Modular Engine Management System
| Manufacturer | Rover Group / Motorola |
|---|---|
| Type | Electronic automobile engine management |
| Release date | 1989 |
The Modular Engine Management System, or MEMS, is an electronic control system used on engines in passenger cars built by Rover Group in the 1990s. As its name implies, it was adaptable for a variety of engine management demands, including electronically controlled carburetion as well as single- and multi-point fuel injection (both with and without electronic ignition control.) When fitted to carbureted engines, the system is referred to as "ERIC", which stands for "Electronically Regulated Ignition and Carburetion". The abbreviations "SPi" and "MPi" refer to the single-point and multi-point injection configurations, respectively.
MEMS was developed as a joint venture between Rover and Motorola in 1989, and it was first fitted to the Austin Montego 2.0L. Over the next seven years, the system appeared on cars across Rover's model lineup, including the Mk VI and Mk VII Mini and the MG F / MG TF.
Like other electronic engine management systems, MEMS reads data from a number of sensors and computes an appropriate fueling rate and ignition advance/retard. The ECU samples engine speed, manifold absolute pressure, coolant temperature, intake air temperature, throttle position, and battery voltage. Base values for the fueling and ignition timing are each retrieved from a three-dimensional map, and certain sensor values are applied as correction factors, for example, to enrich fueling during wide-throttle acceleration or on cold startup. The MEMS firmware also features a limp-home capability (referred to in the literature as "limited operating strategy") that will substitute a nominal value for any non-operative sensor.
When the system detects a fault, a corresponding fault code in stored in the ECU's nonvolatile memory. Fault codes may only be cleared by commanding the ECU via the diagnostic port.
Several different revisions of MEMS were produced:
- 1.2: First version to enter production. Not designed for use in vehicles with catalytic converters. ECU has single 36-pin connector.
- 1.3: Designed with capability to control emissions-related equipment. ECU has two connectors (one 36-pin and one 18-pin).
- 1.8: Introduced in mid-1994, version 1.8 of the system uses a redesigned mechanism for idle air control.
Diagnostics
Because it was designed before industry-wide on-board diagnostics were standardized, MEMS uses a proprietary diagnostics protocol and signaling scheme. On earlier cars, the diagnostic port used a circular three-pin connector (type 172202 manufactured by TE Connectivity), where later cars switched to the standardized 16-pin ISO J1962 connector type.