The Achilles heel of Chrysler EFI performance has always been the calibration. Anyone who has delved into this sport beyond a cold air kit and exhaust system has stubbed his toe on the calibration issue. It started back when the first EFI-equipped engines were modified, and is even a bigger complication today because of OBD-II. Different approaches have been tried that range from hacking proprietary OE computer code to the integration of a stand-alone aftermarket ECU. All of these technologies have raised the bar and allowed power, along with drivability, to ratchet up a notch, but it is still not the answer. The complete system integration of other vehicle functions into the engine management system does not allow the removal of the factory ECU and, thus, has created an obstacle to having both horsepower and drivability, along with emissions compliance.

Finally, after nearly twenty years of failed attempts by the industry to cure the Mopar calibration blues, an ingenious product has been brought to market by Ida Automotive-the EMC Tuner.

The EMC Tuner is an ancillary computer wired in between the engine's sensors and the Mopar engine management system. An over-simplification of its function would be that it intercepts the sensor outputs and changes them to impact the fuel and timing commands to suit the needs of the particular engine, in line with the values inputted by the tuner. It must be understood that the EMC Tuner modifies the signals only and still needs the factory ECU to perform the work of pulsing the injectors and controlling the ignition timing.

The Better Mousetrap
The problem with the Mopar ECU has not been its quality or capabilities, but the lack of access to make the required changes to get the most power from a stock or modified engine. Whenever the power output is increased, the fuel and spark curve need to be reworked. Altered camshaft profiles or increased airflow through cylinder head modifications change not only the horsepower and torque, but at what rpm they occur. Forced induction and nitrous bring along their own set of issues and need accurate tuning to pay dividends while preserving the integrity of the engine. every engine has a slightly different tuning characteristic than its identical twin. This often leaves some horsepower and drivability on the table, even on a completely stock vehicle as our subject '01 Durango. The Durango utilizes the same components as the Dakota, so the process is the same.

ACCEL/DFI, Speed-Pro, Electromotive, and the Holley Commander 950 are considered stand-alone EFI controllers. They replace the OE engine management system, boasting tuning ease with application-specific software. But this eradicates the factory ECU and its important controls. The integration of functions is key to a successful OE calibration logic, creating a synergy between ancillaries of the vehicle and engine. Charcoal canister purge, torque converter clutch, EGR, cruise control, air conditioning, and air injection reaction are all essentials of a modern management system. All of these functions need to be kept operational for the vehicle to be considered emissions-compliant. It is true that stand-alone ECUs have been integrated into homemade piggyback systems with success. Often, this results in a complex array of electronics and the installation of an additional wiring harness for the guest ECU. In addition, OBD-II parameters cannot usually be met by the aftermarket ECU and perpetually flag codes and "service engine soon" lights.

In contrast, the EMC Tuner, which is housed in a small plastic enclosure, has its own software and wiring harness and disrupts none of the factory controls. It can be used to alter 256 different set points in either the fuel or timing map. If no value is inputted into the EMC Tuner at a given load or rpm, that cell automatically reverts back to the OE program. In addition, the EMC Tuner has the ability to work with all Chrysler MAF and speed density systems along with any type of ignition.