Electronic Ignition systems

Advantages of EIo Fewer moving parts – no distributoro Flexibility in mounting locationo Less required maintenanceo Reduced radio frequency interferenceo Elimination of mechanical timing adjustmentso No mechanic al load on engineo Improved coil saturation time

1st generation of EI used coil packs of 2-4 coils Waste spark= uses a single coil in a multiple coil pack to fire two cylinders at one time Increased primary on-time & coil saturation One coil for each two cylinders – (6 cylinder = 3 packs, 4 cylinder = 2 pack) ect. Fires two cylinders at a time Crank / cam sensor for primary switch and timing input Base timing permanently set. Module usually part of the coil pack PCM controlled

Waste – spark basic components

DIS = distributor less ignition system Coil pack Module Spark plug wires Spark plugs Crankshaft or camshaft position sensor PCM and harness

Component locations

One of the huge advantages is that the coil packs can be mounted virtually anywhere some good some bad

Top of the engine Lower back side transverse engine

Types of coil packs

Type 1 coil pack is all one piece If one coil fails – all have to be replaced Uses crank sensor for input Module is lower half and removable type 2 coil pack all coils are mounted separate If one coil fails, they are replaceable individually. Uses both crank and cam sensors instead of distributor

Coil packs

Some have coil packs that all the coils and module are one piece and replace as a unit. Others there is no module, the module function has been taken over by the PCM

Crank pick-up

Crank/cam signal can be analog – pick up coil Can be digital – hall effect Sensors can be external on the front of crank balancer Can be internal on the crank through the oil pan

Primary circuit operation

Magnetic PM crankshaft position sensors (analog)o this sensor uses the changing strength of the magnetic field surrounding a coil or wire to

signal the module and computero this signal is used by the module and computer as to piston position and engine speed

to switch the primary coil on and off Hall effect switch

o This switch uses a stationary sensor and rotating trigger wheel (shutter)o Produces a digital signalo This signal is used by the module and computer as to piston position and engine speed

to switch the primary coil on and off

Module

Remember the crank/cam sensor is the primary signal(pulse) The module is the switch If module or crank sensor is defective – no pulse Module located beneath coil packs

Operation

Waste spark ignition systems fire two spark plugs at the same time. Each coil is a true transformer in which the primary windings and secondary windings are not

electrically connected Each end of the secondary winding is connected to a cylinder exactly opposite the other in the

firing order, which is called a paired cylinder Waste spark ignition system

o This means that both spark plugs fire at the same timeo When one cylinder (for example. 6) is on the compression stroke, the paired cylinder (3)

is on the exhaust strokeo This spark that occurs on the exhaust stroke is called the waste spark, because it does

no useful work and is only used as a grounded path for the secondary windings of the ignition coil

o They are in series! One spark plug of each pair fires straight polarity and the other cylinder fires reverse polarity 1 compression stroke 1 exhaust stroke Series circuit

Waste spark ignition systems

Each spark plug for a particular cylinder will always be fired either with straight or reversed polarity, depending on its location in the engine and how the coils are wired

However, the compression and waste spark condition flip-flops When one cylinder is on compression, such as cylinder number 1, then the paired cylinder

(number 4) is on the exhaust stroke The voltage required to jump the spark plug gap on a cylinder 4, the exhaust stroke, is only 2 to

3 KV and provides the ground circuit for the secondary coil circuit The remaining coil energy is used by the cylinder on the compression stroke, 10-12 KV On spark plug of each pair fires straight polarity and the other cylinder fires reverse polarity Odd number cylinders fire straight polarity

Circuit operation

Ignition positive to coil primary PIP crank signal to PCM Spout out to coils – pulses primary Induction to secondary coil Fires both plugs Ignition 12 v to module and coil positive – note: also to injectors Crank sensor to module and PCM Crank signal fires both the coils and injectors sequentially.

EI or COP systems have:o Fewer moving parts – no distributoro Flexibility in mounting locationo Less required maintenanceo Reduced radio frequency interferenceo Elimination of mechanical timing adjustmentso No mechanical load on engineo Improved coil saturation time

What makes COP better then waste-spark? Coil on plug (COP) ignition uses one ignition coil for each spark plug This system also has similar system called coil by plug. Coil near plug, or coil over plug ignition We have eliminated the more expensive coil pack and module Eliminated the spark plug wires Reduced maintenance Components are individual for control and monitoring Misfire monitor

Components of the COP system PCM Coil Spark plug Some – plug wire & module

Direct ignition Early GM version (IDI – Integrated direct ignition) of coil over plug Coils and module are all one piece Flat wire internal for secondary voltage to plugs.

Coil near plug Still has plug wires Coils mounted near plugs Individual coils Current system

COP ignition

There are two basic types of coil on plug ignition including : 2 wire This design uses the vehicle computer to control the firing of the ignition coil The two wires include ignition voltage feed and the pulse ground wire, which is controlled by

the computer All ignition timing and dwell control are handled by the computer No separate module

Two wire circuit Two wire circuit Battery positive Pulse from the PCM Input from the crank & cam sensor

3 wire COP This design includes an ignition module at each coil Module pulse (fires) the coil with a signal from the PCM The three wire include:

o Ignition voltageo Groundo PCM signal

3 wire COP circuit Three wire circuit Positive battery from ignition switch Signal from PCM to module Ground Module in each coil

Crank/Cam sensor Our signal to the coil comes from the crank, or crank and cam sensors Signal to PCM Signal from PCM to coil if a 2 wire

Ignition system components and operation Ignition control (IC) is the OBD-II terminology for the output signal from the PCM to the ignition

system that controls engine timing Ford referred to this signal as spark output (spout) and general motors referred to this signal as

electronic spark timing (EST) This signal is now referred to as the ignition control signal (IC) The ignition control signal is usually a digital output that is sent to the ignition system as a timing

signal If the ignition system is equipped with an ignition module, then this signal is used by the ignition

module to vary the timing as engine speed and load If the PCM directly controls the coil, such as most coils on plug ignition systems, then this IC

signal directly controls the coil primary and there is a separate IC signal for each ignition coil. Each coil is controlled by the PCM, which can vary the ignition timing separately for each

cylinder based on signals the PCM receives from the knock sensor(s) If the knock sensor detects that a spark knock has occurred after firing cylinder 3, then the PCM

will continue to monitor cylinder 3 and retard timing on just this one cylinder if necessary to prevent engine damaging detonation

Ion sensing ignition In an ion sensing ignition system, the spark plug itself becomes a sensor

The ignition control (IC) module applies a voltage of about 100 to 400 volts DC across the spark plug gap, after the ignition to sense the plasma inside the cylinder. (resistance)

The combustion flame is ionized and will conduct some electricity, which can be accurately measured at the spark plug gap.

The coil discharge voltage (10-15 KV) is electrically isolated from the ion sensing circuit The purpose of this circuit includes:

o Misfire detection (required by OBD-II regulations)o Knock detection (eliminates the need for a knock sensor)o Ignition timing control (to achieve the best spark timing for maximum power with the

lowest exhaust emissions)o Exhaust gas recirculation (EGR) controlo Air-fuel ratio control on an individual cylinder basis

Ion sensing ignition systems still function the same as conventional coil on plug designs, but the engine does not need to be equipped with a camshaft position sensor for misfire detection, or a knock sensor because both of these faults are achieved using the electronics inside the ignition control circuits

Triggering System

Purpose Both use a triggering system What is the purpose of the engine triggering system? Open and close the primary ignition system to activate the secondary ignition and fire the spark

plugs Time the firing of each of the individual spark plugs Control the timing advance

System types Systems with only a single crank sensor EI systems with cam sensor in the distributor opening EI systems with cam sensor in timing cover Systems with crank and cam sensors Systems with dual crankshaft sensor Slower start systems – 2 revolutions of crankshaft Fast-start EI systems – ½ turn of the crankshaft for start-up

Basic operation When the PCM receives a digital signal (hall-effect) or an analog signal (PM generator) on

information of crankshaft rotation, speed, and placement – we can use this to sync and control timing and firing of the spark plugs and fuel injectors

Multiple on-off signals

Ford EI Crank sensor inside timing cover

35 tooth reluctor – 1 tooth missing Tooth every 10 degrees Sequences on missing tooth Crank sensor then can provide input on crank position and speed. (firing and timing)

Specific manufactures systems GM 2.8, 3.1, 3.4 v-6 engines PM generator and reluctor in crank

Basic operation This system uses a pick up coil type PM generator and a notched reluctor ring cast into the

crankshaft inside the oil pan Six notches spaced 60 deg. Apart 7th notch 10 degrees from 6th

7th notch is the sync Counts 1 Fires coil 2-3 on second notch Counts 3 & 4 Fires coil 1-4 on notch 5 Counts 6 Syncs on 7 Starts over

Ford EEC –IV Crank PIP hall effect sensor on front pulley Crank PIP monitors crank position and speed. 3 slots = 3 fire = 6 cylinders. PIP signal on-off (but not synced to any cyl) PIP to PCM-out to module (spout) Spout reference pulses coil Cam hall-effect sensor in distributor Cam – CID (cylinder identification) syncs Spout reference pulses coil

GM Located on front crank pulley No cam sensor Double hall effect Outer ring is sync – once per crank rotation. 1 slot Inner ring has 3 slots or equally spaced blades 60 degrees apart & blades 60 degrees long (6 cylinder) The leading edge inner crank sensor signal is therefore received every 120 degrees Each time a leading edge signal occurs – the coil primary opens and fires a pair of spark plugs Waste spark

Daimler Chrysler EI PM sensor on flywheel 4 slots per coil – 12 total slots Slots 20 degrees apart, inputs crank position and speed for firing and timing and advance

Leading crank slots at 9, 29, 49, and 69 degrees BTDC. When engine is cranking and at idle coils will fire at 9 BTDC – the faster the crank speed the

earlier they fire Has cam sensor located in timing cover Sensor gear has 2 single slots, 2 double slots, and 1 triple slot Coils are sequenced and fired off of the input from both the crank and cam sensors When PCM counts 1 cam and 4 crank slots – fires coil 2 When PCM counts 2 cam slots and next 4 cranks – fires coil 3 When PCM counts 3 cam slots and next 4 cranks – fires coil 1 Advances timing of spark on crank speed at sensor

Fast start – EI Has cam sensor – sequences injectors – not coils Dual crank sensor Inner ring has 3 blades of unequal lengths and spacing – 3x signal Spaces between blades are 10, 20, & 30 degrees long Outer ring has 18 blades of equal length and spacing – called 18x signal Leading edge of the 3x are spaced 120 degrees apart and fires coils 75 degrees after this signal. The 18x leading edge signal is every 20 degrees or 18 times in one crank revolution So the module/PCM monitors the 18x in relation to the 3x signal In the 10 degree window one trailing edge signal is received In the 20 degree window two signals are received In the 30 degree window three signals are received

Basic checks Confirm the complaint – test drive Visual checks – wires, connectors, damage “the big 4” Spark, fuel, timing, and compression Check vacuum Scan for codes and misfire What kind of symptoms with EI problems? Separate to pinpoint area test

EI diagnosis If we have a misfire were do we start or concentrate our pin point test? Individual systems – coil, wires, plugs. Misfire is not normally common to all cylinders If we have a no start where do we concentrate our pinpoint test? Primary ignition – power, module, crank/cam sensor, PCM. Failure in primary would most likely

effect all cylinders

No start Typical causes of a no-spark (intermittent spark) condition include the following:

o Weak / defective ignition coilso Low or no voltage to the primary (positive) side of the coilo Negative side of the coil not being pulsed by the ignition moduleo Defective crank/cam sensor

o Defective moduleo Wiring, PCMo There are a finite number of possible causes

Checking for spark Remove the plug wire from the distributor cap or spark plug, install a spark tester, and crank the

engine A good coil and ignition system should produce a blue spark at the spark tester Test at plug or coil

No start – EI/COP COP – 12 volts to coil with key on Test light to the negative side of the coil and crank the engine. – should blink Indicating that the primary coil current is being turned on and off Remember most injectors get pulsed from the same signal – if easier check at or confirm at

injectors If when you crank the engine – ignition on – 12 volts at the positive coil and you have no pulse

or reference signal: What could be the problem? Crank / cam sensor – signal Module – switch PCM – switch Connections / wiring Confirm on scanner – RPM = signal No – check the crank / cam sensors Visual –damage - wires – connectors Gap or clearance – feeler gauge Resistance – check specs - ohm meter Pulse – DVOM Waveform – genesis – lab scope PM sensors must be magnetic If the permanent magnet inside the sensor has cracked, the result is two weak magnets Use paper clip or other metal to test magnetic The sensor can be tested using a digital meter set to read AC volts. 0-1 volt minimum Should fluctuate back and forth If no signal from the sensor, no scanner RPM, or resistance check fails Replace the sensor If you have a good signal from the crank and cam sensor, no signal at the coil, voltage to the

coil, and no spark, where do you go now? PCM

No spark EI – Coil packs Where do we start on a coil pack system with no spark? It could be a bad coil, but if it’s common to multiple coils? We need to check for positive volts and reference Check for RPM on scanner when cranking – RPM comes from crank / cam sensor just like

reference signal. If no RPM and reference signal? Check crank / cam sensor

No spark EI – Waste spark Confirm on scanner – RPM signal No – check the crank / cam sensor Visual – damage wires connections Gap or clearance – feeler gauge Resistance – check specs – OHM meter Pulse – DVOM

Coil pack – NO spark If sensors are ok, remove coils from module and test Test for battery voltage at pin 1 with key on. No voltage ignition switch, fuse, wiring If voltage – test for reference pulse Test across pins 1 and 2 – should pulse with crank (positive and switching ground) If you have a good signal from the crank and cam sensor, no signal from the module at the coil,

voltage to the coil, and no spark, where do you go now? Check if signal to the module If to the module, but not out of the module to the coil? Module! If not to the module? PCM!

Misfire or no start with pulse? Positive voltage, crank/ cam sensor and module are ok Could be coil, plug wire, plugs, or cylinders Could also be timing, or fuel delivery Check for spark at plugs Check for all components for excessive resistance, corrosion, wear, and check compression

Power control module (PCM) Take inputs Stores information Compares to files Send output Store memory of outputs and faults Can be programmed Doesn’t think or calculate Same input and same output every time

Communication

Computer communicates by voltage signals 5 volt & 12 volt inputs 12 volt – most outputs Most outputs are Digital Most inputs are analog

The four basic computer functions The operation of every computer can be divided into four basic functions

o Input o Each sensor transmits its information in the form of voltage signals.o Storage o Files of memory, information and tables to compare to inputs coming ino Processing o Compared to stored information and changed into output voltage signals or commandso Outputs o Commands or sends voltage signals out to a switch or solenoid to operate a system

Inputs Sensors Voltage signals in: TPS ECT CKS EGO MAF Most 5 volts 3 wires called? Potentiometer

Potentiometer Most commonly used input sensor is a potentiometer 3 wire connection – voltage , ground , signal Input 5 volts from the computer Ground Middle wire, signal – a portion of the input based on the contact point of the wiper

Rom – Prom Read only memory, can read only Permanent memory – stays even when car is off or battery disconnected Engine and transmission type/size/equipment Look up tables Prom Programmable read only memory The specifications of a particular car EPROM

RAM Random access memory

Volatile ram Temporary written memory – scratchpad Driving conditions Erased with key off

KAM keep alive memory also ram, but non – volatile temporary but stays with key off codes, adaptive re learn can be erased by scanner or battery disconnect decisions or problems made while operating

Outputs an output is any electronically controlled device that can be turned off or on purge solenoid EGR Idle speed control Coil spark - IC Fuel injector Motors Actuators Switches Relays Solenoids

Outputs = grounds Outputs/actuators are turned on by completing ground or 12v Fuel injectors are outputs – receive 12V – computer grounds Providing ground to the windings of the cooling fan relay

Duty cycle Outputs to actuators are turned on & off in different ways Duty cycle is percent of on – time 10%, 62%, 18%, ect … 1 total cycle is always a constant/same time

Pulse width Pulse width is duration of on-time Pulse time is variable Could be 1 ms to 1 hour (theoretically) Not a percent of time, but length of time Measured in milliseconds

Open loop Engine is cold – coolant temp below 140F

Oxygen sensor is below 600F – light off During normal warm up Pre programmed rich mode Definition: engine is an open loop – not receiving information from sensors Will also go or stay in open loop if there are computer faults or certain codes

Closed loop Engine is warm Coolant temp is above 140F O2 sensor temperature is about 600F and PCM uses its electrical signal to control

OBDII introduction and implantation OBD II- designed to detect engine, system wear, or a component malfunction causing an

increase exhaust emissions by 50% Specific monitoring and protecting of the catalytic converter are major priorities of the OBD II

system. OBD II- 1994 -1996 phase in period in response to federal emission control monitoring standards Universal data link connector (DLC) Standardized location for DLC Standard diagnostic trouble code (DTC) Common scan tool usage Scan tool must be able to erase trouble codes Standardize terms for electronic control systems Store codes that affect emissions and record snapshots

Malfunction indicator lamp operation Diagnostic trouble codes (DTC’S) – five digit alpha – numeric code Read on scanner 1st digit – the system were the code was set

o B- bodyo C – chassiso P – power traino U-undefined

2nd digit – OBD II mandated or MFG’s codeo 0 – SAEo 1 – manufacture

3rd digit – is the area or sub group,o 1 – fuel / air system

o 2 – fuel / airo 3 – ignition systemo 4 – emissionso 5 – idle speedo 6 – PCM

4th and 5th digit – specific areas were the trouble code is.