Administration - Snap-on • Fire procedure • Toilets ... This deflection in the voltage on the falling edge ... The speed of crankshaft rotation affects the

Administration

• Fire procedure

• Toilets

• Breaks

• Mobile telephones – please turn off

Agenda

• Technology development

• ECM logic

• Terminology

• Ignition system analysis

• Engine management systems

• Sensor identification and testing

• Closed loop fuelling

Today’s Petrol Engines

Cam sensor (CKP)

Crank sensor (CMP)

Air flow sensors (AMM/MAF)

Engine coolant sensor (ECT)

Throttle position switch (TPS)

Heated oxygen sensors (HEGO)

Accelerator position (APP)

Map sensor (MAP)

Knock sensor (KS)

Exhaust gas temperature

Fuel temperature sensor

EGR position sensor

Inputs

Ignition coil(s)

Idle speed control valve (ISCV)

Throttle motor

Injectors (petrol or diesel)

Fuel pump

Exhaust gas recirculation valve

(egr)

Turbocharger control

Swirl flaps

VVT control

Variable induction control

Outputs

A BIG INCREASE IN ELECTRONICS!

Today’s Diesel Engines

Inputs Cam sensor

Crank sensor

Air mass meter

Map sensor

Rail pressure sensor

Throttle position

Fuel temperature

EGT

EGR position

DPFE sensor

Outputs Electronic injectors

EGR valves

Additive systems

Inlet metering valves

Pressure regulator

Swirl flaps

Glow plugs

Petrols and Diesels

All controlled by a computer!

Communications

01000110110111001100011

No codes

Codes, no descriptions

Codes and descriptions

ECM Logic

P 0 1 0 0 Setting Conditions System

P = Powertrain

B = Body

C = Chassis

U = Network

Code Type

0 = Generic

1 = Enhanced

2 = Generic

3 = Either

Sub System

1 = Fuel or air

2 = Fuel or air

3 = Misfire

4 = Emission control

5 = Vehicle or Idle speed

6 = ECU or output

circuit

7 = Transmission

8 = Transmission

9 = SAE Reserved

0 = SAE Reserved

= Variable

Electrical

Fundamentals,

Sensors and Testing

• Resistance

• Voltage (DC & AC)

• Duty cycle/pulse width

• Current

• Frequency

What Testing Can We Do?

• Compression

• Fuel pressure

• Vacuum/pressure

• Back pressure

• Timing

ELECTRONIC MECHANICAL

Scanner gives direction: Fault codes & live data

The physical

pathway for current

flow is called an

electrical circuit

Electrical Fundamentals

Voltage

• Voltage is an electrical force or pressure, which causes current to flow through an electrical conductor:

• Measured in units of volts (V)


Current

• Current is the flow of electrons through a conductor

• Measured in units of amperes or "amps" (A)


Resistance

• Resistance is the opposition offered to the flow of an electrical current by a substance through which it is passing

• Measured in units of ohms ()

• Symbol for calculations is (R)


• Resistance testing requires the component to be taken out of circuit

• Resistance varies with temperature

• Resistance testing is not “live testing” in a normal operating environment

Resistance Is Futile!

• Resistance has limited use

• Use volt drop

• Use current

How Do We Test Circuits?

V

A

Current with a constant voltage = Higher resistance - lower amps Lower resistance - higher amps

Ohms Law

• A relationship exists between the

voltage, current and resistance within

the circuit, and this relationship is

called Ohms Law

• Ohms law states:

– “That one Volt is required to pass one Amp through a one Ohm resistance, providing that the temperature remains constant”

• An easy way to calculate Ohms law,

within a circuit, is to use the diagram

to the side

V

A R X

Example

• A heated rear screen has a resistance of 0.5 Ohms

• Using Ohms Law, calculate the total current flow within the circuit, assuming a battery voltage of 12V

V

A R

?

12 Volts 0.5 Ohms = 24 Amps

Watts Law

• When electricity flows in a circuit, the electrical energy is converted into thermal energy (heat), radiant energy (light) or mechanical energy (movement)

• The amount of work done by electricity in a time unit (i.e. one second) is called electrical power

• This is measured in Watts (W)

V

A R

W

A V X

Voltage

12v BATTERY

12v

Voltage

12v BATTERY

<0.5v

Voltage

12v BATTERY

12v

Bad Earth

0.5v

Volt Drop Testing

LOW RESISTANCE

More voltage gets

through the circuit

RESISTANCE

3.4v

HIGH RESISTANCE

More voltage gets

through the meter

(Path of least

resistance)

Volt Drop Positive

ECU

BATTERY

0.5v

Volt Drop Negative

ECU

BATTERY

0.5v

Voltage ECM Output

SENSOR ECU

BATTERY

0.25 TO 4.75V

Note: If 5v NO circuit exists

SENSOR ECU

BATTERY

Typical sensor cicuit

+ve

Measuring Point

Inside ECU

SENSOR ECU

BATTERY

Typical Sensor Circuit

+ve

0.2 v 0.2 v

0.2 v ECU measures

voltage here

TEMP SENSOR

SIGNAL

PCM

1.5 volts FAULT CODE

CTS VOLTAGE

HIGH

0 volts 5 volts

1- 4 v +ve

Current can tell us:

• There is a circuit…current can only flow if there is a circuit

• How much current is flowing

• What work is being done by the component

Current ramping is an advanced technique used with oscilloscopes

Current Testing

• Analogue (AC wave form output)

• Digital (square wave form output)

• Frequency

• Pulse width (Modulated)

• Duty cycle (Modulated)

Jargon Busting

The ECM uses all of these signals to control and monitor

sensors and actuators

Analogue Waveform

Digital Waveform

Digital Square Waveform

Frequency

1 sec

period

Voltage does not change due to frequency increase

Voltage must peak to input voltage and switch to 0v for ECU to acknowledge an

on/ off signal

On time

Off time Total time, one cycle = 100%

Variable Pulse Width (PWM)

Duty Cycle 30%

• Pulse width alters the current being used.

• Pulse widths can be measured with duty cycle.

PWM & Duty Cycle

Current

Pulse

Inputs Outputs

Basic System Layout

Fuel Pump

What tests can I do Failure effects Different

types

What is it used for

Current

Volt drop

Pressure

Actuator tests

(Scanner)

Non start

Incorrect

fuelling

Surging

Misleading

DTCs

No Proving sufficient flow and

pressure to the fuel rail

Fuel Pump Analysis

Any motor can be tested for current flow. The waveform can tell us a great deal about the circuit.

Fuel Pump Analysis

Find a convenient point in the circuit and simply

clamp one of the wires.

Inbuilt Tuition

Fuel Pump Testing

Fuel pump speed analysis

Dead segments in pump

Fuel Pump Testing

Inputs Outputs

Basic System Layout

Ignition Coil

What tests can I do Failure effects Different types What is it used for

Primary voltage

Secondary voltage

(kv)

Resistance

Primary current

Non start

Misfire

MIL

Wasted spark

Direct

Distributor less

To send sufficient

voltage to the

spark plug to ignite

the fuel air mixture

at the right time

What tests?

Coil Principles

The ignition coil is a step-up transformer that converts supply voltage to the high voltage required to jump across a spark plug gap.

+ 12v

Switched Earth

HT

Conventional System

Terminal 15

Ignition Supply

Terminal 1

Coil Control

ECU/ Ignition AMP

Removing the points and

condenser

Primary

Secondary

Direct connection to

plug COP System

1342

Firing

Order

TDC

Power

TDC

Exhaust

Double Ended Coil

System

Common

Supply

1342

Firing

Order

Double Ended Coil

System

TDC

Power

TDC

Exhaust

There are a few combinations of coil but all

operate in exactly the same way as each

other.

Coil Pack, Cartridge and Coil On Plug.

Ignition Coils

Ionization

• Detection of an engine misfire can take between 20 and 90 seconds for the ECM to detect and respond

• Possible damage to the catalyst if a prolonged misfire occurs

• The misfire may also be caused by an injector or an air leak on a manifold

• By using an ionization trace a misfire can be detected immediately

• This is done by an additional amplifier built into the coil pack which puts a small voltage to the spark plug which in normal circumstances would not earth out to the electrode. High tension voltage creates the ionization field which is plasma, when combustion has taken place then the voltage will track across the ion particles in the plasma field and discharges to earth, the ECM now knows that combustion has taken place.

• This very accurate control and the ECM can use this trace for cylinder recognition so the ECM does not require a cam sensor signal

• Also because the ionization can accurately detect the combustion gas quality, it can detect pre detonation as well

Low volt

Ion circuit

12v Theoretical diagram only

Voltage stored in the low volt ion circuit discharges when ion particles are present (combustion)

Coil On Plug Adapter

Built-in Tuition Guidance

Ignition Coil Signal

Inputs Outputs

Basic System Layout

Fuel Injectors


Duty cycle

Pulse width

Current

Fuel pressure drop

Actuator test

(scanner)

Non start

Black smoke

Misfire

Poor performance

Mechanical

- Ve switch

+ Ve switch

Injects the right

amount of fuel Into

the engine

Fuel Injector

Why do we need it?

• The fuel injector supplies fuel to the engine when switched by the ECU.

• Can be located in the inlet manifold (MPI) or in the cylinder head (DI)

What happens if it fails?

• Misfire/hesitation

• Lean/rich mixture

• No start/cutting out

• Noid lights do not tell if injector has fired

• Current

• Pressure drop (with scanner)

• ASNU

• Exhaust gas analysis

Testing Injectors


Fuel Injector Current Ramp

Battery voltage due to no ground being supplied by ECU

No ground means no current is flowing as injector is not energised

ECU Provides ground to injector

The injector is now energised, meaning current flows into the injector windings

The windings reached their saturation point. Enough energy is stored to

overcome pintle spring & fuel pressure

Current ramping is still present as injector needs it to remain open against spring & fuel pressure The ECU removes the ground supply, this

causes the magnetic field which has built up in the windings to be released. This is

known as Electro-Motive Force

(EMF)

This deflection in the voltage on the falling edge is where a diode in the ecu is regulating the rate current diminishes from the circuit. Preventing

pintle bounce and seat damage.

Injector Voltage (Request)

Injector (Amps)

Good waveform Bad waveform

Piezo Injector Driver Signal

Piezo Injector Amps Trace

Inputs Outputs

Basic System Layout

Crankshaft Sensor

What tests can I do Failure effects Different types What is it used for?

AC voltage

Resistance

Oscilloscope

Scanner

(engine speed)

Non start

Misfire

Hall effect

Ac generator

Magnetic

Engine speed

TDC reverence

Misfire detection

What is it used for?

CKP Crank Position Sensor

Crankshaft position sensor (what's it for)

• Engine position (ref cylinder 1 TDC)

• Engine speed

• Used for misfire detection

• Accurate engine timing in conjunction with cam sensor

Live Data, CKP


CKP Crank Position Sensor

Crankshaft position sensor

Permanent magnet sensor (generator)

Crank sensor output (Waveform)

The speed of crankshaft rotation affects the size and shape of the waveform

0v

Onboard Misfire Detection

…the crank slows for compression

and accelerates on power…

Slow Fast


…so when a misfire occurs

the crank does not accelerate as expected…

Slow Fast Slow Fast Slow Slow Fast

Misfire Event


Case Study

Outputs

Basic System Layout

Inputs

Cam Position Sensor

What tests can I do Failure effects Different types What is it used for?

AC volts

Resistance

(inductive only)

DC volts

Oscilloscope

Non start

Misfire

Hall effect

Frequency

Inductive (AC)

Cylinder reference

Misfire detection

Engine position

Hall Effect Sensor

Magnet

Plate

Digital Cam Sensor Testing

Analogue CMP Sensor Testing


Inputs Outputs

Basic System Layout

Manifold Pressure Sensor


Volts

Frequency

Vacuum

No idle

Erratic Idle

Poor performance

Black smoke

Analogue

Digital

Sense engine load

Turbo control


Map Sensor Signal

Inputs Outputs

Basic System Layout

• Coolant temp sensor (why is it needed?)

• Identifies cold and hot engines

• Cold start enrichment

• Hot soak starting

• Emissions control

Faulty component will cause:

• Possible not start

• Poor running

• High fuel consumption

• High emissions

• Misleading fault codes

Coolant Temp Sensor

Outputs

Basic System Layout

Inputs

Throttle Position Sensor


Voltage

Frequency

Scanner

MIL on?

Analogue

Digital

Acceleration enrichment

Over-run fuel cut off

Auto box kick-down

5v +

0v -

Signal Return

0.25V 4.5V

TPS Sensor

TPS

TPS

TPS Signals

Outputs

Basic System Layout

Inputs

Mass Air Flow Meter


Output Volts

Volt drop

Frequency

Loss of power

Analogue

Digital

EGR control

Fuel quantity control

Turbo control

(MASS, MAF, AMM)

Live Data, AMM

What’s The Difference?

Diesel Petrol


Digital AMM

MAF Sensor Testing

Digital sensors give a square waveform which can be checked with an oscilloscope

This is a variable frequency signal that can be measured with a graphing meter

Outputs

Basic System Layout

Inputs

• To keep the catalytic converter happy the ECU controls fuelling (air fuel ratio)

• Fuelling can be altered to compensate for wear/ageing and other fuelling problems

• Correct fuelling is achieved by the ECU altering the injector on time

Closed Loop Control

Heater Oxygen Sensor

What tests can

I do

Failure

effects

Different types What is it used for

Voltage

Current

Frequency

Incorrect

fuelling

Surging at

cruise

Zirconia

Titania

Wideband

Fuel control

Catalytic converter testing

B1S1, Pre catalytic converter

B1S2, Post catalytic converter


By increasing and reducing the Injector Pulse Width, the PCM can satisfy two important functions:

1. Send measurements to the PCM so that it can maintain the A/F at a desired 14.7:1 ratio (stoichiometric)

2. Maintain an efficient Catalytic Converter.

O2 Sensor Closed Loop

Zirconia Sensor

1 Hertz

Outputs

Basic System Layout

Inputs

Pre Cat Sensor

Upstream

Post Cat Sensor

Downstream

Post Cat Oxygen Sensor

Knock Sensor


Oscilloscope

Volt drop

Loss of power

Analogue Combustion cylinder

knock

Knock Sensor Construction

1) Retaining bolt

2) Engine cylinder block

3) Electrical connections

4) Seismic mass

5) Piezoelectric element

Body

Piezoelectric Crystal

Seismic Mass

Knock Sensor

Knock Sensor


QUICK BREAK

Live VERUS Pro Demo

MODERN DAY DIAGNOSTICS

What is the key to profitable

vehicle diagnostics?

MODERN DAY DIAGNOSTICS

What is the key to profitable vehicle

diagnostics?

Can we still apply the same “tried and

true” diagnostics methods from before?

IT’S ALL ABOUT SPEED AND

EFFICIENCY!

Average diagnostic charge is £20 per hook up

Average charge per healthcheck is £10

The more you do the more money you

make

%

%

%

%

IT’S ALL ABOUT SPEED AND

EFFICIENCY!

Diagnostic Time

Diagnostic Tool Return on Investment

Input in blue coloured cells:

How long will you, or have you had your tool? 24 Mth

How many times do you hook up per week? 5

What is your diagnostic charge? £25

How many Health Checks per week? 5

What is your Health Check charge? £25

Total you have spent on subscription? £1889.76

How much did you pay for your tool ? £2911.92

Income generated since you bought the tool £26,000

Total Profit for the 24 Months £21,198

RETURN ON INVESTMENT


VERUS PRO BENEFITS

1. JOB CARD: A permanent time, dated recorded history of the vehicle (with

DTCs and additional notes or attachments)

2. KNOWN GOOD VALUES: History of scope comparisons

3. COMPONENT TEST METER: Shows you where and how to connect, tells

you what the results should be and the possible causes

4. INFORMATION: Component locations and wiring diagrams

5. INTERNET ENABLED: For diagnostic forums and information


We hope tonight’s presentation has been of interest to you, and that we have been able to answer some of those questions you

always wanted to ask.

Thank You

Documents

Administration - Snap-on • Fire procedure • Toilets ... This deflection in the voltage on the falling edge ... The speed of crankshaft rotation affects the