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

MERLINS RALLIART & EVOLUTION-X TUNING GUIDE10.09-INJECTOR TUNING – START CRANKING IPW v TEMPFollowing on from the first primer shot of fuel is the cranking fuel enrichment. Thisseries of injector pulses is calculated from the 11 element START CRANKING IPW vTEMP table. The value is not fixed though, there is a percentage v time tableassociated with it that controls the decay rate of the pulse width. This is to preventthe engine from flooding under prolonged cranking. Once again, the need for thisparameter is due to poor cold fuel atomization. The table values are added to thelatency values, thus directly adding the table to the final cranking IPW. The tableonly applies when the engine is in START MODE ie below 438 rpm.Figure 65:INJECTOR TUNING – START CRANKING IPW v TEMP, Evo9There are two cases where this parameter will need to be tuned for your specificapplication:3. When the injectors have been replaced with larger flow capacity types.4. When using alcohol E85 fuel 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 - CRANKING IPW = old IPW x [old injector scale / new injector scale]When using E85 alcohol blend fuel, multiply the new table values as follows:-32*C to +7*C+20*C+34*C+50*C+77*C+82*C= x*1.30= x*1.25= x*1.20= x*1.00= x*0.9= x*0.8In practice with E85, the requirement for extra fuel is exacerbated when the engineis stone cold, not so much when warmed-up to operating temperatures. Note thatthe IPW during START MODE also has the LATENCY time in mS added to it.REV: 0.K merlin@three.com.au Page 97 of 134