Learn How to Dump Your Car's ECU ROM

Join any car enthusiast group and you'll immediately see gearheads lamenting the "fact" that you can no longer modify cars. Those folks are nostalgic for the days when you could achieve serious power gains by re-jetting carbs or swapping a supercharger pulley. There is merit to their argument, because it is difficult to make modifications to modern cars without confusing their computers. Today's manufacturers tune their car's computers from the factory to be as efficient as possible. But you can adjust that tuning and sometimes you'll even gain some power when you do so. If that interests you, you'll first want to read P1kachu's guide on how to dump your car's ECU ROM.

Almost every system in a modern car has a computerized controller, but the most important is the ECU (Engine Control Unit). Digital ECUs date back the '70s and have been ubiquitous for decades now. Your car's ECU handles multiple functions, but most tuners are concerned with how it relates to power. The ECU utilizes a closed feedback loop so it can adjust fuel and air delivery in response to several parameters, such as the exhaust gases and engine RPM. In some cases, you can gain power (at the sacrifice of efficiency) by retuning how the ECU responds to parameters. You also may need to retune the ECU after making a modification, like after installing a new exhaust system.

The ECU's programming is stored in an EPROM (Erasable Programmable Read-Only Memory) chip. Modern cars use these reprogrammable chips, but older cars had read-only chips. In P1kachu's guide, he explains how he dumped the ROM from a 1995 Honda Integra (badged as an Acura in the US) and a 1993 Honda Civic. Both cars have their original ECUs, but with tuned firmware. P1kachu knew the origin of the Integra's tune, but not the Civic's. "Dumping" those, which means copying or backing-up the ROM contents, gave him a reference point for future tunes. The method for reading the ROM varies depending on the exact chip, but in this case, P1kachu was able to use an Arduino Mega, a breadboard, and a compatible socket.

If you have the same chip as P1kachu, you can follow his guide exactly and take advantage of the code he supplies. But even if you have a different chip, his write-up should serve as a jumping-off point for dumping your ROM. In most cases, you can also flash a new ROM to start your next tune.