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

MERLINS RALLIART & EVOLUTION-X TUNING GUIDESECTION 10 – INJECTOR TUNING10.01-INJECTOR SETUP INTRODUCTIONThe stock injectors on the EvoX and RALLIART are low impedance DENSO unitsrated at 532cc/min. Generally speaking, the stock injectors will give you adequatefuel flow with a TBE, a better hot-side intercooler pipe, stock turbo and 20-22 lbs ofboost by redline.If you plan to use a 20G or larger turbo and or raise the boost level to 25 psi orhigher running gasoline, then it is advisable to get bigger injectors. In this caseinjectors in the 700 – 850 cc/min range will be required as suitable replacements.If you plan to use E85, then think 1050 cc/min as a starting minimum injector size.The assumption here being that other power modifications will be employed, like a20G or larger turbo and other breathing / plumbing modifications plus lots of boost.When you install bigger injectors, you will have to alter these parameters:SCALINGLATENCYSTART – PRIMER IPW v TEMPSTART - CRANKING IPW v TEMPThese tables must be altered in the ECU to suite the new injectors, otherwise theair fuel ratio settings will be way-out, your car will idle poorly and stall on occasion,run rich and generally behave poorly.So how do you go about scaling your new injectors?It has been said on the Evo forums that dialing-in new injectors is a pain in the arseand will require a lot of testing and logging. This may well prove to be the case ifthe injectors are not well documented and in common usage. However, the tunershave developed simple procedures to get just about anything “sensible” dialed-infairly quickly. But you will have to log the trims using EvoScan etc. By “sensible” Imean something less than 1200cc/min flow rate on gasoline.Above that and the ECU struggles or just cant cope as there is a minimum injectorpulse width parameter that sets a floor value of IPW of 1.28ms. Also, the ECU doesnot have peak-and-hold injector drivers. The Evo uses a saturated driver with aballast resistor in series with the injector. This setup will have higher latency timesthan a peak-and-hold injector driver system.As a side note, I have read of tunersadding an external interceptor injector driver box with peak-and-hold drivers. So,just about anything is possible.REV: 0.K merlin@three.com.au Page 84 of 134