DETROIT -- A decade ago, the typical automobile would have needed a trunkful of electronic equipment to operate as efficiently as it does today with a single 4-by-6-inch computer board.
On-board computers, as they are called in the industry, made it possible for auto makers to meet stringent federal emissions and fuel economy standards.
Operating as the 'brains' of anti-pollution devices and ignition systems, engineers say on-board electronic computers have made engine functions far more precise than any mechanical system could have.
In today's cars, computers help run the power train, which includes most working engine parts; vehicle control, including brakes and transmission; and in entertainment systems and diagnostics.
The hitch is, on-board computers must often be replaced instead of repaired. However, there are also sophisticated computer systems to diagnose a car's troubles, be they in the on-board computer or elsewhere.
Necessity was the mother of invention in development of on-Yqoard computers. Computer technology was being developed as early as the late 1960s at General Motors Corp., but there was no real incentive until the mid-1970s. The environmental movement and the energy crisis prompted federal agencies to set fuel economy and emissions standards for the nation's automakers.
'With the inception of emissions standards and improved fuel economy requirements, it became clear that we needed more precise control of engineer and carburetor processes,' said James Padilla, executive engineer in Ford Motor Co.'s electronics division.
Luckily for the auto makers, great strides were taking place in development of the computer chip that made it possible to condense a wealth of equipment and controls into a tiny unit.
'In 1970, it took a trunkful of electronics to do what you can put in your fist today,' said GM executive engineer Oliver T. McCarter. 'It was very bulky, expensive and impractical.'
The first on-board computer was offered in the Lincoln Versailles in 1978. Dubbed Electronic Engine Control or EEC-I, the computer needed two operating boards plus a host of components. It was basically an ignition control system.
Today's version, the EEC-IV, would fit in a jacket pocket. It monitors engine ignition, exhaust gas recirculation, air-fuel ratios, adjusts the engine for altitude and even cuts off the air conditioner pump under full throttle to allow greater horsepower to be sent to the wheels.
GM has a similar system called the GMP-IV.
Ford's system is installed on 85 percent of its cars -- all except the subcompact Escort -- and should be available on all cars and trucks by the late 1980s.
EEC-IV can perform more than a million calculations a second -- a task that would take a person using a hand-held calculator more than a year.
The in-dash computer has two parts -- the central processing unit, which sends out commands at a high speed, and memory chips dubbed M-ram. M-ram was likened by Padilla to personal computer software.
A major problem with the on-board computer is that it is installed already programmed, and cannot be inexpensively reprogrammed.
If an EEC-IV unit goes on the blink, it must be replaced at a cost of around $400. Auto makers hope eventually the units can be remanufactured instead of scrapped, bringing the cost down to $150 to $200.
Auto makers are working on methods to help service personnel diagnose problems in both the car and the computer system to avoid junking the on-board computers.
In many cases, mechanics who were trained for decades to handle mechanical problems now are being trained for computers.
It is a 'whale of a task' to inform dealers and mechanics, Padilla said. There are 50 different diagnostic codes in the EEC-IV system that mechanics must choose from to find the proper repair.
But McCarter said there is no alternative.
'We've either got to put a lot more (diagnostic) equipment in the hands of our dealers and mechanics or make it easier for them to tell what the problem is,' said the GM engineer. He predicted dealers would prefer the second option.
At some point, the engineers predicted on-board computers will include a feature Ford has dubbed 'Keep Alive Memory.'
KAM will enable mechanics to play back the unit's memory to diagnose occasional problems -- things that seem to disappear once a car is taken to the shop.