26/02/2015
The Evolution of Fuel Delivery: From Carburettors to EFI
For decades, the humble carburettor was the heart of most petrol engines, meticulously mixing air and fuel to achieve combustion. However, as automotive technology advanced, so did the demand for greater efficiency, power, and emissions control. This evolutionary leap led to the widespread adoption of Electronic Fuel Injection (EFI) systems, a sophisticated method of delivering fuel that offers significant advantages over its mechanical predecessor. In its most fundamental form, an EFI system utilises an Electronic Control Unit (ECU), often referred to as the engine's brain, to precisely meter the amount of fuel injected into the engine's intake manifold or directly into the cylinders. This precise control is achieved by the ECU continuously analysing various sensor inputs, such as engine speed, throttle position, air temperature, and manifold pressure. Based on this data, it consults pre-programmed fuel maps stored within its memory to determine the optimal fuel delivery for any given operating condition. This intelligent approach to fuel management results in improved fuel economy, lower emissions, and enhanced engine performance. The FAST™ EZ-EFI® 2.0 system represents a modern advancement in this technology, offering a self-tuning capability that simplifies the conversion from carburetted systems to the benefits of EFI.
How Does a Basic EFI System Work?
At its core, an Electronic Fuel Injection system operates by comparing real-time engine data with pre-programmed "base fuel tables" stored within the ECU. These tables are essentially sophisticated maps that dictate how much fuel should be injected for a specific engine speed and load. The ECU receives a constant stream of information from various sensors positioned throughout the engine and vehicle. Key among these are:
- Engine Speed (RPM): Measured by a crankshaft position sensor, this tells the ECU how fast the engine is rotating.
- Engine Load: This can be determined through various means, such as manifold absolute pressure (MAP) sensors or throttle position sensors (TPS), indicating how hard the engine is working.
- Airflow/Manifold Pressure: Sensors like the MAP sensor measure the amount of air entering the engine.
- Throttle Position: The TPS informs the ECU how much the driver is requesting through the accelerator pedal.
- Air and Coolant Temperatures: These sensors help the ECU adjust fuel delivery for optimal performance in varying environmental conditions.
By cross-referencing these inputs with its internal fuel maps, the ECU calculates the precise duration for which the fuel injectors should remain open. This injector pulse width directly controls the amount of fuel sprayed into the engine. The system is designed for continuous optimisation, meaning it can adapt to changing conditions to maintain the ideal air-fuel ratio for combustion. This adaptive capability is a significant advantage over carburettors, which are less responsive to dynamic changes in engine operation or environmental factors.
Introducing the FAST™ EZ-EFI® 2.0 System
The FAST™ EZ-EFI® 2.0 system is designed to bring the advantages of modern fuel injection to a wide range of vehicles, particularly those that were originally equipped with carburettors. It offers a user-friendly, self-tuning approach, making the transition to EFI more accessible. The kit typically includes a precisely engineered throttle body that replaces the carburettor, an ECU module, a handheld tuning device, and all the necessary sensors and wiring harnesses for a comprehensive installation. The self-tuning nature of the EZ-EFI® system means that after the initial setup, the ECU will actively learn and adapt to the specific engine's characteristics, optimising fuel delivery for improved performance, drivability, and fuel efficiency without the need for extensive manual tuning.
Key Components of the EZ-EFI® 2.0 System:
| Component | Description |
|---|---|
| Throttle Body Assembly | Replaces the carburettor, housing the fuel injectors and throttle plate. Features multiple vacuum ports for various engine accessories. |
| ECU Module | The "brain" of the system, processing sensor data and controlling fuel delivery and ignition timing (optional). |
| Touchscreen Handheld Unit | Provides a user interface for setup, monitoring live data, and making adjustments. |
| Wiring Harnesses | Connects all sensors, the ECU, and the fuel pump. Specific harnesses are included for different fuel system configurations. |
| Sensors | Includes essential sensors like Coolant Temperature, Wideband Oxygen Sensor (O2), and Fuel Pressure sensors for accurate engine monitoring. |
Installation Considerations for EZ-EFI®
The installation of an EFI system like the FAST™ EZ-EFI® 2.0 involves several critical steps, ensuring the system functions correctly and safely. A thorough understanding of your vehicle's existing systems is paramount.
Essential Preparations:
- O2 Sensor Bung: A wideband oxygen sensor is crucial for the EFI system to monitor and adjust the air-fuel ratio. This requires welding an O2 sensor bung into the exhaust system, ideally upstream of the catalytic converter. If you lack welding capabilities, a qualified exhaust shop can perform this task. Remember to use the provided O2 plug to protect the sensor if the exhaust is temporarily exposed.
- Fuel System Upgrade: EFI systems operate at significantly higher fuel pressures than carburetted systems. A fuel injection-rated fuel system, including a high-pressure fuel pump and compatible fuel lines, is essential. Kits like the 30401-KIT (Master In-Tank) and 30402-KIT (Master In-Line) often include these necessary components.
- Vacuum Lines: The EZ-EFI® throttle body has multiple vacuum ports. Ensure you correctly connect vacuum-operated accessories, noting whether they require manifold or ported vacuum. A "return-style" fuel system will necessitate an 1/8" vacuum port for the fuel pressure regulator.
- Carburettor Flange/Intake Manifold: The EZ-EFI® throttle body is designed for a four-barrel, square bore flange. If your intake manifold uses a different pattern, an adapter or a new manifold may be required.
- Throttle Linkage and Return Springs: Ensure your existing throttle cable and return spring system are compatible with the new throttle body. A Holley-style system is generally compatible, but a dedicated kit might be necessary for optimal function.
- Ignition System Compatibility: For ignition timing control, the EZ-EFI® requires a consistent crank reference signal. This can be achieved with a crank trigger or a "locked out" distributor with an integrated pickup. A Capacitive Discharge (CD) style ignition box is also required for timing control. If not controlling timing, a clean digital tach output signal from an aftermarket ignition is recommended.
- Spark Plugs and Wires: Non-resistor spark plugs and solid core spark plug wires can interfere with EFI electronics and should be replaced with resistor-type plugs and suppressed wires.
Fuel System Types: Return vs. Returnless, In-Tank vs. In-Line
Choosing the right fuel system configuration is vital for the reliable operation of your EZ-EFI® system. FAST™ generally recommends a "return-style" system for optimal performance and consistency.
- Return-Style: In this setup, fuel is continuously circulated from the tank to the engine and then returned to the tank. A mechanical fuel pressure regulator maintains consistent fuel pressure. This system also helps keep the fuel pump and fuel cooler by circulating fuel.
- Returnless-Style: Fuel is delivered to the engine without a return line. The ECU controls fuel pressure by varying the speed of the fuel pump. This can be simpler in applications where adding a return line is difficult.
- In-Tank Pumps: These are generally preferred due to fewer priming issues and are standard in most modern vehicles. They are also required for returnless systems.
- In-Line Pumps: While sometimes easier to install, they are sensitive to mounting location and must be mounted close to the tank and below its lowest point to ensure proper priming.
Wiring and Sensor Installation:
Proper wiring is crucial for the correct functioning of the EZ-EFI® system. Key connections include:
- Battery Connections: The main battery wires MUST be connected directly to the battery terminals to minimise electrical noise. Use the provided ring terminals and heat shrink for secure connections.
- Switched 12V Source: The "12V SWITCHED" wire must be connected to a source that is live when the ignition is on and during cranking.
- Sensor Wiring: Ensure all sensors, including the Coolant Temperature Sensor and Wideband O2 Sensor, are correctly wired according to the system's diagrams. The O2 sensor should be installed in the exhaust system at least 20 inches from the cylinder head.
- ECU Mounting: Mount the ECU in a location protected from extreme heat and with adequate air circulation. Avoid mounting it close to ignition components to prevent electrical interference.
Tuning and Optimisation with the Handheld Unit
The included touchscreen handheld unit is your primary interface for setting up and fine-tuning the EZ-EFI® system. The system guides you through an initial Setup Wizard to configure essential engine parameters.
Key Setup Wizard Sections:
| Section | Description |
|---|---|
| Engine Parameters | Input engine size (cubic inches), number of cylinders, target idle RPM, and rev limit. |
| Fuel System | Specify fuel type (Gasoline/E85) and delivery method (Return/Returnless). |
| Ignition Type | Configure the system based on your ignition setup (None, FAST™ Crank Trigger, FAST™ Dual-Sync Distributor, etc.) for optimal timing control. |
| Ignition Timing | Set base timing parameters (Idle, All-In, All-In RPM) to create a custom ignition curve. |
| System Selection | Specify if using a single or dual throttle body setup, or other specific configurations like Inglese™ or multiport injection. |
| Injector Specs | Input injector flow rate (lb/hr) and fuel pressure (PSI) for accurate fuel calculations. |
| TPS Calibration | Calibrate the throttle position sensor to ensure accurate throttle input to the ECU. |
| Fuel System Test | Test the fuel pump and pressure to ensure correct operation. |
| Timing Verification | Use a timing light to confirm the ignition timing is accurate and adjust if necessary. |
Advanced Tuning Options:
Beyond the initial setup, the 'Advanced' menu on the handheld unit provides access to further customisation:
- AFR Targets: Adjust the target air-fuel ratio for different operating conditions (Idle, Cruise, WOT) to optimise for fuel economy or power.
- Accel Fuel: Fine-tune the acceleration enrichment to smooth out throttle response, similar to an accelerator pump on a carburettor.
- Fan Control: Set activation temperatures for electric cooling fans.
- IAC Calibration: Calibrate the Idle Air Control (IAC) motor for consistent idle speeds.
Frequently Asked Questions about Fuel Injection
Q1: Why should I switch from a carburettor to fuel injection?
Fuel injection offers superior fuel atomisation, precise fuel metering, and better adaptability to changing conditions. This results in improved fuel economy, lower emissions, smoother idle, better throttle response, and increased power output compared to carburetted systems.
Q2: Is the FAST™ EZ-EFI® 2.0 system difficult to install?
While it requires a good understanding of automotive systems, the EZ-EFI® 2.0 is designed to be user-friendly, especially with its self-tuning capabilities. Comprehensive instructions and support are available from FAST™.
Q3: Do I need to upgrade my fuel pump and lines for EFI?
Yes, EFI systems require higher fuel pressure than carburetted systems. A fuel injection-rated fuel pump, lines, and regulator are essential for proper operation and safety.
Q4: Can the EZ-EFI® system control ignition timing?
Yes, the EZ-EFI® system can control ignition timing when properly configured with compatible ignition components such as a crank trigger or a specific type of distributor. This allows for more precise timing adjustments for optimal performance.
Q5: What is the importance of the Wideband Oxygen Sensor?
The Wideband O2 sensor provides crucial real-time data on the air-fuel ratio in the exhaust. The ECU uses this information to constantly adjust fuel delivery, ensuring the engine runs at its optimal air-fuel ratio for efficiency and performance, and enabling the self-tuning process.
In conclusion, upgrading to an Electronic Fuel Injection system like the FAST™ EZ-EFI® 2.0 is a significant enhancement for any vehicle. It offers a blend of modern technology, improved efficiency, and accessible tuning, transforming the driving experience and unlocking the full potential of your engine.
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