Topic: How do computers control engine operations?

Computer Control Systems

The term Closed Loop represents a system that can modify air-fuel ratios and then monitor the results of combustion in the exhaust system. The computer control system will then readjust the air-fuel ratio based on the data it receives from the exhaust gas sensor and other engine and vehicle input sensors. Input sensors send either voltage signals, frequency signals, or digital signals to the engine control computer. The computer can activate output devices, by either supplying a ground path for the circuit or by supplying power for the circuit. The ECM converts analog voltage signals or frequency signals into digital (on\off ) signals. These digital signals are then converted into binary code and stored in a memory chip called Random Access Memory or RAM.

ECM Operation

In order for a computer to operate it must have some preset instructions. When power is supplied to the ECM it reads a set of instructions that have been placed in a memory chip similar to the BIOS (basic input / output system) program in a PC. The instructions allow the computer to turn on and start monitoring input signals. This program restricts the computer's ability to control engine operations until the engine reaches operating temperatures and a certain time period has passed. This program is stored in a memory chip called Read Only Memory or ROM. A second set of instructions is also necessary for the correct operation of the computer. This set includes information about the vehicle such as engine size, transmission type, vehicle weight, rear axle ratio, tire size and installed accessories. This data is used by the ECM to establish correct timing advance curves and air- fuel ratios. The information is stored in a memory chip called Programmable Read Only Memory or PROM.

ECM Profiles & Coverage

We offer quality remanufactured products and knowledgeable professionals ready to assist with any questions you might have. Coverage from 1979 to current module year. 100% Computerized Testing for all modules and Sensors using advanced test equipment. Latest OEM calibrations installed in all programmable modules. Common component failures are 100% replaced. Complete board reflow to ensure reliable performance. Upgraded components used to improve circuit reliability and performance. Expert technical support available with every product sold. Trilingual installation instructions.

BWD Automotive has over 15,000 computer profiles stored in our data banks, and when we rebuild an ECM we can reprogram it with the same data that OE used.