How It Works

A simple, step-by-step explanation of how the CFI Enforcer Classic operates.

The CFI Enforcer Classic is a hybrid fueling system that works with your carburetor, not instead of it. Your carburetor continues to meter airflow and provide baseline fuel, while the ECU adds precision control, supplemental fueling, and optimized ignition timing.
Here’s how the system works in real-world driving.

1. Your Carburetor Still Does the Main Job

The carburetor remains the primary air-metering device. It continues to:

  • Meter airflow

  • Provide baseline fuel

  • Maintain throttle response

  • Preserve the classic look

  • Operate mechanically even if electronics fail

Nothing about the carburetor’s geometry or airflow path is changed.

2. The ECU Adds Supplemental Fuel Only When Needed

The CFI Enforcer uses discreet injection to add fuel in situations where carburetors traditionally struggle:

  • Cold starts

  • Warm-ups

  • Idle stabilization

  • Part-throttle cruising

  • Rapid throttle transitions

  • Temperature and altitude changes

The ECU monitors real-time sensor data and adds just enough fuel to keep the mixture clean, stable, and consistent.

3. Closed-Loop AFR Correction Keeps the Engine on Target

A wideband oxygen sensor constantly measures the air-fuel ratio. The ECU uses this information to:

  • Trim out overly lean areas

  • Prevent lean hesitation

  • Maintain clean, stable combustion

  • Improve mileage

  • Reduce exhaust odor and soot

This is where carburetors fall short.

4. Ignition Timing Is Optimized Automatically

The ECU controls spark timing based on:

  • RPM

  • Engine load

  • Temperature

  • Fuel quality

  • Knock tendency

This improves:

  • Idle quality

  • Throttle response

  • Part-throttle smoothness

  • Fuel economy

  • Overall drivability

You get modern ignition control without installing a full EFI system.

5. A Common Optimization: Leaning the Carburetor Slightly

Many users choose to lean the carburetor’s baseline mixture slightly (main and idle circuits). This is not required — but it is a common and effective method.

Why it works:

  • Carburetors tend to run rich in certain areas

  • The ECU excels at precise, targeted correction

  • Leaning the carb slightly reduces overlap

  • The ECU “fills in the gaps” with clean, accurate fueling

  • The result is smoother operation and cleaner AFR control

This optional approach lets the carburetor handle airflow and broad fueling, while the ECU fine-tunes the mixture with modern precision.

6. Two Fuel-Pressure Modes for Maximum Flexibility

The system can operate in either:

Low-Pressure Mode (3–10 psi)

  • Works with most existing mechanical or electric pumps

  • No return line required (but compatible)

  • No tank modifications

  • Ideal for restorations and street rods

High-Pressure Mode (optional)

  • For users who want maximum injector authority

  • Still does not require a baffled tank

This flexibility is one of the system’s biggest advantages.

7. Cold Starts Become Automatic

When the engine is cold, the ECU provides:

  • Enrichment

  • Idle stabilization

  • Smooth warm-up

  • No choke required

  • No pumping the pedal

Starts feel modern — even on a carbureted engine.
Note: An electric fuel pump must be used for automatic cold starts.

8. Everyday Driving Feels Smoother and More Consistent

During normal driving, the system continuously adjusts fueling and timing to match conditions.

Idle & Warm-Up
Stable, clean, and consistent.

Cruise
Closed-loop correction keeps the mixture efficient.

Acceleration
Supplemental fuel eliminates bogs and flat spots.

9.True Mechanical Fail-Safe

If the ECU or injectors ever stop functioning:

  • The carburetor continues to run mechanically

  • The engine will still start and drive

  • You are never stranded by electronics

This is a major advantage over full EFI systems.

In Summary

The CFI Enforcer Classic blends the strengths of carburetion and electronic control:

  • Carburetor handles airflow and baseline fuel

  • ECU adds precision fueling and spark control

  • Sensors keep the mixture clean and consistent
  • Cold starts and drivability improve dramatically

  • No EFI plumbing or tank modifications required

  • Mechanical fail-safe ensures reliability

  • Optional carb-leaning allows the ECU to fine-tune with maximum precision

It’s a simple, elegant system designed specifically for classic engines.