Volkswagen Corrado (1993 year). Manual - part 215

 

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Volkswagen Corrado (1993 year). Manual - part 215

 

 

VR65 ENGINE: AFFIX NEW VACUUM HOSE ROUTING LABEL 

Sincerely

Folker G. Rieflin
Product Compliance Manager

ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ

END OF ARTICLE

WAVEFORMS - INJECTOR PATTERN TUTORIAL 

         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

WAVEFORMS - INJECTOR PATTERN TUTORIAL 

         OVERVIEW OF NOID LIGHT

         The noid light is an excellent "quick and dirty" tool. It can
usually be hooked to a fuel injector harness fast and the flashing
light is easy to understand. It is a dependable way to identify a no-
pulse situation.
         However, a noid light can be very deceptive in two cases:

      *  If the wrong one is used for the circuit being tested.
         Beware: Just because a connector on a noid light fits the
         harness does not mean it is the right one.
      *  If an injector driver is weak or a minor voltage drop is
         present.

         Use the Right Noid Light
         In the following text we will look at what can happen if the
wrong noid light is used, why there are different types of noid lights
(besides differences with connectors), how to identify the types of
noid lights, and how to know the right type to use.
         First, let's discuss what can happen if the incorrect type of
noid light is used. You might see:

      *  A dimly flashing light when it should be normal.
      *  A normal flashing light when it should be dim.

         A noid light will flash dim if used on a lower voltage
circuit than it was designed for. A normally operating circuit would
appear underpowered, which could be misinterpreted as the cause of a
fuel starvation problem.
         Here are the two circuit types that could cause this problem:

      *  Circuits with external injector resistors. Used predominately
         on some Asian & European systems, they are used to reduce the
         available voltage to an injector in order to limit the
         current flow. This lower voltage can cause a dim flash on a
         noid light designed for full voltage.
      *  Circuits with current controlled injector drivers (e.g. "Peak
         and Hold"). Basically, this type of driver allows a quick
         burst of voltage/current to flow and then throttles it back
         significantly for the remainder of the pulse width duration.
         If a noid light was designed for the other type of driver
         (voltage controlled, e.g. "Saturated"), it will appear dim
         because it is expecting full voltage/current to flow for the
         entire duration of the pulse width.

WAVEFORMS - INJECTOR PATTERN TUTORIAL 

      *  Systems with a voltage controlled injector driver. Another
         way to say it: The noid light is designed for a circuit with
         a "high" resistance injector (generally 12 ohms or above).
      *  Systems with a current controlled injector driver. Another
         way to say it: The noid light is designed for a circuit with
         a low resistance injector (generally less than 12 ohms)
         without an external injector resistor.
      *  Systems with a voltage controlled injector driver and an
         external injector resistor. Another way of saying it:  The
         noid light is designed for a circuit with a low resistance
         injector (generally less than 12 ohms) and an external
         injector resistor.

NOTE:    Some noid lights can meet both the second and third
         categories simultaneously.

         If you are not sure which type of circuit your noid light is
designed for, plug it into a known good car and check out the results.
If it flashes normally during cranking, determine the circuit type by
finding out injector resistance and if an external injector resistor
is used. You now know enough to identify the type of injector circuit.
Label the noid light appropriately.
         Next time you need to use a noid light for diagnosis,
determine what type of injector circuit you are dealing with and
select the appropriate noid light.
         Of course, if you suspect a no-pulse condition you could plug
in any one whose connector fit without fear of misdiagnosis. This is
because it is unimportant if the flashing light is dim or bright. It
is only important that it flashes.

 

 

 

 

 

 

 

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