What does my vehicles computer do

What does my vehicles computer do?

You won't find a monitor, keyboard or the latest version of Windows under your hood, but your car actually does have a sort of on-board computer. It's a small box, actually called an Electronic Control Module. It works with your car's sensors and control devices to keep your engine's operation at maximum efficiency. It's normally located under the dash, on the fender wall or on the fire wall.

What Does It Do?

The EMC is the heart of a complex system of sensors and actuators through-out your engine and exhaust system. You might want to think of the car's sensor as its nerves, the car's pumps, valves, distributor and other actuators as its fingers and the ECM as the brain that connects them. The sensors send a message to the brain that something isn't right - not enough air in the air/fuel mixture, for instance. The brain then tells it's fingers - the mixture control solenoid, fuel injectors and others - to change their operation until the mixture entering the cylinders is correct.

The ECM also "remembers" what the sensors tell it. It notes problems and stores them as trouble codes in its memory. It converts these trouble codes into warning signals like your "service engine soon" light, and saves information about the problem that can be retrieved later by a qualified technician.

What Do My Car's Sensors Tell The Computer?

The sensors in today's cars provide the ECM with an amazing variety of information, all of which is used by the computer to maximize engine operating efficiency and minimize emissions. Here are some of the most common ones:

Air Temperature Sensor
Reports changes in the air density that alert the ECM to change the car's air/fuel mixture ratio - helps to improve cold engine performance

Mass Airflow Sensor
Measures the amount of air being drawn into the engine so the computer can compensate for changes in outside altitude and temperature.: Camshaft Position Sensor
Monitors the rotation of the engine so that the computer knows precisely when to trigger ignition spark or the fuel injectors.
: Coolant Temperature Sensor
Reports temperature in the cooling system so the ECM can adjust fuel delivery and timing for optimum performance.: Crankshaft Position Sensor
Provides the computer with RPM information that's used to calculate injector repetition, timing advance and distributor less ignition synchronization.: Detonation Sensor
Detects engine knock or "ping" instantly so the computer knows to retard spark timing, which reduces overheating and excess emissions.: MAP Sensor
Measures engine vacuum and tells the computer how much load the engine is under so the computer knows how to adjust fuel delivery and timing. MAP stands for Manifold Absolute Pressure.: Oxygen Sensor
Sniffs out the amount of oxygen in the exhaust. The computer uses this data to keep the engine's air/fuel mixture at a proper 14.7:1 ratio.: Throttle Position Sensor
Reads the throttle's angle and speed of movement so that the computer can match fuel delivery to the volume of air and ignition timing to the load.

How Much Of My Car Does The Computer Control?

The ECM pretty much runs all of your car's fuel delivery, spark timing and emission systems, among other functions. Its job is to keep your car running as efficiently as possible for as long as possible and it does this by constantly compensating among many of the engine's components for best results. Some of them are:

Fuel Injectors

The ECM tells the fuel injectors exactly when and how much fuel to inject.

Idle Air Control

Used by the ECM to increase or decrease idle speed.

Idle Speed Control

Set by the computer, it takes over every time you lift your foot off the accelerator.

EGR Valve

Under control of the ECM, recirculates a precisely measured amount of exhaust back into the engine, which lowers combustion chamber temperature and recudes emissions.

Fuel Pump Relay

Runs the fuel pump which sends fuel to the injectors or carburetor, according to instructions from the ECM.

Mixture Control Solenoid

Used on computer controlled carburetors it blends air and fuel to produce needed power with minimum emissions.

Idle Speed Control Actuator

Adjusts idle speed as dictated by the computer to keep the idle steady.

Ported Vacuum Switch

Opens and closes vacuum lines, under computer direction, to various emissions components.

Can I Fix A Computer Related Problem Myself?

Unfortunately, no. The complex relationship between the sensors, computers and acturators, plus the advanced electronics required to operate them, make do-it-yourself repairs all but impossible. Even a trained technician needs special diagnostic equipment to tap in and read the signals that travel between system components, and to retrieve trouble codes stored in the computer.

You can however, help minimize or eliminate computer related problems by making sure your car receives a completed professional diagnostic check and tune up at the interval recommended in your owners manual.

If The Car Needs New Parts What Kind Will It Need?

We will install parts that meet or exceed the specifications that your car's manufacturer has established. Many high quality replacement parts actually work better than the original part that came with the vehicle, because they include improvements to correct flaws of deficiencies which were built into the original part by the car maker.

Remember to get your vehicle in for diagnosis as soon as you have a warning light come on. This may prevent any further damage to the vehicle and perhaps the extra cost of repair due to sub sequential damage from lack of attention.