Merlins Ralliart and EvoX TUNING GUIDE Version K.pdf - EvoScan

MERLINS RALLIART & EVOLUTION-X TUNING GUIDESECTION 9 – BOOST TUNING9.01-BOOST TUNING INTRODUCTIONThe boost control maps and tables for the RALLIART and the EXOX can be gearselected. In other words, the ECU will select which maps to use based on the gearcurrently in use. There is a single parameter which defines the rpm/mph and thisparameter can be tweaked to flip the maps. However, Mitsubishi have elected toutilize this feature on the SST equipped vehicles only. So the maps and tables aregenerally set the same on manual gearbox vehicles.You can utilize this feature though as the coding is fully active and working.Another change from what we have had with earlier Evos (JDM excepted) is the useof two boost control solenoids on the EvoX – the RALLIART still only has one boostcontrol solenoid. When you look at the tune using EcuFLASH, the waste-gate dutycycle tables labeled REACTIVE are the main tables (present in both EVOX andRALLIART) while the tables labeled PASSIVE are for the second BCS in the EVOXonly. A RALLIART ROM XML may have these PASSIVE tables listed, they just don’tdo anything.The PASSIVE BCS has not error correction code associated with it, so it just doeswhat the table specifies.The REACTIVE BCS has boost error correction coding that adjusts the wastegateduty cycle to try and get the engine load to match the target load.To really get on top of boost tuning requires some method logging the boost withload and rpm so it is clear which map cells need to be modified. The data loggertakes the signal and based on the sensor calibration data translates the voltage intopsi. The EvoX is equipped with a 3 bar MAP sensor that sits atop of the inletmanifold, so now you can log the boost directly from the ECU provided you haveproperly modified your EvoScan xml file to log boost.Now for the bad news. The stock boost control solenoid, in combination with thestock restriction pill will only allow a little further increase in boost and airflow.The first fix is to replace the stock pill with one having a smaller feed hole. A pillwith a 0.8mm hole will get the system back into reasonable adjustment range.The second fix is to replace the stock 2-port BCS with a 3-port BCS. This method isby far the best setup and does not require any changes to the stock pill. Bothmethods allows full use of the ECU boost control features including twin boosttables.REV: 0.K merlin@three.com.au Page 73 of 134