A new style of Domination – An inside look at Holley’s Dominator EFI system

Written by Liz Miles
Photos courtesy of the manufacturers
The truth is that a well-tuned carburetor will produce the same peak horsepower as a well-tuned fuel injection setup. That’s great, but there’s so much more to a race car and even more to a daily driver than wide-open throttle. A street car often needs to cold start and drive at sub-zero temperatures while compensating for changing air and fuel conditions that a carburetor just can’t. Race cars require fine attention to detail when you’re dealing with multi-stage nitrous, a turbo, a supercharger, water/methanol injection, a transbrake, shift controls, and any other performance or consistency modification. Each of these can be electronically controlled and the fuel injection compensated for through Holley’s Dominator EFI.
The generations who were brought up through video games, typed-only homework assignments, and smart phones are going to latch onto the EFI wagon naturally while the traditionalists are going to need some convincing. In today’s racing world there’s no room for avoiding technology and Holley has created an EFI system for both the tech savvy, and the computer curious.The Dominator EFI is the top piece of a three-tier cake of EFI systems. It does require the tuner grasps the concept of EFI and its numerous adjustments. At the same time, Holley’s in-depth instructions guide you to the 10-percent of those adjustments that will have the most influence on your tune. Here we will go over the Dominator EFI’s features and what sets it apart from the others.



Dominator EFI components are sold a la carte since the available options are so vast, putting them into kit form wouldn’t make sense. Holley provides a step-by-step guide to make sure you piece together the right components. Once you’ve got everything, the physical installation is very simple and shouldn’t take more than a couple hours. This photo shows some of the options available with Dominator EFI, but not all of these components need to be installed on every vehicle. 


If you’ve got questions about any of the fields in any screen, simply drag-and-drop the Help (?) icon onto the topic in question and the explanation will pop up and clear up any confusion. The Help dropdown next to it gives you access to everything.



Basic Calibration Setup

This will be the first screen you work on after you select a base map from Holley’s stash that is closest to your combination. These are the most basic fields, but some of the most important as the system uses this information for its other functions. One subject in particular that shouldn’t be guessed about is the fuel injector and fuel pressure values. The duration that the injectors are open is calculated on these values and if they aren’t accurate, you will be chasing the tune into abnormal zones. There will be a couple other screens below the engine parameters selection pertaining to ignition and sensor types.



The engine will start and run off of the base calibrations previously selected. Learning is when the computer accounts for the difference between the base calibration and your particular engine. In the beginning, you will assign the learn gain at 100% until you feel confident that the engine has gone through a good number of rpm and load combinations. Once the engine had been operated long enough and in all conditions, you will want to disable or slow down the learn. Of course, you can manipulate this tune manually as you wish.



 Closed Loop

Closed loop is when the engine compensates based on feedback from the wideband oxygen sensors. Some aftermarket EFI systems operate in open loop where a base map is always used and there are no compensations for air or fuel changes. This can especially be a problem when you’re racing at different altitudes or if the weather changes through the night at the drag strip. The air isn’t the same at 2pm as 10pm, and re-tuning the car every pass doesn’t make sense. In the Closed Loop Parameters menu are adjustments that limit the percent change away from the base map specs. Closed loop can be beneficial as it can help save an engine in the event that a fuel pump or other component starts to fail. This screenshot shows a closed loop compensation percent limit of 20% meaning the ECU can’t adjust past 20% higher or lower fuel delivery in reference to your base map.



 Startup Tuning

If you’ve got a carbureted racecar, chances are there’s not going to be a choke. You’re inevitably going to be doing the cold-start dance of just the right number of pumps before turning the motor over and careful monitoring of pedal and RPM until it can stay alive on its own. The wonderful thing about fuel injection is that it can have a different tune for every occasion whether it be a cold start, or a hot lap. The Startup Enrichment section of the fuel modifications contains your cranking fuel, after-start hold off, after-start enrichment, and after start decay rate adjustments. These four charts allow you to change everything about how your car starts and runs at any temperature. Some of us have never been able to turn the key through the window and have it start and run on its own.



 Idle Functions

Holley did a lot to simplify setting up the idle routines with several basic dropdown selections chosen depending on the application. All of the idle adjustments are found by clicking icon that looks like a tachometer at the top of the screen. Here are the adjustments needed to maintain a healthy idle. Changes to this section will determine the method of which the computer changes the idle fuel map, spark timing, and IAC operation composition.



Acceleration Enrichment

This is the accelerator pump and discharge nozzle section of the tune. Acceleration Enrichment (AE) vs. Throttle Position Sensor (TPS) Rate of Change is the primary tool for this function. The enrichment is measured in pounds per hour added to the base map based on the TPS rate of change. Other adjustments include AE vs. MAP kPa % of change, AE TPS vs. Coolant Temp, MAP AE Time vs. Coolant Temp, AE Correction vs. TPS, and MAP AE vs. Coolant Temp. Together these adjustments allow for accommodations for any engine load, at any temperature, with any air, at any time!


Base Mapping (images: screen shot and section graph)

The base fuel able is your master table. It tells you how much fuel in lbs/hr the injector will discharge at a given MAP kPa or TPS reading at a particular RPM. This information is created through learning or the base calibration steps depending on where you’re at in the tuning process. These numbers work in conjunction with your target air fuel ratio on a separate graph. Here you can see what parts of the graph represent what engine scenario. This is extremely helpful in tuning out and bugs you may come across during a dyno pull or driving. Since it’s unlikely you will experience each field in the base map during learn, you may pick up some peaks and valleys. Holley EFI has a smoothing feature that takes a highlighted area and levels out the highs and lows. Highlighted selections can also be adjusted by any present so you don’t need to change each one individually. This view will also warn you if you have requested more fuel than your fuel system can supply so you don’t run into unexpected trouble.  The base fuel table is automatically tuned by the learning feature, or can be tuned manually.


Basic Input/Outputs and Pin Mapping

The Dominator ECU has 47 programmable input and 36 output pins. These inputs can be configured for 12V, Ground, Digital Speed, IPU Speed, 5V, 20V, and Thermistor types. The outputs can be configured as +12V, Ground, or +12V and Ground Pulse Width Modulated (PWM) types.  These pins can be configured to do anything from sensing transbrake engagement, to lighting an idiot light, to the creation of an all-out data acquisition system. There are some pins that are already configured as fuel pump triggers, electric fan controls, A/C override and IAC kick.


Spark Control

The first step for ignition setup is to fill out the Ignition Parameters section where the ignition type is designated. This menu also sets the firing order, knock sensor parameters (if used), cranking timing parameters, and the rev limiters. The Dominator EFI system has three rev limiters with four cutout options. The main over-rev limiter keeps your engine from, obviously, over revving. The other two limiters are setup based on a programmable input signal for launching or burnouts. The limiting types are Fuel Only which performs a “hard cut” of fuel flow only when the high RPM is hit.  “Hard cut” happens when fuel flow is stopped to all cylinders until the main low RPM setting is met. The limiting types start with Spark Only where a “hard cut” of ignition to all cylinders only when the high RPM is hit and continues until the low RPM entry is reached. The Fuel and Spark type is where a “hard cut” of ignition and fuel flow occur when the high RPM limit is hit. The Soft type uses “soft cut” of ignition from individual cylinders as needed to bring the engine back to the low RPM limit. If the high RPM limit is reached despite the soft cut, a hard cut will be implemented. Like the base fuel map, the spark map can be viewed and adjusted in a table or a graph form at 16X16 or the high-resolution 30X30 fields. The base calibration will start you off in the right direction, but you can make adjustments as you wish to the main table and to compensations due to knock or temperature.


Drive by Wire

Dominator EFI is an excellent choice for LS engines because they can control one or even two drive by wire throttle bodies. The first step is to match your DBW to one of the GM, Ford, or Nissan throttle bodies listed in the DBW Parameters window. With this information the ECU can adjust the pedal to throttle position relationship. This setting drastically changes the way your car will feel. A direct 1:1 relationship will give you a responsive but predictable feel. A steeper curve will make the car feel light on its feet, but can get you into trouble if you’re not expecting it. A flatter curve will give it a sluggish feel, perfect for when you’re letting someone borrow your ride.





This ECU really does it all with a four-stage progressive nitrous controller built in. Each stage supports wet non-progressive, wet progressive, dry non-progressive, or dry progressive types. In the Nitrous Parameters area you will enable each stage, the TPS trigger point, and lean and rich cutoff AFRs. In each stage’s setup page are controls for nitrous type (wet/dry, progressive, non-progressive) RPM trigger and cut off, delay, closed loop settings, and progressive control if desired. The progressive control can be either time or RPM based, the time based often being used to reduce power early in a ¼-mile pass for better traction. Each nitrous stage as a separate timing retard control that can be sequenced with progressive nitrous ramps to keep the engine at optimal timing. Using a dry nitrous system is often preferred because of the more precise fuel compensation that a nitrous nozzle can’t achieve. The ECU will compensate with extra fuel to maintain the correct AFR even if you’ve neglected to program it that way. That is one of the benefits of closed loop operation, instant compensation that can save your engine. Progressive pulse speed is also adjusted here from 10-35Hz.




The sole purpose of water injection is to cool the incoming air/fuel mixture while the purpose of methanol is to add an equal part of a combustible material. The Dominator EFI system is unique in that you can program what percentage of water/methanol flow you desire, as a function of fuel injector flow. This allows for precise tuning based on engine RPM and load and for the engine not to be over- or under-injected. This being said, you must use Holley W/M solenoids and nozzles as they are flow characterized for this method.




The Boost Control, which is the final phase of testing before being released, has all the features of stand-alone boost controllers, and more.  Boost can be controlled vs time, speed, engine RPM, or can be controlled vs time or speed in each gear!  Multiple control strategies will be offered that allow the control of the waste gate dome pressure, or control of the actual manifold pressure (boost) itself, both in open or closed loop modes.



Data Logs

Data logging is extremely useful for not only reviewing race history, but for trouble shooting as well. Holley EFI can perform both PC and internal (when a laptop can’t be present) logging. The number of items being logged as well as the rate of logging can be adjusted in the Datalog dropdown. Logging can be triggered by an engine start, immediately with an adjustable max on time, or triggered. It can be triggered by any input including RPM, TPS, nitrous activation, oil pressure reading, or a toggle switch just to name a few. Holley EFI has a data overlay feature which allows for a data log to be traced on any screen in the tuning software.  The internal logger has a huge 2GB of memory, and samples all channels up to 100 samples per second.   This high sampling rate can be helpful when trying to diagnose a malfunctioning sensor. Each view can be saved separately for quick reference.