Transforming Holley Terminator Efi Fuel System: A Comprehensive Guide

The Holley Terminator EFI throttle body injection system is a modern, self-learning electronic fuel injection system that offers a simple upgrade from a carburetor. The Terminator EFI system is designed to be user-friendly and does not require a laptop for tuning. With a self-learning function, the system compensates for different conditions and adjusts itself while you drive, resulting in improved mileage, drivability, and cold-start performance. The installation process is straightforward, with a detailed instruction manual included, and the throttle body has four throats, similar to a Holley four-barrel carburetor, making it a suitable replacement. Holley offers a range of EFI systems, from basic kits to high-end racing options, and the Terminator EFI stands out for its ease of use and installation.

Converting from a carburetor to electronic fuel injection

Step 1: Remove the Carburetor

Begin by removing the fuel lines and hoses connected to the carburetor. Use a wrench to detach the carburetor from the manifold by unscrewing the nuts holding it in place. If the carburetor is in good condition, you can consider selling it as a used part; otherwise, it's bound for the junkyard.

Step 2: Install the Injectors

The next step is to install injectors into the intake manifold. This step may require welding, so you might need to take your vehicle to a machine shop. Most intake manifolds can be modified by welding injector bungs. Once the injector spots are prepared, slide in the injectors with o-rings for a tight seal. Additionally, you'll need to install injection fuel rails, which may also need to be machined. Depending on the conversion kit you choose, it may provide a ready-to-go manifold that accepts injectors.

Step 3: Install the Throttle Body

Install a throttle body to regulate the airflow into the engine valves. Universal throttle body models are typically the most straightforward option for conversions. Bolt the throttle body in place and connect it to the throttle linkage, which is linked to the accelerator pedal. Don't forget to include an idle air controller (IAC) with the EFI throttle body. The IAC modulates airflow by opening or closing a small passage based on the manifold's air requirements. Most throttle bodies come with an IAC already installed.

Step 4: Install the Sensors

For the EFI system to function optimally, it needs to monitor and adjust fuel injection based on various measurements. Install the necessary sensors, including an oxygen sensor, manifold air pressure sensor, air temperature sensor, coolant sensor, and throttle position sensor. These sensors are generally easy to install, as they usually screw directly into the engine. Ensure that your kit contains all the required sensors; if not, you may need to purchase additional sensor packages.

Step 5: Adjust the Distributor

Since the new EFI system will control the ignition timing and advance, you'll need to lock out the timing, vacuum, and mechanical advance settings on the distributor. In most cases, a bank-to-bank EFI system won't require any further adjustments to the distributor. However, if you opt for a sequential fuel injection system, you may need to upgrade to a dual sync distributor.

Step 6: Set Up the Electronics

The electronics are the heart of your new EFI system. The easiest approach is to acquire an aftermarket EFI system, as reprogramming a factory control unit can be extremely challenging. Aftermarket systems come with all the necessary components, and you can customize the settings by connecting the computer to a laptop. Mount the EFI system and plug it in using a wiring harness. Fine-tune the settings to achieve your desired performance, and your vehicle is now ready to hit the road!

Additional Considerations:

It's important to note that converting to EFI requires a significant upgrade to your fuel system. Electronic fuel injection operates at much higher fuel pressures than carburetors (around 40-60 psi compared to 5-7 psi for carburetors). Therefore, you'll need to install a new fuel pump capable of delivering sufficient fuel pressure and volume. Additionally, most EFI systems require a return line from the regulator back to the fuel tank. EFI systems are also highly sensitive to debris and contaminants in the fuel, so ensure you have adequate fuel filters in place.

Choosing the right Terminator EFI kit

• Engine Type: The Terminator EFI kit is designed for engines with an intake manifold that can accommodate a 4-barrel carburetor. If you have a different engine configuration, other Holley EFI options may be more appropriate.
• Ease of Installation and Use: The Terminator EFI kit stands out for its user-friendliness. It doesn't require a laptop for tuning and has a self-learning function that adjusts to different conditions as you drive. This makes it a good choice for those seeking a straightforward installation and hassle-free driving experience.
• Horsepower Considerations: While the Terminator EFI kit can handle up to 600 horsepower, if you're aiming for higher horsepower outputs, you may need to consider other options or upgrade the injectors.
• Advanced Capabilities: The Terminator EFI is suitable for naturally aspirated V8 engines. However, if you require advanced capabilities such as V6 applications, transmission control, or boosted applications, you might want to explore the Holley Sniper EFI or other specialized kits.
• Visual Preferences: The Terminator EFI kit offers a modern, electronic fuel injection system while retaining the classic carburetor look with its Double-Pumper-style EFI throttle body, known as the Terminator Stealth.
• Transmission Control: If you need transmission control capabilities, the Terminator EFI kit with the Dominator ECU is the way to go. It includes transmission control for specific applications, such as GM 4L60E or 4L80E transmissions.
• Ignition Timing Control: The Terminator EFI system can control ignition timing when used with a Ford TFI distributor. However, if you have other ignition system requirements, you may need to consider a different kit or make additional adjustments.
• Budget Constraints: The Terminator EFI kit offers a balance between functionality and affordability. If you're on a tighter budget, the Holley Sniper EFI might be a more cost-effective solution, although it has a lower horsepower threshold.
• Self-Tuning Capability: One of the standout features of the Terminator EFI kit is its self-tuning capability. It learns and adjusts fuel and spark settings as you drive, eliminating the need for constant manual tuning.
• Laptop Requirement: Unlike some other EFI kits, the Terminator EFI does not require a laptop for tuning. The included handheld controller allows for basic tuning and setup, making it ideal for those who want a simpler, less technical approach.

When choosing the right Terminator EFI kit, it's essential to consider your specific engine configuration, desired level of control, and any unique requirements your project may have. Additionally, keeping in mind your budget and the level of technical expertise you're comfortable with will help guide your decision.

Installing the throttle body

The throttle body has four throats, similar to a Holley four-barrel carburettor, and flows 950cfm, which is good for 600 horsepower according to Holley. The 4150-style flange means it bolts right in place of a typical Holley carb. The throttle body has four 80lb/hr fuel injectors already installed, two each on what would be the "primary" and "secondary" sides of a carburettor. Also visible here in the throttle bores (note the tiny holes around the bore) are the patent-pending annular discharge fuel rings. According to Holley, these are for maximum flow and atomization, and because the injectors fire right into these passages, there are no delays as with a carburettor booster venturi.

Can you remove and install a carburettor? Then you can install the Holley throttle body. We used an inexpensive 1-inch spacer between the throttle body and Edelbrock intake, which proved to be an issue (see later in the story).

Electronic fuel injection works with much higher fuel pressure than a carburettor (40-ish psi compared to the carb's 5 to 6 psi), so you must use an entirely new fuel system. Holley has complete fuel-system kits, some even packaged with the EFI system. The company offers a lot of options for both, depending on your application. We chose the Dominator inline pump and regulator.

The fuel system requires a return line from the regulator back to the tank, so we modified a new stock fuel tank for a -10 feed line (in the stock flange) and an -8 return, which required a bung welded into the tank. Don't do this with a used tank unless you know what you're doing, or I predict a big, painful bang in your future. It's why we started with a new tank that never had fuel in it before.

We mounted the pump to the underside of the floor, on the passenger side next to the subframe connector. Note, you must also make custom-length fuel hoses, which are included in Holley's fuel system kits.

We mounted the Dominator billet EFI bypass fuel-pressure regulator on the passenger-side shock tower. One fuel line feeds the throttle body/injectors, and the return line exits the regulator at the bottom and goes back to the fuel tank. The electrical connection tells the EFI computer the fuel pressure.

Once the fuel lines are routed and hooked up, it's a good time to test for leaks. With a few gallons of gas in the tank and jumper wires routed to a battery, get the pump running and check all the connections for leaks.

The EFI computer can be mounted in the engine compartment, if you're careful to keep it away from heat and moisture. However, it's a much better idea to mount it inside the car. We mounted ours on the passenger-side footwell, next to the kick panel.

Setting up the fuel system

The Holley Terminator EFI Throttle Body Injection System is a user-friendly system that can be used to convert from a carburetor to modern, self-learning electronic fuel injection. The system comes with a 30-page instruction manual that details how to make fuel lines and assemble hose ends, so it's relatively simple to install.

Electronic fuel injection works with much higher fuel pressure than a carburetor (around 40 psi compared to a carb's 5-6 psi), so you must use an entirely new fuel system. Holley offers complete fuel-system kits, some even packaged with the EFI system. The company provides a lot of options depending on your application.

For example, you can choose the Dominator inline pump and regulator. The fuel system requires a return line from the regulator back to the tank, so you will need to modify your fuel tank. Don't do this with a used tank unless you are certain it is safe to do so. It is recommended to start with a new tank that has never had fuel in it before.

Mount the pump to the underside of the floor, and make custom-length fuel hoses, which are included in Holley's fuel system kits. Mount the regulator on the passenger-side shock tower. One fuel line feeds the throttle body/injectors, and the return line exits the regulator and goes back to the fuel tank. The electrical connection tells the EFI computer the fuel pressure.

Once the fuel lines are routed and hooked up, test for leaks. With a few gallons of gas in the tank and jumper wires routed to a battery, get the pump running and check all the connections for leaks.

Tuning the system

The Terminator EFI Throttle Body Injection System is designed to be user-friendly and does not require a laptop for tuning. The system has a self-learn function that compensates for different conditions and automatically tunes itself while you drive.

To begin the tuning process, use the small handheld controller to set the basic calibration. The system will prompt you to input some basic information, such as engine cubic inches, rough camshaft timing, target air/fuel ratio, and whether the computer is controlling ignition timing.

Once the basic calibration is set, it is time to drive the car and allow the system to perform its self-tuning process. For best results, drive under a variety of operating conditions, with different engine speeds and loads. Rev the engine slowly in neutral and hold it at different speeds, up to 2,500 rpm. Drive the car using different transmission gears so the system can learn in different areas. If you have an automatic transmission, you may want to put it in gear and apply a small amount of throttle while your foot is on the brake pedal.

There are several conditions in which the Terminator EFI system's self-learning will not occur:

• When the engine is below 160 degrees Fahrenheit.
• When the engine experiences quick accelerator pedal movement.
• At certain times when the accelerator pedal is lifted and the vehicle is coasting.
• When the learning function is disabled by the user.

In addition to fuel management, the Holley Terminator system can also control ignition timing and a modern automatic transmission. However, these functions require additional setup and may not be supported by all vehicle models.

For more advanced tuning, Holley offers an adapter that connects the Terminator EFI system to a laptop, providing access to minor trim changes that are not possible with the handheld controller alone. This allows users to experiment with fine-tuning and customization beyond the basic self-learning capabilities of the system.

Frequently asked questions