New MPI Engine Control System (GROUP 01, NO. 93-02)
Reference number: GROUP 01, NO. 93-02
NEW MPI ENGINE CONTROL SYSTEM
TECHNICAL SERVICE BULLETIN
NEW MPI ENGINE CONTROL SYSTEM
Model(s): 1993 Audi 90
Group: 01
Bulletin No.: 93-02
Date: April 15, 1993
SERVICE INFORMATION
This bulletin applies to cars with Engine Control Module (ECM) (J192), Part No. 8AO 906 266B.
Vehicles with this ECM will be equipped (as a running change in production) with a new Mass Air Flow sensor (without CO-potentiometer) and new Oxygen sensors.
The new control system can be identified as follows:
- The new Mass Air Flow (MAF) sensor has 3-wire harness connector.
- The old Mass Air Flow sensor has a 4-wire harness connector.
This bulletin highlights the important technical changes.
The new ECM has several additional and expanded functions:
- Function 01: Engine Control Module version, displaying
- Function 02: Diagnostic Trouble Code (DTC) chart
- Function 04: Engine basic adjustment
- Function 07: ECM coding
- Function 09: Read individual test values, can still be displayed but does not contain useful information.
ENGINE CONTROL MODULE VERSION, (CODE NUMBER) DISPLAYING, USING VAG 1551 SCAN TOOL
REQUIREMENTS
- Diagnostic Trouble Code (DTC) memory, activated.
Activate and then erase DTC memory, continue to let engine idle.
Display will show the following:
Press 0 and 1 buttons to select function 01 "Control Module version activated".
Display will show the following:
Press Q button to enter input.
Display shows ECM number and code as follows:
Code breakdown:
- ECM identification number (8A0 906 266 B): actual ECM version
- Engine type: V configuration, 6 cylinder
- Engine displacement: 2.8 liter
- Number of valves per cylinder: 2
- Fuel system type: MPI (multi-point injection)
- Software version of ECM: V6...= EPROM-status of ECM
- Hardware and software version of ECM: D...= program status of ECM
- Coding variants (country codes): Coding 000.
- VAG operating number: WSC... (the numeral portion is read into the VAG 1551)
If the ECM number cannot be displayed:
Disconnect and re-connect ECM to see if intermittent condition is eliminated.
If NO
Replace control module.
An erroneous ECM code number can lead to:
- Vehicle handling problems
- Increased fuel consumption
- Transmission service life reduced
- Storage and observance of Diagnostic Trouble Codes that do NOT exist for this vehicle
- Functions NOT listed such as Oxygen sensor control, EVAP solenoid valve triggering
- High speed not attainable
To code ECM, refer to ENGINE CONTROL MODULE (ECM) CODING.
Press --> button.
Display will show the following:
FUNCTION 02 DIAGNOSTIC TROUBLE CODE (DTC) TABLE
The DTC table includes diagnosis of the EVAP solenoid valve.
As a result of the learning capability of the Oxygen sensor control system, the CO-potentiometer (mounted on the mass air flow sensor) has been deleted and in turn the CO-potentiometer diagnostic has also been deleted.
| VAG 1551 Display | Possible Cause | Possible Effects | Corrective Measures |
|---|---|---|---|
01243
Intake Manifold Change-Over Valve (N156)
|
Short to groundin N156 or in the wiring between N156 and J 192 ECM. J192 faulty | Valve does not open (Voltage supply problem) Valve always open (torque malfunction) | Check N156 Eliminate open circuit or short Replace J192 and perform coding |
| -One of these displays will appear in addition to the display code. | -- | -- | -- |
FUNCTION 04 ENGI NE BASIC ADJUSTMENT, USING VAG 1551 SCAN TOOL
Display Group 0 0, channel 9 NO LONGER shows the CO adjustment value, instead IT NOW shows the learning requirement adaptation.
If the display is 0:
Adaptive learning in the closed and partially open throttle position is in pr ogress.
If the display is 3 or greater
Adaptive learning for idle speed has been completed.
- If the ECM is removed or the battery is disconnected, all learned values in the ECM are erased. Shortly thereafter rough idling can occur. In which case let the engine idle for a few minutes until the learning requirement is 2 or greater. Deviations displayed in channel 8 are valid only when the idle speed adaptive learning has been completed.
- Then, roadtest the vehicle to establish learning in the other speed ranges.
FUNCTION 07 ENGINE CONTROL MODULE (ECM), CODING, USING VAG 1551 SCAN TOOL
If NO or if the ECM was replaced, code the ECM as follows:
Activate and then erase Diagnostic Trouble Code (DTC).
Start engine and let idle.
Display will show the following:
Press 0 and 7 buttons to select function 07 "coding Engine control module".
Press Q button to enter input.
Display will show the following:
Input the correct code for this vehicle using the buttons/code variants shown in the ECM CODE CHART .
Display will show the following:
Press --> button.
Display will show the following:
Display will show the following:
Press 0 and 6 buttons to select function 06 "Output ended.
Press Q button to enter input.
Display will show the following:
| Coding variations (country code) | Transmission Type | is equipped with: |
|---|---|---|
| 003 | Manual | 50 State and Canada version: Oxygensensor, carbon canister (EVAP) system, Exhaust Gas Recirculation (EGR) system, EGR temperature sensor and engine RPM limiter |
| 004 | AG4 Automatic | 50 State and Canada version: Oxygensensor, carbon canister (EVAP) system, Exhaust Gas Recirculation (EGR) system, EGR temperature sensor and engine RPM limiter |
| 005 | 01K or 01F Automatic | 50 State and Canada version: Oxygensensor, carbon canister (EVAP) system, Exhaust Gas Recirculation (EGR) system, EGR temperature sensor and engine RPM limiter. |
| -- | -- | Variants other than those listed donot apply for US vehicles. |
ENGINE CONTROL MODULE, REMOVING, INSTALLING AND REPLACING
REPLACING
If replacing the (J192) ECM, perform the following steps in the sequence given.
Activate ECM version until ECM identification number is displayed.
Display will show the following:
Interpret code using code variants in the ECM CODE CHART , compare and note.
Press --> button.
Display will show the following:
Switch OFF ignition.
REMOVING
Refer to the appropriate service information.
INSTALLING
Refer to the appropriate service information.
IDLE SPEED AND CO CONTENT, CHECKING
ECM 8AO 906 266B has Oxygen control learning capability, which allows for the deletion of the CO potentiometer in the Mass Air Flow (MAF) sensor. As a result of this technical change, CO content can no longer be manually adjusted. For testing the mass air flow sensor several changes have resulted relative to the mass air flow sensor with CO potentiometer.
REQUIREMENTS
- Exhaust system must be leak-tight.
- Engine coolant temperature must be min. 85°C (185°F).
- Throttle must be in closed throttle position, if NO, adjust.
- All electrical consumers must be switched OFF
- A/C system must be switched OFF
- Do NOT have any pressure measuring devices connected.
- Place transmission selector lever in P or N position
- Ignition Switched on.
IDLE SPEED, CHECKING
Idle speed CANNOT be adjusted. Idle speed is checked during engine basic adjustment.
Read Diagnostic Trouble Code (DTC) memory using VAG 1551 scan tool.
Start engine and let idle.
Press 0 and 4 buttons to select function 04.
Display group 03 and observe value in channel 1.
- Must be 700-800 RPM.
If specific value is NOT obtained:
Read DTC memory again, see Repair Group 01 (Fuel & Ignition) for additional information.
If idle speed RPM is too high and there are no codes stored in DTC memory, perform the following checks:
Check closed throttle switch.
Check for excessive infiltrated air (leakage in).
Check Idle Air Control system check valve.
Check learn values for Idle Air Control system, see ENGINE BASIC ADJUSTMENT.
If idle speed RPM is too low and there are NO codes stored in DTC memory, perform the following checks:
Check closed throttle switch.
Check Idle Air Control system check valve.
CO-CONTENT, CHECKING
CO-content CANNOT be manually adjusted.
Connect VAG 1363 CO tester (or EPA approved equivalent) to the right side CO tap.
Check CO content.
- specified value: 0.3 to 1.2 Vol.%
Switch tester connection to left side CO tap and repeat CO check.
- specified value: 0.3 to 1.2 Vol.%
If CO-content is less than 0.3:
Check for air leaks around the CO tap or test adapter connected to the CO tester.
If CO-content exceeds 1.2:
Check for exhaust leaks between the engine and the Oxygen sensor.
If CO-content is approx. 1.7:
Check for faulty spark plug.
If specification is NOT obtained:
Activate DTC memory again. See Repair Group 01 (Fuel & Ignition).
If NO code stored in DTC memory:
Perform "reading measuring value block" using VAG 1551 Scan Tool to pull up measuring value block 4.
Observe value in channel 8 (Oxygen sensor). see Repair Group 01 (Fuel & Ignition) for additional information.
MASS AIR FLOW (MAF) SENSOR (G70), CHECKING
REQUIREMENT
- Fuse 27 OK (in fuse/relay panel).
VOLTAGE SUPPLY, CHECKING
Disconnect Mass Air Flow sensor harness connector.
Switch Fluke 83 multimeter to 20 Volt range.
Connect multimeter between terminals 2 and 3, using jumper wires from VW 1594 adapter kit. See Fig 13 .
Switch ON ignition.
- Must be between approx. 12 and 14 Volts.
If specified value is NOT attained:
Check that fuse 27 is OK
* in fuse/relay panel
Check wiring between terminal 3 and circuit breaker 1 for continuity.
- Must be max. 0.5 ohms.
Check wiring between terminal 2 and engine ground for continuity.
- Must be max. 0.5 ohms.
WIRING BETWEEN ENGINE CONTROL MODULE (ECM) AND MASS AIR FLOW (MAF) SENSOR, CHECKING
Disconnect ECM from ECM harness connector.
Connect VAG 1598 Test Box to ECM harness connector using adapter cable VAG 1598-11. See Repair Group 01 (Fuel & Ignition) for additional information.
- The ECM is left disconnected.
Check signal wire for continuity between terminal 1 of MAF sensor and terminal 42 of Test Box.
- Must be max. 1 ohms.
If the specified values are NOT obtained:
Eliminate open circuit or short between MAP sensor harness connector and connector A for the ECM. See Fig 14 .
| Mass Air Flow sensor harness connector terminal number | Engine Control Module harness connector terminal number |
|---|---|
| 1 | 2 |
| 2 | 5 |
MASS AIR FLOW (MAF) SENSOR FUNCTION, CHECKING
Pry protective rubber boot away from MAF sensor harness connector to expose terminals.
- Harness connector remains connected to MAF sensor.
Switch Fluke 83 multimeter to 20 Volt range.
Connect multimeter between terminals 1 and 2 using jumper wires from VW 1594 adapter kit.
Switch ON ignition.
- Must be approx. 0.3 to 1.1 Volts.
Start engine and let idle.
Switch OFF all electrical consumers.
- Radiator cooling fan must NOT be running.
Continuously vary RPM (by hand) between idle speed and 4000 RPM.
- Depending on RPM, voltage must change between max. 1.5 to 3.4 Volts.
If NO
Replace MAF sensor.
SPEED SIGNAL CHECKING
Disconnect ECM harness connector B and leave disconnected.
Connect VAG 1598 Test Box to ECM using adapter cable VAG 1598-11.
See Repair Group 01 (Fuel & Ignition) for additional information.
- The ECM is left disconnected.
Connect VAG 1527B LED tester between terminals 29 (signal) and 40 (plus) of Test Box.
Switch ON ignition.
- LED tester must light up at about half strength.
Lift front end of vehicle to allow wheels to be turned by hand.
Turn left front wheel.
- LED tester must become brighter (flashing).
If NO:
Check wiring for continuity between terminal 29 of Test Box and instrument cluster.
If NO:
Eliminate open circuit between terminal 9 of harness connector B and instrument cluster. See Fig 14 .
If wiring OK:
Continue troubleshooting using appropriate wiring diagrams and component location diagrams.
If LED tester lights up and flashes:
Switch OFF ignition.
Connect VAG 1598-11 adapter cable connector B to ECM connector B.
Connect LED tester to terminal 29 ( signal) and 40 (plus) of Test Box.
Switch ON ignition.
- LED tester must light up at half strength.
Turn left front wheel slowly by hand.
- LED tester must become brighter (flash).
If NO and if there were no stored Diagnostic Trouble Codes AND the ECM harness connector B was disconnected while performing the electrical checks
Replace (J 192) ECM.