What really got the ball rolling for on-board computer controls was pressure by the federal government for cleaner-running and more fuel-efficient vehicles. “On-board computer controls and emerging chip technology gave the truck manufacturers the ability to meet new government standards,” Heffington said. “There was just one problem..
The problem was that the manufacturers needed to build trucks that appealed to a wide and diverse market. Left out of the equation were those owners who needed their vehicles to serve special purposes—such as outdoorsmen who tow boats, haul heavy loads, or drive through deep troughs of mud. That opened the door to the aftermarket to supply chips that could customize a vehicle’s performance to an individual’s needs.
When computer-controlled engine management systems first came on the scene, chips—called Programmable Read Only Memory chips, or PROMs—could be unplugged and replaced, much like you’d change fuses in an electrical circuit.These devices contained ignition spark and fuel delivery information (calibrations) that could increase vehicle performance while still meeting more stringent emissions standards.
During this period, aftermarket chip manufacturers designed and built PROMs that could be dropped in, in place of the original equipment manufacturer (OEM) PROMs. But over time OEM on-board computers evolved into what you see today: electronically erasable PROMs.
The advantage is that “these programs control an ever increasing number of engine and powertrain functions in an increasingly sophisticated way. These functions include ak-fuel ratio, spark curves, transmission shift and lockup points, cooling fans, and even certain suspension controls. All of these capabilities can be tuned to fit the particular needs of a particular truck.” Hefflngton said.
The disadvantage is that these sophisticated functions required another huge technological leap by the aftermarket suppliers, and chip installation now means downloading codes via a cable attached to the vehicle’s computer.