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2.0 Zetec-E in Mk4 Fiesta — ECU

Contents

Introduction

The Engine Control Unit (ECU), also known as a Powertrain Control Module (PCM) or Electronic Fuel Injection (EFI), controls the amount of fuel entering the cylinders depending upon a number of factors including intake air temperature, intake air pressure, exhaust oxygen content, crankshaft speed, throttle position and coolant temperature. Pre-programmed lookup tables, or 'maps', are determined on a rolling road to optimize the fuelling for a combination of fuel economy, even torque characteristics and peak power. It is an example of multiple-input single-output (MISO) nonlinear feedback control.

Most engines produced since the early 1990s are controlled by an ECU, as opposed to a carburettor which mechanically alters the flow of fuel into the cylinders and are preferred by many DIY tuners because they do not contain any electronics. Since the introduction of projects such as Megasquirt, DIY ECUs have become more commonplace and will be used to control the 2.0 Ford Zetec-E engine in my Mk4 Fiesta.

Megasquirt

Two electronic engineers called Bruce Bowling and Al Grippo designed a completely open-source ECU called Megasquirt, providing all schematics, software and application guides for all manner of engines from single-cylinders to mighty V8s. I ordered their V3 PCB and microcontroller, populating the PCB myself from components sourced in the UK from RS Electronics. They also sell a 'stimulator' module to simulate sensor inputs and flash LEDs to represent the injectors, but I built mine from the schematics they provide on their website.

I'll upload some pictures soon.

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