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WAVEFORMS - INJECTOR PATTERN TUTORIAL 1998 Mitsubishi Montero GENERAL INFORMATION Waveforms - Injector Pattern Tutorial * PLEASE READ THIS FIRST * NOTE: This article is intended for general information purposes only. This information may not apply to all makes and models. PURPOSE OF THIS ARTICLE Learning how to interpret injector drive patterns from a Lab Scope can be like learning ignition patterns all over again. This article exists to ease you into becoming a skilled injector pattern interpreter. You will learn: * How a DVOM and noid light fall short of a lab scope. * The two types of injector driver circuits, voltage controlled & current controlled. * The two ways injector circuits can be wired, constant ground/switched power & constant power/switched ground. * The two different pattern types you can use to diagnose with, voltage & current. * All the valuable details injector patterns can reveal. SCOPE OF THIS ARTICLE This is NOT a manufacturer specific article. All different types of systems are covered here, regardless of the specific year/make/model/engine. The reason for such broad coverage is because there are only a few basic ways to operate a solenoid-type injector. By understanding the fundamental principles, you will understand all the major points of injector patterns you encounter. Of course there are minor differences in each specific system, but that is where a waveform library helps out. If this is confusing, consider a secondary ignition pattern. Even though there are many different implementations, each still has a primary voltage turn-on, firing line, spark line, etc. If specific waveforms are available in On Demand for the engine and vehicle you are working on, you will find them in the Engine Performance section under the Engine Performance category. IS A LAB SCOPE NECESSARY? INTRODUCTION You probably have several tools at your disposal to diagnose injector circuits. But you might have questioned "Is a lab scope necessary to do a thorough job, or will a set of noid lights and a multifunction DVOM do just as well?" In the following text, we are going to look at what noid lights and DVOMs do best, do not do very well, and when they can mislead you. As you might suspect, the lab scope, with its ability to look inside an active circuit, comes to the rescue by answering for the deficiencies of these other tools. OVERVIEW OF NOID LIGHT |