So far Project EVO has been an amazing project. For very little money we have gotten great results in performance gains into an already very good package. Our current goal is to max out the simple and relatively inexpensive mods while retaining the stock turbo, injectors, intercooler, and underhood piping before digging more extensively into Project EVO's systems to extract really big, yet streetable power gains.
Adaptive TuningAs most of you know, California is plagued with really bad 91-octane gas. Our gas really hates turbocharged cars. Due to what is a suspected juggling of the Motor and Research octane ratings California gas is more prone to detonation than its 91 octane suggests. Before those of you in the rest of the country where gas of up to 94 octane is available smugly chuckle, don't laugh too hard. With shortages and rising prices there is a call to standardize the many different regional gas blends into just a few. There is a good chance that more of you will fall under the doom of 91 octane as well. In that case, our experimentations of how to get power in a poor fuel environment should pique your interest.
One of the issues we have had with Project EVO from the beginning is inconsistency in measured and felt power and torque levels. Once we installed Vishnu's XEDE/Flash system and tuned it the inconsistency decreased greatly on the dyno but when driving on the street Project EVO still has variability issues. Sometimes it feels as if torque varys from 20-30 lb-ft depending on the fuel of the day, air temperature, and if the car had been cruising on the freeway or heat soaking in traffic.
This was due to the EVO's very active ECU, which was constantly cutting ignition timing and boost levels to ward off detonation. We resigned ourselves that this was what we had to accept with our fuel and the engineering of the stock systems in the car. That resignation didn't last long after we got a call from Shiv Pathak of Vishnu Tuning. Shiv was excited about the results he was getting with his new S.M.A.R.T. (Self Monitoring Active Real-time Tuning) upgrade for the XEDE system. The S.M.A.R.T. system converts the XEDE into a fully adaptive engine control system that is more sensitive, faster, and has a wider range of control authority than the stock system. The S.M.A.R.T. system is capable of making real-time adjustments to fuel, ignition timing, and boost in response to changes in driving conditions.
The S.M.A.R.T. system works well because it's faster to affect changes to the engine's control parameters and more sensitive than the stock ECU. This means it can detect and react to the onset of detonation before the stock ECU. It can also return the engine to normal non-knock conditions before the cylinders substantially heat soak. The factory ECU's signal processing is hampered because it resides within the noisy electrical environment of the ECU in intimate proximity to components like the power transistors that drive the injectors and ground the coil triggers.
This electrical noise can mask the telltale signature of knock. To combat this poor signal-to-noise ratio, the engineers at Mitsubishi make the knock response of the ECU conservative. The ignition is retarded a lot, boost pressure is reduced, and the fuel mixture is richened for quite a while before the ECU releases the clamp. The power and torque dip and the driver gets bummed out.