General

MPI System Inputs And Outputs:

OPERATION
The MPI electronic control unit (ECM) processes input signals, filters out stray signals and sends the results to the operating components of the fuel injection and ignition systems.
The ECM also provides for self-diagnosis of the MPI system. The MPI system is adaptive or self-learning. The ECM learns continuously by using a sophisticated feedback system to constantly readjust the various basic control settings. These values are then stored in its electronic memory.
The adaptive capability allows the ECM to compensate for changes in the engine's operating conditions, such as altitude changes, intake leaks or other deviations.
If the vehicle battery or MPI ECM is disconnected, the vehicle must be driven for a few minutes so the MPI unit can "re-learn" its operating conditions.

NOTE:
Early in 1993 production, vehicles have been fitted with a new Engine Control Module (ECM) as a "running change in production". Vehicles equipped with the new ECM will also have a new Mass Air Flow Sensor (without CO Potentiometer) and new Heated Oxygen Sensors. The new control system can be identified as follows:

^ The New Engine Control Module (ECM) has Part No. 8A0 906 266B

^ The Old Engine Control Module (ECM) has Part No:
4A0 906 266A
4A0 906 266AA
4A0 906 266AB
8A0 906 266A

^ The New Mass Air Flow Sensor (MAF) has a 3-wire harness connector

^ The Old Mass Air Flow Sensor (MAF) has a 4-wire harness connector

If your vehicle has the Old ECM and control system, use information for a 1992 model vehicle as some procedures and specifications are different. This will ensure maximum driveablity performance from your vehicle.

CAUTION!
Do not install the New ECM into vehicles with the Old control systems and vice versa.