The discussion around Electronic Control Units (ECUs) in Diamond Star Motors (DSM) cars, specifically models like the Mitsubishi Eclipse, Plymouth Laser, and Eagle Talon, often brings up questions about compatibility and performance differences between automatic and manual transmissions. One common point of interest is whether you can use a manual ECU in an automatic DSM car and what the implications are, particularly concerning fuel delivery.
The original forum discussion highlights a crucial aspect: the resistor packs and injector sizes differ between automatic and manual 1G DSMs. This difference isn’t arbitrary; it’s directly linked to how the engine management system delivers fuel. In essence, the resistor pack is tailored to the specific injectors used in each transmission type. The post suggests that swapping resistor packs could be a method to adjust air-fuel ratios when upgrading to larger injectors, a practice familiar in performance tuning communities.
However, another perspective from a well-regarded source, Thomas Dorris of DSMLink, sheds further light on the ECU differences. According to Dorris, the primary distinction between stock automatic and manual ECUs lies in the injector size and the assumed fuel pressure. This isn’t just a minor detail. The information suggests that a stock manual ECU, when used in an automatic car setup without other modifications, could lead to the engine running approximately 6% leaner than intended.
This 6% lean condition is significant. Running lean means the engine receives less fuel relative to air, which can increase combustion temperatures and potentially lead to engine damage over time, especially under demanding conditions. While the engine might “run” as the initial forum post mentions, it’s crucial to understand that “running” and running optimally (or safely) are two different things.
Therefore, while it might be technically possible to install a manual ECU in an automatic DSM car, it’s not a straightforward plug-and-play solution for optimal performance or engine longevity. The difference in injector sizing and fuel trims necessitates careful consideration. If you’re contemplating this swap, understanding the potential for a lean condition is paramount. Solutions to mitigate this lean condition could involve adjusting fuel pressure, utilizing aftermarket fuel management systems like DSMLink to fine-tune fuel delivery, or indeed, as initially suggested, considering the resistor pack in conjunction with injector choices. Always prioritize accurate air-fuel ratios for a healthy and performing DSM engine.
