Permanent magnet (PM) generator: Uses principle of induction to develop AC signal Signal sent to either ICM or PCM Signal converted to on/off reference signal, used as base triggering for primary circuit Crankshaft position sensor: Must have .050" (± .020") air gap between sensor and reluctor EI system (electronic ignition): Sensor mounted in block or front cover Non-adjustable DI system (distributor ignition): Pickup coil operates similarly Magnetic field increases and decreases as teeth of timer core and pole piece move in and out of alignment Induces AC flow through pickup coil, as triggering signal to ICM EI system: Uses PM generator and reluctor Crankshaft reluctors on most four and six-cylinder engines have seven notches: Six notches equally spaced at 60° intervals Seventh or "Sync" notch synchronizes coil firing sequence with crankshaft position On four-cylinder engines, ignition module recognizes sync notch Note — Coil pack for 2nd cylinder in the firing order always fires first during start-up. On 60° V6 engines, the module: Skips notch 1 after sync signal Fires 2-5 cylinders on signal from notch 2 Skips notch 3 Notch 4 fires 3-6 pair Notch 6 fires 1-4 pair PM generator output: Voltage varies with engine speed Values range from approximately 500 millivolts to 100 volts When measuring output from magnetic crank sensor, set voltmeter on appropriate AC scale Varies based upon cranking speed, air gap of the sensor to the reluctor, resistance of the windings, temperature of the sensor, and strength of the magnet. Pull-up/pull-down hall switching: Power source is outside PCM in "pull-up" circuit Switch closed - external source voltage provides high reference signal to PCM Switch open - low reference signal provided Pull-up/pull-down hall switching (continued): "Pull-down" circuit is provided reference voltage signal from PCM Power source internal to PCM Switch closed - source voltage pulled low to external ground and PCM registers low voltage reference signal Switch open - PCM registers high reference signal The Hall effect: when a magnetic field is introduced perpendicular to a current flowing through a semiconductor, a measurable voltage is induced at the sides of the semiconductor; at right angles to the main current flow. The Hall effect switch: Produces voltage signal controlled by presence or absence of magnetic field in electronic circuit Regulated signal voltage from ignition module is passed through semiconductor wafer in Hall switch Permanent magnet mounted beside semiconductor induces Hall voltage across semiconductor Crank sensor positioned so "vanes" pass between semiconductor and permanent magnet Magnetic field interrupted when metal vane comes between magnet and semiconductor Hall voltage drops off Hall voltage amplified and routed to transistor, which controls ground on signal voltage from ignition module Vane outside sensor, transistor is ON and signal from module is grounded when full voltage present Vane inside sensor, transistor turns OFF and signal returns to high state when voltage drops Signal voltage alternates between high and low states, generating square-wave pattern as interrupter rotates Opti-spark: Optical pick-up first used in 1992 Provides actual crankshaft position, in degrees, to PCM Uses flat disk with two rows of notches cut around its circumference One row has 360 notches, each 1 degree wide One row has eight notches, arranged in staggered pattern Optical sensor uses infrared light source and receiver Optical pick-up produces two digital signals 360 notches produce high resolution signal used to fine tune engine's timing , especially at higher RPM Eight notches produce low resolution signal used for RPM reference No low resolution signal, no spark or fuel delivery Engine will start and run without high resolution signal, but long crank complaint, along with reduced performance, could be noticed Opti-spark system components: Distributor housing Cap and rotor Optical position sensor Sensor disc Pick-up assembly Distributor drive shaft Magneto-resistive (MR) sensor is similar to Hall effect switch: Requires magnetic field to operate Has three wires Produces digital output signal Magneto-resistive (MR) sensor: Permanent magnet positioned between two magnetic reluctance pick ups, MR1 and MR2 Magnetic field changes in area of MR1 and MR2 as reluctor wheel passes MR1 and MR2 produce identical voltage signals, but MR2 signal is later Imperfections can cause excessive crankshaft position sensor noise and may cause improper operation of on-board diagnostics Magneto-resistive (MR) sensor (continued): MR1 and MR2 signals cause differential amplifier to produce MR differential output Signal used to switch Schmidt Trigger ON and OFF VCM does not supply pulled-up signal wire MR sensor pulls signal up to 5-volts and toggles it to ground Secondary: Carries up to 100,000 volts Consists of ignition coils, plug wires, and spark plugs DI system also has distributor cap and rotor Coil: Major component of secondary circuit Greatly increases secondary voltage Designed to take 12-14 volts and step it up Part of both primary and secondary Coil output affected by: Amount of current flowing through primary winding Number of turns of wire on secondary side Diameter of wire Factors limiting ignition coil output: Step-up in voltage results in proportional decrease in amperage When primary winding current low, current on secondary side may be significantly lower With excessive secondary resistance, insufficient energy to jump spark plug gap Spark plugs: Secondary voltage arcs across air gap and ignites air/fuel mixture Consist of terminal post, ceramic insulator, and pair of electrodes Resistor reduces current in secondary system Electrodes subjected to extreme heat, pressure, corrosion Arcing deteriorates electrodes Fouling causes misfires Wetting can short out electrodes Cracked insulators, carbon tracking, burned electrodes, and improper torque cause poor performance Extended life spark plug: Nickel plated shell (resists corrosion) Copper core center electrode (resists carbon fouling) Platinum tips on electrode (resists spark erosion) High efficiency spark plug: Fine wire platinum electrodes, resistive to wear Nickel plated shell for corrosion resistance Ribless insulator design to provide better seal with secondary boot Wider gap than conventional plugs enhance burn characteristics Iridium to further promote longevity and corrosion resistance High energy ignition (HEI) system: Extended spark plug life Fewer moving parts reduces service Fires EGR diluted mixtures Signal for ignition timing controlled by PCM Coil primary circuit controlled electronically by solid-state components Spark plug wires: Carry secondary voltage to spark plugs Silicone rubber with fiber core: Acts as resistor, reducing secondary current Cuts down on radio and television interference (TVRS) Reduces spark plug wear Insulated boots: Strengthen plug connections Keep out dirt and moisture Prevent voltage loss Spark plug wires (continued): Resistance less than 10,000 ohms per foot High resistance causes misfire and coil damage Can be damaged if not carefully removed Never puncture plug wire or its boot to test the ignition system Electronic ignition (EI) system: Replaces DI system Eliminates many mechanical parts Components: Ignition module Ignition coils Crankshaft sensor Camshaft sensor, in some applications Interrupter or reluctor Few moving parts Remote mounting capability Increased available coil saturation time (dwell time) More coil cool down between firing events Up-integrated ignition system: Timing controlled by PCM: Triggering signal is direct input to PCM ICM turns coils ON and OFF Main functions of ICM: Turn coils ON and OFF based on signals from PCM Limit primary current flow (in some applications) Bypass systems: ICM processes triggering device signal ICM must sometimes convert signal ICM provides reference signal to PCM Primary coil current control circuits: One (DI) Two (EI, 4-cylinder) Three (EI, 6-cylinder) Four (EI, 8-cylinder) Circuits complete ground path Bypass mode: Two modes of operation: Bypass mode uses ICM controlled timing, normally used when engine is cranking, running below a certain RPM, or during default mode IC mode - the PCM controls timing IC timing: At run threshold, PCM applies signal to ICM bypass circuit Signal switches off bypass circuit and switches on IC circuit Spark timing then controlled by PCM based on inputs from MAP or MAF, Baro, ECT sensor, TPS, and reference signal Electronic ignition system types: Computer controlled coil ignition (C3I) Direct ignition system (DIS) Integrated direct ignition (IDI) Up-integrated direct ignition (UIDI) Coil per plug (CPP) Coil near plug Type determined by vehicle application Computer controlled coil ignition (C3I): Used on 3.0L/3300 and 3.8L/3800 V6 engines Has Hall effect switches for crank and cam position Interrupter ring mounted on harmonic balancer Direct ignition system (DIS) components: Two CKP sensors CMP sensor Four separate ignition coils Ignition module Eight spark plug wires and conduits Knock sensor Integrated direct ignition (IDI): Used exclusively on 2.3/2.4L SOHC/DOHC engines Uses magnetic crank sensor and reluctor on crankshaft Module, coils, and spark plugs are contained in one assembly Lower secondary resistance Check service information to ensure correct part is used Up-integrated direct ignition (UIDI): No longer has bypass timing control in ICM Timing control is up-integrated to PCM Fewer pins on module than on past models EI system secondary operation: Spark plug attached to each end of ignition coil secondary Each coil fires plugs in two companion cylinders Cylinders reach TDC at same time TDC cylinder on compression stroke is "event" cylinder TDC cylinder on exhaust stroke is "waste" cylinder EI system secondary operation (continued): Polarities of ignition primary and secondary windings are fixed One plug fires forward - center to ground Other plug fires in reverse - ground to center Requires more energy than conventional systems Both plugs in companion cylinders fire at same time Exhaust stroke plug requires less voltage to arc Compression stroke plug uses most available voltage Coil-per-plug (CPP): Has IC driver module for each cylinder Coils/modules are fired sequentially IC circuit for each ignition coil/module All timing decisions made by PCM Very high ignition energy for plug firing No energy lost to resistance of waste spark system Important notes: No ignition coil is designed to be run with secondary unloaded High voltage produced can cause personal injury and/or system component damage Spark tester that requires 25,000 volts needed to load secondary AC Delco ST-125 Kent Moore J-26792 Less than 25,000 volt spark testers could lead to misdiagnosis CKP sensor variation learn procedure: Eliminates unwanted misfire DTCs Performed when: DTC P1336 sets PCM is replaced Engine is replaced CKP sensor is replaced Variation learn procedure: Run engine, turn it off, and turn key to run position Select and enable CKP sensor system variation learn procedure from Tech 2 Start engine Apply brake pedal firmly with transaxle in park, rapidly increase accelerator pedal until it reaches fuel cutoff Compensating values are learned when RPM decreases to idle If scan tool indicates DTC P1336, system variation is not learned Coil Cassette AssemblyPage 1 of 63PP-3pp210010 Coil-at-plug system: Individual coil used for each cylinder Coil cassette: Located in center of each cam cover Ignition module and ignition coils incorporated into cassette Coil cassette components: Three coils Module RFI spring Coil-at-plug advantages: Higher available spark energy and voltage Reduced secondary losses No loss due to "waste spark" or rotor gap More available dwell time Programmable ignition energy Crossfire eliminated Reduced radio frequency interference Ignition coil cassette assembly: Connects directly to each spark plug Use correct procedures Use spark plug boot removal tool J-43094 on 3.5L engines 4.6L engines have similar boot design, but no special tools are required Coil cassette seal: Insures water and contaminants do not enter spark plug area Do not damage seal when removing cassette Acceptable to repair small nicks and cuts with RTV Coil cassette has small spring from cassette to ground: Reduces radio frequency interference (RFI) Reduces spark return path, causing less RFI If not installed, could cause static, mostly on AM stations No drivability concerns if spring is missing Ignition module: Coils that are integral to cassette Coils not designed to be replaced independently May be removed from coil cassette Module to cassette connector: If missing or damaged, there will be drivability concern Connection made through six-way connector Circuits passing through include B+, ground, and coil drivers Coil cassette trim cover: Plastic cover on top of cassette Removed with screwdriver Refer to service information for specific applications Ignition module tester, J-43298: Essential tool for Oldsmobile 3.5L Also used with 4.6L, 4.0L, and Twin Cam 2.2L Crank Position Sensor or CKP sensor Located on left side of engine block Air gap between CKP and reluctor wheel is not adjustable Operates on Magneto-Resistive principle Two sensors within single housing CKP Sensor A CKP Sensor B Contains six terminals to provide: Power Reference low Signal circuit connections between PCM and CKP sensors A and B Crankshaft reluctors: Two different modes of decoding crankshaft position sensor pulses Angle-based decode operation uses both signals Engine operates even if one signal is lost Self-clocking system: One sensor acts as clock One sensor acts as data signal Angle-based decoding increases signal accuracy and consistency Time-based decode operation will read pulse width of one signal Time-based decoding is not as accurate during engine acceleration and deceleration Input to PCM to synchronize ignition system and fuel injectors Used in misfire detection diagnostic Operates on Magneto-Resistive principle Outputs 5V digital signal to PCM Ability to sense cam position with the "key-on," engine off Input to PCM to synchronize ignition system and fuel injectors Used in misfire detection diagnostic Operates on Magneto-Resistive principle Outputs 5V digital signal to PCM Ability to sense cam position with the "key-on," engine off Camshaft Position Sensor (CMP) CKP and CMP sensor circuits (3.5L LX5): PCM supplies 12-volts and ground path for both sensors Power and ground circuits are connected to CMP sensor Two signal circuits connect CKP sensor and PCM One signal circuit from CMP sensor provides input to PCM PCM Ignition System Management 3.5L LX5 PCM: 32U Delphi Two 80-pin connectors 4.6L LD8/L37:Siemens Two 80-pin connectors PCM Ignition System Management PCM: Located in air cleaner housing to keep PCM cleaner and cooler Refer to service information for specific application PCM Ignition System Management Premium V6 and V8 applications may use different PCMs based on body style. Operation and functionality are virtually identical. PCM Ignition System Management PCM inputs for ignition control: CMP sensor CKP sensor Knock sensor TP sensor Park/Neutral position switch MAP/MAF sensor ECT sensor IAT sensor Power steering pressure switch Traction control through EBTCM Sensing Decode Mode Sensing decode mode: Switch from use of both sensors (angle-based decoding) Use only one sensor (time-based decoding) Eliminates suspect sensor signal from PCM for that ignition cycle Test can be run only once per ignition cycle CKP Sensor Status data parameter displays ACTUAL PCM operating mode PCM’s 24x crank sensor data must read 0 before making command All DTCs must be cleared To begin decode mode test: Choose Powertrain Special Functions Engine Output Controls Crank Position Sensing Decode Mode Knock sensor: Used by PCM to detect engine knock PCM calculates average of each signal received from knock sensor Must be replaced if dropped or over torqued 4.2L ignition system: Coil-per-plug Controlled by PCM Adjusts spark timing based on sensor inputs: TP sensor ECT sensor MAF sensor Knock Sensor IAT sensor VSS Transmission Gear Position Six ignition coils CKP sensor: CKP is permanent magnet generator, known as variable reluctance sensor Magnetic field altered by slots in crankshaft reluctor wheel Seven machined slots: 6 equally spaced 60° apart Seventh used for sync pulse Signal received by PCM Coil/Driver Module Eight coil/driver module assemblies: Three different brands: Denso Melco Delphi Function the same, but not interchangeable Length of spark plug wires vary, depending on brand All timing decisions made by PCM Four-wire connector on coil/driver module "A" for ground "B" for reference low "C" for IC signal from PCM "D" is ignition feed for coil Very high secondary ignition voltage Shorter wire so less energy lost to resistance Sequential firing so no energy lost to resistance of waste spark gap Avoid body contact Melco and Denso coil characteristics: Windings cannot be measured with ohmmeter Permanent magnet is part of core Grounded internally through PCM Grounded externally through mounting bracket bolts Delphi coil characteristics: Clip dissipates any surface charge Secondary winding resistance can be measured with ohmmeter Primary winding resistance cannot be measured with ohmmeter All coil/driver module designs contain circuitry to: Keep unwanted EMI out Prevent ignition noise Eight IC circuits between PCM coil/driver modules: 0V - 5V signal Voltage is low when module is not triggered Voltage rises to 5V to begin coil dwell When module sees falling edge, it fires plug Camshaft Position Sensor Ignition timing dependent on CMP and CKP sensors Identifies cylinder stroke Information used by PCM to determine cylinder stroke Reluctor wheel: Machined as part of camshaft Interrupts magnetic field within CMP sensor Produces signal for PCM Crankshaft Position Sensor CKP sensor is critical for ignition system operation Damaged sensor could result in engine not starting Sensor to reluctor clearance is very important Sensor must not contact reluctor ring Found on right lower rear engine block, behind starter Reads reluctor wheel on crankshaft CKP reluctor wheel: 24 notches of two different widths Notches positioned every 15 degrees Used for piston position identification Pressed onto crankshaft Must be serviced with crankshaft Knock sensors: Two sensors on GEN III V8 Internally mounted in engine valley Detonation when signaled PCM reduces ignition timing advance Replace if sensor is dropped or over-torqued 4.0L and 4.6L Direct Ignition System (DIS) 4.0/4.6L V8 DIS: Waste spark system Dual variable reluctance CKP sensors One reluctor ring 24 evenly spaced notches 8 unevenly spaced notches "B" sensor mounted 27 degrees of crankshaft revolution behind "A" Fires first coil in less than 180 or one half crankshaft revolution Ignition module counts "B" pulses between "A" pulses: Four patterns of B’s between A’s: 0112, 01012, 01111, and 010111 Ignition can sync at four different crankshaft positions CMP sensor used for fuel control and misfire diagnostics 3.0L and 3.8L C3I: Hall effect switches for crank and cam position Interrupter ring mounted on back side of harmonic balancer Ignition module Coil pack assembly: Type I Type II Fast Start uses unique interrupter ring to give: More precise crank information Faster starts without relying on cam signal CKP sensor on 3.0 liter engine is located adjacent to harmonic damper Concentric rings on damper pass on each side of Hall Effect magnet Inner ring has 3 evenly spaced vanes and windows Outer ring has only 1 window On 3.8 liter SFI and SFI turbo engines, synchronize signal is determined by camshaft sensor C3I fast start: Uses dual CKP sensor and separate CMP sensor Advantages: Faster start-up Walk-home protection in case of cam sensor malfunction More precise crankshaft sensor signal measurement Fast start systems: Crank sensors mounted beside harmonic balancer CMP sensor mounted on timing cover Outside ring produces pulses known as 18x signal Inside ring produces pulses referred to as 3x signal CKP sensor adjustment on 3300/3800 V6 - use adjusting tool, part number J-37089: Ensures accurate positioning of sensor Maintains proper clearance between interrupter vanes and sensor Checks interrupter rings for out-of-round 3100/3400 ignition system: Uses two crankshaft position sensors 24x CKP signal (direct input to PCM) 7x CKP signal (input to the IC module) IC module sends conditional 3x signal to PCM Below 1250 RPM, PCM uses CKP 24x signal 3x reference low: PCM uses 3x signal to calculate engine speed and crankshaft position over 1250 RPM If PCM receives no pulses on this circuit: DTC P1374 sets PCM uses 24x reference signal circuit for fuel and ignition control Camshaft position sensor (CMP): Sends cam position signal to PCM: Used as sync pulse to trigger injectors Used to indicate position of #1 piston If PCM detects incorrect CMP signal with engine running, DTC P0341 sets If CMP signal lost while engine running, engine will continue to run Engine can be started and run in calculated sequential mode Compression Sense Ignition CSI System 2.2L engine (RPO L-61): Uses waste spark electronic ignition system referred to as CSI PCM determines proper engine phasing without a separate camshaft position sensor Compression Sense Ignition (CSI): Similar to ignition systems on premium V-6 and V-8 engines Both house components in a single cassette L-61 uses compression sense Cassette mounted over spark plugs Houses two ignition coils Cylinders 1 & 4 paired in one coil Cylinders 2 & 3 paired in the other Spark plug firing: One plug in each pair fires from center electrode to side electrode Other plug fires from side to center One cylinder's firing voltage rises in a negative direction, breaks in positive direction toward ground Other cylinder's firing voltage rises in positive direction, breaks in negative direction toward ground Polarity is one part of information reflected in CSI signal Breakdown: As ignition coil fires, growing voltage potential is created across gaps of both plugs Voltage reaches breakdown after 10 microseconds Breakdown voltage determined by pressure within cylinder - more voltage needed at higher pressure Spark plug on exhaust stroke fires first Order of spark plug breakdown events is another characteristic in CSI signal Compression sense ignition sensor: Compression sense ignition sensor used to detect polarity and breakdown in secondary ignition circuits of each pair Accomplished by creating virtual capacitors between secondary coils and EI electronics Voltage measured across resistor makes up information in CSI signal Polarity and timing: Cylinders fire in pairs Voltage of plug moves toward positive while its pair moves toward negative Plug in exhaust fires first CSI signal reflects polarity and timing of spark plug breakdown event Polarity and timing: Cylinders fire in pairs Voltage of plug moves toward positive while its pair moves toward negative Plug in exhaust fires first CSI signal reflects polarity and timing of spark plug breakdown event Compression Sense Time Out (CSTO) continued: Variable reluctance CKP sensor mounted in engine block near crankshaft Crankshaft has seven notches, seventh used for sync pulse Engine starts firing 2-3 coil during cranking Once ignition process has started, PCM looks for sequence of CAMOUT signals to determine engine phasing Takes into account engine operating conditions In-cylinder pressures for pairs can be equal PCM considers CSI signal valid only during certain MAP ranges HVS distributor ignition system: Each engine application has unique distributor: 4.3L V6 is non-adjustable 5.0L, 5.7L, 7.4L V8 are adjustable Trigger for ignition timing supplied by magneto-resistive type CKP sensor CMP sensor used to sequence fuel injectors and for on-board misfire diagnostics HVS distributor: Appearance similar to typical distributor Rotating HVS distributor does not change ignition base timing VCM contains base timing information within its calibration Ignition coil driver module: Mounted with high energy coil VCM controlled Controls current through primary windings of coil CKP sensor determines base timing HVS distributor ignition system: Uses CKP and CMP signals as inputs to VCM VCM uses IC signal to control advance and retard Distributor on V8 applications adjusted to eliminate crossfire