FAST EZ EFI: Carb to Injection Made Easy

The Quest for Modern Drivability

For decades, the rumble of a carbureted engine has been the soundtrack to automotive passion. However, as modern automotive technology advances, the benefits of electronic fuel injection (EFI) – such as improved fuel economy, better throttle response, and easier cold starts – are becoming increasingly attractive, even to owners of classic vehicles. Traditionally, converting a carbureted car to EFI was a complex and often daunting task, requiring extensive knowledge of tuning, sophisticated diagnostic equipment, and a significant time investment. This process was typically reserved for experienced mechanics and tuning experts. However, a groundbreaking product from FAST has dramatically simplified this conversion: the EZ EFI system. This innovative system promises to bring the advantages of fuel injection to a wider audience, making the transition from carburetion a remarkably straightforward process.

From Carburettors to EFI: A Paradigm Shift

The appeal of fuel injection lies in its precision. Unlike carburetors, which rely on mechanical adjustments and atmospheric conditions to deliver fuel, EFI systems use sophisticated sensors and a computer (ECU) to precisely control the amount of fuel delivered to the engine. This precise control translates into tangible benefits for the driver. Fuel injection systems can adapt to changing conditions in real-time, optimising the air-fuel ratio for various engine loads and speeds. This leads to:

• Improved Fuel Efficiency: More precise fuel delivery means less wasted fuel, resulting in better mileage.
• Enhanced Drivability: Smoother idle, improved throttle response, and easier cold starts are hallmarks of EFI.
• Lower Emissions: More efficient combustion leads to cleaner exhaust gases.
• Greater Power Potential: EFI systems can be tuned to maximise performance under various conditions.

Historically, achieving these benefits meant a significant learning curve. Tuning a carburetor, while achievable for many enthusiasts, can be a time-consuming process involving fiddling with jets, needles, and accelerator pumps. EFI tuning, on the other hand, traditionally involved understanding complex software and making intricate adjustments to fuel maps, ignition timing, and countless other parameters. This is where the FAST EZ EFI system aims to change the game.

The FAST EZ EFI: Simplifying the Conversion

The core innovation of the FAST EZ EFI system is its self-tuning capability. This technology allows the system to automatically adjust and optimise its parameters as you drive, effectively creating a custom fuel map for your specific engine and driving style without the need for constant manual intervention. This is a significant departure from traditional EFI systems, which often require extensive dyno tuning or hours spent on the street making adjustments.

Our Test Subject: The "Riced Rat Rod"

To demonstrate the ease of the EZ EFI conversion, we looked at the experience with a Nissan 240SX, affectionately nicknamed the "Riced Rat Rod." This particular vehicle, originally a factory fuel-injected car, had been modified to run a carbureted 400ci small-block Chevy. Despite its light weight and a potent Tremec TKO-600 transmission, delivering 425 horsepower to the rear wheels, the carbureted setup presented some compromises in daily drivability. The goal was to make this moderately-cammed Chevy more user-friendly for street use by returning it to fuel injection, but this time with the modern advantages of EFI.

The EZ EFI Master Kit: Everything You Need

For this conversion, the EZ EFI Master Kit was chosen. This comprehensive package includes not only the core EZ EFI throttle body and ECU but also essential components such as a fuel pump, fuel filter, fuel lines, fittings, a wiring harness, a fuel pressure regulator, and a fuel pressure gauge. While the EZ EFI system can be purchased without the master kit, the latter simplifies the installation considerably by providing all the necessary, compatible parts. A crucial requirement for the EZ EFI system is a return-style high-pressure fuel system, as the low-pressure systems used with carburetors are not suitable.

Installation: A Step-by-Step Overview

The installation process for the FAST EZ EFI is designed for simplicity:

1. Throttle Body Installation: The FAST throttle body is designed to bolt directly onto the same mounting points as a traditional 4150-style 4-barrel carburetor. Even the throttle return spring can be a direct fit.
2. Sensor Connections: All electrical connections are clearly labelled. The wide-band O2 sensor, crucial for the self-tuning function, is installed in the header collector. If a similar sensor system was already in place, it simply involves plugging in the new connector. The coolant temperature sensor is installed in the intake manifold.
3. Wiring Harness: The wiring is remarkably straightforward. Heavy-gauge power and ground wires connect directly to the battery to prevent electrical noise. The Master Kit includes a plug-and-play fuel pump relay harness. The RPM input signal, vital for the ECU, connects directly to the ignition box output, with an included signal converter for HEI-equipped vehicles. The remaining connections include a serial cable for the display, a display power connection, and a wire to a 12-volt switched source to power the ECU. Provisions are also included for features like A/C idle-up and electric fan control.
4. Fuel System: The new high-pressure fuel pump replaces the old low-pressure unit. Supply and return fuel lines are run, with the pump harness connecting to the EZ EFI fuel pump harness. Additional fittings may be required depending on the fuel cell setup. Wrapping fuel lines in heat-resistant sheathing is recommended to keep the fuel cool.

Initial Setup and First Start

Once all connections are made and the fuel system is plumbed, the initial setup begins. The EZ EFI features a simple menu-driven wizard that prompts the user for essential information, such as engine size, desired idle speed, fuel pressure, and cylinder count. The system then guides the user through calibrating the throttle position sensor (TPS) at idle and wide-open throttle. With the initial setup complete, the engine is cranked over, and in most cases, it fires up almost instantly. The display provides a target window for setting the idle speed using the throttle body's idle set screw, similar to a carburetor.

The Magic of Self-Tuning

The true brilliance of the EZ EFI system lies in its ability to learn and adapt while you drive. The ECU continuously monitors the engine's performance via the wide-band O2 sensor, comparing the actual air-fuel ratio to a pre-programmed target. Based on this comparison, it makes real-time adjustments to the fuel delivery, gradually building a sophisticated fuel map that optimises performance across various operating conditions. This means that as you drive, the engine becomes progressively smoother and more responsive.

Tuning Tweaks: Fine-Tuning the Experience

While the EZ EFI handles the bulk of the tuning, there are opportunities for fine-tuning. For instance, in the "Riced Rat Rod" test, it was observed that during light throttle situations, the engine tended to run slightly rich. The system offers an "accel fuel" adjustment, similar to an accelerator pump on a carburetor. By slightly reducing this setting, the bogging under light throttle transitions was eliminated, resulting in perfect drivability.

An Interview with David Page, FAST EZ EFI Engineer

To gain deeper insight into the technology, we spoke with David Page, the engineer behind the FAST EZ EFI system.

powerTV: For those unfamiliar with EFI, a self-tuning system seems almost magical. Can you explain how it works?

David Page: "It's based on closed-loop operation, which isn't new. The system uses a wide-band O2 sensor to compare the target air-fuel ratio set in the ECU to the actual air-fuel ratio the engine is producing. It then makes corrections to match these two values. What's unique about the EZ EFI is that it takes these correction percentages and uses them to build a fuel map. Essentially, it creates a new map tailored to that specific engine and application, aiming for near-zero correction factors."

powerTV: The EZ EFI uses fewer sensors than a factory computer but gains accuracy with a wide-band O2 sensor. What's the biggest difference between engineering a universal kit like this versus an OEM application?

David Page: "The wide-band sensor is a key differentiator. OEM systems spend thousands of hours calibrating each application. They can use a narrow-band sensor because their calibration is so precise for a specific use. Our EZ EFI system needs to be adaptable to a vast range of engines, from a 302 cubic inch street car to a 500 cubic inch airboat engine. The wide-band sensor provides a much wider tuning window, allowing the system to adapt effectively across diverse loads and RPM ranges."

powerTV: How does the EZ EFI differ from high-end standalone systems like the XFI?

David Page: "The EZ EFI uses the same primary sensors found in high-end systems, and some sensors are shared. The main difference is that the EZ EFI does not control ignition, which allows us to offer it at a more affordable price point. It also prioritises simplicity. The ignition system remains largely untouched, with only the RPM input wire needing connection."

powerTV: During the setup wizard, how does the computer tailor the initial tune for different engine combinations?

David Page: "The EZ EFI is a true speed-density application. It estimates the mass of air entering the engine based on volume and density. Knowing the engine's potential air volume (e.g., 400 cubic inches) and the target air-fuel ratio, it calculates the required fuel mass by adjusting injector pulse width. Changing the engine displacement number is a key variable in the ECU's programming."

powerTV: The RPM input is critical. Why is the engine unable to run without it?

David Page: "RPM has the biggest impact on fueling changes. Without RPM data, the ECU can only calculate a single pulse width – the idle value. This value, if applied during acceleration, would prevent the engine from running. Conversely, a pulse width suitable for part throttle would flood the engine at idle. It's like trying to run a carburetor with only main jets or only idle circuits."

powerTV: What are your top tips for getting the EZ EFI to learn a vehicle properly?

David Page: "The more varied your driving, the better. Hit the streets and let the system learn. You can feel and hear the engine smoothing out as it refines its map. For low idle vacuum situations, let the system learn the idle first. Wide-open throttle is the easiest part for the ECU to learn – a few wide-open throttle blasts are usually sufficient. Drive in the RPM ranges and situations you most frequently encounter."

powerTV: What is the reason for the 600 horsepower limit, and can it run alternative fuels?

David Page: "The limit is primarily due to the four 88 lb/hr injectors on the system, which are limited by their compact size. Higher flow rate injectors can alter fuel distribution and atomisation. While the system could function with E85, the horsepower would be limited to about 300hp due to the increased fuel volume needed. Currently, there is no custom fuel mapping for E85."

powerTV: Are there any special considerations for engine modifications like intakes, heads, or cams?

David Page: "The EZ EFI works with both single and dual-plane manifolds, but dual-plane manifolds offer better fuel distribution. With aggressive cams that result in low idle vacuum (less than 7-8 inches), patience is key during the idle fuel curve learning process. It's advisable to set the initial target idle higher and then gradually lower it."

powerTV: What changes are involved when moving to a dual quad setup with four EZ EFI throttle bodies?

David Page: "The primary difference is the addition of four more injectors, bringing the total to eight. This effectively halves the pulse width required for each injector. That's the only significant programming change."

powerTV: With FAST covering both high-end (XFI) and entry-level (EZ EFI) markets, do you see a middle-ground product, perhaps with integrated ignition control?

David Page: "We are definitely planning a new product in that area. The self-tuning functionality will be carried over to all future ECUs, including high-end systems. We welcome input from the community on what they perceive as essential features in that market segment."

EZ Does It in One Day

The FAST EZ EFI system represents a significant leap forward in making the transition from carburetion to fuel injection accessible to a much broader range of automotive enthusiasts. Its intuitive setup wizard and powerful self-tuning capabilities eliminate the need for expensive tuning sessions and complex laptop-based adjustments. By simply answering a few basic questions, owners can unlock the benefits of modern fuel injection, enjoying improved performance, better fuel economy, and enhanced drivability. The system truly lives up to its name, making EFI conversion an achievable and rewarding project, often completed in a single day.

Frequently Asked Questions

The FAST EZ EFI system is a testament to how modern technology can simplify complex automotive modifications, bringing the advantages of fuel injection within reach for a wider audience of enthusiasts.

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