Why would I want to change my car or truck’s engine computer? The best way to get better gas mileage out of your vehicle is to increase the engine efficiency. The most cost effective way to do that for most vehicles is a high performance exhaust and cold air intake installation. As a bonus you’ll also get more power. That’s why these two modifications are the most popular and usually the first things done to increase an engine’s performance.
The next modification on the list would be a change to the engines electronic control unit (ECU) calibration. This is done to maximize the gains provided by increasing the flow from the intake and exhaust. Changing the ECU calibration also accounts for the fact that most performance exhaust systems and cold air intakes are tuned to work best in a higher RPM range than the stock parts.
Depending on your specific engine type’s ECU, you can do that by one of 4 different methods:
1) Changing the chip that stores the calibration, called the PROM or EPROM chip
2) Reprogramming, or “Flashing” the stock EPROM chip.
3) Installing what’s known as a “piggyback” computer or ECU. That is an auxiliary unit that plugs into the stock wiring and alters the programming of the stock unit. They can plug into the OBD-II port under the dash, or between the existing computer and the car’s wiring harness.
4) Changing the computer for a different one entirely.
With some vehicles you have a choice of more than one of these methods, depending upon your specific tuning needs and the manufacturer of the equipment you’re using to make the upgrade.
The ECU controls every aspect of your vehicle, so modifications here offer a huge potential for improvement. The ECU commands the fuel mixture at different load and rpm ranges, the rev limiter, turbo boost, ignition timing maps, transmission shifting in automatic transmission vehicles, and even the variable valve timing / lift in some engines. As you can imagine, being able to change these parameters can really increase your car or truck’s performance, weather you’re trying to maximize gas mileage, power or possibly both, depending upon how you’re using the vehicle.
Some computers even let you change programs on the fly, so you can have the best of both worlds. For long trips, you can maximize highway fuel economy, while in town you can get increased power and drivability. For autocross, drifting, drag racing, and other track events you can choose yet another ECU setting.
25 years ago, in the dark days of the 1980’s, many people thought performance cars would be gone for good. Little did they realize automotive performance would enter a brave new age, when performance and fuel economy could coexist in the same vehicle.
Chips and programmers are made by a few companies. Three of the leaders are Hypertech, Jet, and Superchips. Online retailers such as AutoAnything usually have some type of special offers on programmers and chips. Check on the latest programmer specials here.
All three of these companies have well deserved reputations for engineering and building very effective devices to get your vehicle the performance you need. With the recent increases in fuel prices they’ve introduced programmers that are targeted toward maximizing gas mileage, rather than pure horsepower. If fuel prices stay over $4.00 per gallon, they will continue to be very strong sellers. If gas prices rise to $5.00 they won’t be able to keep them in stock.
