = on) 
1      Air management (0 = air diverted) 
2      Air switched port (1 = switched) 
3      Not Used 
4      Skip burnoff due to >17 Volts (1 = skip) 
5      D.E. QSEQ (1 = on) 
6      Burn off air meter (1 = burn off) 
7      Decel enleanment (1 = enleanment)
SDMW Serial data mode word 
Bit   Definition 
0      Expecting first 160 BAUD interrupt (1 = yes) 
1      Expecting second 160 BAUD interrupt (1 = yes) 
2      In 8192 Mode (1 = yes) 
3      Locked in 8192 mode (1 = yes) 
4      Not used
5      Not used 
6      Not used 
7      Not used 
MWFA1 Mode Word Fuel/Air 
Bit Definition 
0 Nor used 
1 Learn control enable flag (1 = enable store) 
2 Not used 
3 Not used 
4 Vehicle speed sensor failure 
5 EECC clos O2 Rich/Lean flag 
6 Rich-lean flag (1 = rich) 
7 Closed loop flag (1 = closed loop)

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