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

MERLINS RALLIART & EVOLUTION-X TUNING GUIDE10.08-INJECTOR TUNING – START PRIMER IPW v TEMPA 4-cycle gasoline engine will require extra fuel when starting, particularly whencold. This is due to the poor atomization characteristics of cold fuel with a cold inletmanifold and head. The requirement for extra fuel diminishes as the enginetemperature approaches full operating temperature. There are two tables providingfor fuel enrichment when starting the engine.The 9 element START PRIMER IPW v TEMP table function is to help prime theengine, by providing a single large initial fuel pulse to wet the inlet manifold. Thetable values are added to the latency values, thus directly adding the table to theIPW. The table only applies when the engine is cranking and only a single pulse isapplied from this table. Following this first pulse are the CRANKING enrichmentpulses.Figure 64:INJECTOR TUNING – START PRIMER IPW v TEMP, Evo9There are two cases where this parameter will need to be tuned for your specificapplication:1. When the injectors have been replaced with larger flow capacity types.2. When using alcohol fuel (E85) with bigger injectors.With case one, where the injector size has been increased, the values will need tobe reduced by the percentage difference between the old and new sizes. This isdone to prevent flooding and/or plug fouling on start-up. So the IPW values willneed to be altered based on the new injector scaling. Use the following formula toarrive at some initial values:New START - PRIMER IPW = old IPW x [old injector scale / new injector scale]When using E85 fuel, then the values from 34°C through to 82°C should to beprogressively reduced down to about 1mS at 82*C.REV: 0.K merlin@three.com.au Page 96 of 134