Car Corner: Complexities of modern car computers
It’s amazing to think that a computer controls many aspects of our modern day cars. When you consider all of the problems we tend to have with our home computers, you begin to wonder how the computers in our cars can keep them running safely and efficiently — but actually they do a very good job of it. When we get in our cars and drive off, most of us don’t even think about what’s going on under the dash or hood. In reality, the computer and related components are controlling all engine, transmission and braking functions, in addition to possibly the lighting, heating/air conditioning, seating and steering positions and audio. In some cases, the computer along with radar sensors can even slow the vehicle when approaching another car when the cruise control is on or when there is an eminent collision ahead.
The auto computer or engine control unit (ECU), as it is called, is a unit that controls a series of actuators on an internal combustion engine to ensure the optimum performance. It does this by reading values from a multitude of sensors within the engine bay, interpreting the data using multidimensional performance maps and adjusting the engine actuators accordingly. A good example of this is when you use the wrong octane level gasoline in your car, which may result in an engine “knocking” noise. If the ECU detects knock, it will delay or retard the spark to eliminate the noise.
Before ECUs, air/fuel mixture, ignition timing and idle speed were mechanically set and dynamically controlled by mechanical and pneumatic means. One of the earliest attempts to use a unitized and automated device to manage multiple engine control functions simultaneously was the “Kommandogerat” created by BMW in 1939, for the 14 cylinder aviation engine. This device replaced 6 controls used to initiate hard acceleration with one control in the aircraft. However, it had some problems as it would surge the engine, making close formation flying somewhat difficult and it switched supercharger gears harshly and at random, which could throw the aircraft into an extremely dangerous stall or spin.
Hybrid digital/analog ECU designs were popular in the mid 1980s. They used analog techniques to measure and process input parameters from the engine, then used a look-up table stored in a digital ROM chip to yield precomputed output values. The ROM type of system is amenable to engine tuning if one knows the system well. The disadvantage of such systems is that the precomputed values are only optimal for a new engine. As the engine wears, this system is less able to compensate than a more modern ECU system.
Modern ECUs use a microprocessor which can process inputs from the engine in real time. The ECU contains the hardware and software necessary for the system. The hardware consists of electronic components on a printed circuit board. The main component on the circuit board is a microcontroller chip. The software is stored in the microcontroller so the unit can be pre-programmed by uploading updated code or replacing chips.
Some modern car enthusiasts use devices know as “tuners” to change many of the vehicle’s computer settings for more horsepower which usually requires the use of premium gas. Both my 2006 Dodge Charger and 2007 Mustang have been retuned for a higher level of performance.
So the next time you get behind the wheel of your auto, think about all of the things that are happening within the vehicle’s components you don’t see, or even care about, but ensure the best and most efficient operation of your vehicle.
Upcoming events
♦ Today: All American Muscle Night cruise-in at 6 p.m. at Arby’s on U.S. 19 in Crystal River
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Ken McNally is a car enthusiast from Citrus County and his Car Corner columns appear twice each month in the Hernando Today. Email him at [email protected] or call (352) 341-1165.
