MoTeC SKM and OKM User Manual
Contents
1. Connector 3 ECU MoTeC Appendices 29 Appendix 4 Gold Wave Settings To set up the side display as a Spectrogram for analysing frequency of sounds On the Options menu click Control Properties keyboard shortcut F11 GoldWave File Edit Effect wiew Tool ESA Window Help Colour Control Properties File Formats Plug in Storage Tool Bar Window In the Left Visual box select Spectrogram lt GoldWave gt Control Properties Be Play Record Volume Visual ma Device BA Test Status visual Level visual Time and Status GoldWave gt sw VU Meter lt Gold Wave gt ka Left visual Right visual Spectrogram lt GoldWw avet gt Spectrogram Goldi ave gt Bulge lt GoldWave gt Envelope lt Gold Wave gt Spectrogram saal ave Spectrum lt GoldwWayve gt i di Spinning Logo lt Gold wWawe gt AEREE VU Meter lt GaldWave gt Waveform lt GoldWayve gt FFT window Y Graph lt GoldWave t gt J Envelope lt soldWave gt Spectrogram lt GoldWwave gt Spectrum lt GoldWwave gt Spinning Logo lt GoldWave gt 30 Appendices On the Tool menu click Control Right click in the screen to open the menu and select Spectrogram lt GoldWave gt Click Properties to configure the spectrogram Choose Fixed frequency range and set range to From Hz 3000 To Hz 18000 Choose Show Axis Spectrogram C Automatic full frequency range F2. 4 Knock 2 Knock 3 5 Knock 4 5 Knock Limit 3 Misture Map 4 APM Histogram 5 Drive By Knock Retard Short 1 Knock Retard Short 2 Knock Retard Short 3 Knock Retard Short 4 Knock Retard long 1 Knock Retard long 2 Knock Retard long 3 7 Knock Retard long 4 Mis 22 1 24 1 26 1 28 1 30 1 32 1 34 1 36 ie i2 data showing the instantaneous short and long term retard effect on knock levels MoTeC Configuration 19 The knock control settings are adjusted in ECU Manager software e On the Adjust menu click Functions e Click Knock Control e Click Setup to enter Knock Control and set the following parameters Activate Throttle Pos Specifies the throttle position which must be exceeded to activate knock control 0 Disabled knock control always active Unit Percentage Activate Full Throttle Time Knock control will only activate when the full throttle timer exceeds this value 0 Off Ignore full throttle timer Units seconds Maximum RPM Knock control is disabled once Engine RPM exceeds this value Useful when background noise becomes excessive and clear knock detection is no longer possible Normally set to 50 RPM below the RPM limit as engines running on the RPM limit may knock intermittently Mode 0 Individual cylinder knock control 1 Global knock control All cylinders will be retarded equally Usually set to 0 If set to 1 the contr
3. are represented as a percentage The absolute value is at this moment not relevant Important is a low background noise level and a high actual knock signal The log file with a setting of 8 KHz might equal background noise levels of approximately 60 and mild knock shows peaks of 90 A log file with a setting of 5 kHz might equal background noise levels of approx 25 and mild knock showing peaks of 70 Therefore a centre frequency setting of 5 KHz would in this example likely be the best Note The centre frequency will affect the overall level of the knock voltage channel 14 Configuration 17 0k 16 0k 4 15 5k 7 0 6 5 6 0 Frequency spectrogram in GoldWave MoTeC Configuration 15 Example 2 The Mitsubishi Evolution Lancer series has a narrowband knock sensor that transmits a signal different to wideband knock sensors The voltage amplitude is high compared to signals from wideband sensors for the same level of engine noise so overall energy levels will be high The next spectrogram shows a signal from a narrowband knock sensor It shows severe detonation at the 2 seconds mark yellow energy spikes The background noise and detonation is concentrated on one frequency in this case13 kHz Background noise 50 5 5 5 0 45 40 35 30 25 20 1 5 14 0 0 5 0 renpeeeepteee eee 100 30 80 70 60 50 40 30 20 10 0 Mitsubishi Evolution Lancer knock frequency analysis With an exa
4. associated hardware by comparing the sound of the engine with and without detonation Frequency analysis will determine the theoretical best centre frequency This is the frequency where the difference of the engine sound with and without detonation is most clear to detect Surprisingly minor changes to the engine hardware will affect the frequency of the detonation ring throughout the structure So frequency settings that suit one car may not be suitable for another car of the identical model but with slight modifications Warning Knock frequency analysis is a specialised job to be carried out by experienced technicians Incorrect operation can easily cause severe engine damage Setup 1 Using the SKM tuning loom connect an audio lead to the line in or microphone in port on the PC The PC must be able to record sounds through a line in port and simultaneously play it to the headphone jack so the operator can listen and monitor the engine while recording Note If your computer does not have the ability to record and listen at the same time an alternative method should be used to listen to the engine e g an external sound card or third party device 2 Configure the PC to play sound only from the left channel The right channel is the knock window signal sent from the ECU Tip You can make an adapter plug for the headphones that joins the sound from the left and right channel 3 Connect audio headphones to the PC Tip To b
5. detonation 8 Configuration The knock module filters and amplifies the signal transmitted from the knock sensor based on the centre frequency Signals of the selected centre frequency pass the frequency filter amplified while signals in other 4 6 8 1012 14 16 kHz frequencies will be reduced The mgn further away from the centre O frequency the more the signal will Ko be reduced Filtering will reduce the S influence of background engine 3 noise resulting in improved knock E detection e The figure shows frequency based is et cn de low amplification with the centre frequency set to 12 kHz Frequency based amplification Gain Factor A gain factor is only required for knock sensors with very low output levels The gain factor can be chosen to multiply the raw knock output signal prior to frequency filtering It is also possible to set a gain factor from ECU Manager software Knock Module Configuration The configuration of the Knock Modules consists of two stages Stage 1 Carrying out a frequency analysis of the knock sensor signal to determine the centre frequency and knock module settings This needs to be done by a competent tuner as incorrect operation can easily result in severe engine damage Stage 2 Tuning the knock control system Note The OKM settings are preconfigured to suit the standard vehicle It only requires the second configuration stage to tune the knock system If the vehicle is modified signi
6. frequency settings for each application MoTeC Configuration 17 Example 3 The car from the previous example has been converted to rally specifications This involved fitting a roll cage larger exhaust etc Other than a restrictor the engine remains unchanged The knock sensor signal is now concentrated on 12 kHz rather than 13 kHz and the characteristics are different In this case a centre frequency of 6 kHz may be more appropriate Tkhz Frequency Change in background noise Mitsubishi Evolution Lancer rally spec knock frequency analysis Centre Frequency Setting After the knock frequency has been assessed and a centre frequency chosen the Knock Module must be setup accordingly For instructions on changing the SKM switch settings see appendix 1 Note The OKM settings are preconfigured to suit the standard vehicle However should adjustment be required because the vehicle is modified significantly contact an authorised MoTeC dealer for further advice 18 Configuration Tuning Knock Control System Note The following tuning is a specialised job to be carried out by experienced technicians Incorrect operation can easily cause severe engine damage The knock control system will retard the ignition timing depending on the level of knock There is an instantaneous setting to reduce the knock levels immediately and a long term retard setting to prevent knock re occurring 1 Default v 1 General 2 Knock Knock 1
7. MoTeC SKM and OKM User Manual Contents INIFOGUCHOM sciiiecini ai 2 Getting Starte d a 4 Insialialioia a Gc 5 lr 5 OKM oee arco 5 CONnligurationi aia a 6 Knock Detection serorea ici 6 Knock Module Configuration ii 8 Operaio aisi 23 APPENDICES Lira 24 Appendix 1 SKM Internal Dip Switch Settings 24 Appendix 2 SKM Connector Pin Out and Wiring 26 Appendix 3 SKM Tuning Loom 61114 27 Appendix 4 Gold Wave Settings 29 Appendix 5 Detonation Explained 31 ESD Antistatic All necessary antistatic precautions must be taken while handling circuit boards Copyright 2008 MoTeC Pty Ltd The information in this document is subject to change without notice While every effort is taken to ensure correctness no responsibility will be taken for the consequences of any inaccuracies or omissions in this manual Version 1 0 24 October 2008 2 Introduction Introduction MoTeC s Knock Modules provide individual cylinder closed loop knock control allowing tuners to safely optimise high performance ignition maps There is a standalone module compatible with all hundred series ECUs and a version specifically designed to mount onto an M800 Plug In ECU Both modules work in conjunction with MoTeC s ECU Manager software v3 5 and up Standalone Knock Module SKM This module is housed in a robust al
8. auses an immediate rise in the temperature of these parts often leading to direct failure or at least to engine overheating Detonation Causes The potential for detonation is influenced by chamber design elements including shape size geometry plug location compression ratio engine timing mixture temperature cylinder pressure and fuel octane rating Too much spark advance ignites the mixture too soon increasing the pressure resulting in spontaneously combustion Preventing Detonation With the engine configuration set detonation can be reduced by reducing ignition timing reducing air fuel intake temperature i e making the mixture richer or using a larger intercooler Reducing Coolant Temperature Using a fuel with a higher octane rating MoTeC Notes 35 36 Notes
9. detonation occurs 4 The colour change occurs at the knock frequency but there are often reflections of the detonation at other frequencies 5 Determine the frequency where the difference of the engine sound with and without detonation is most clear to detect This will be the centre frequency setting MoTeC Configuration 13 Examples The following examples show how to interpret the data and choose the centre frequency Example 1 In the next spectrogram increased energy levels show consistently at 8 kHz The noise at this frequency is constant even when the engine is not detonating therefore we can assume that this is normal engine background noise Detonation introduced via an ignition timing adjustment in the ECU can be seen at the 3 5 second mark Here extra energy levels are seen throughout all frequencies To determine which frequency has the best ratio between little background noise energy and high detonation intensity compare the areas with and without detonation In the example at 5 KHZ there is little background noise and a touch of yellow high energy at the detonation point The highest detonation energy is at 8 KHz however the background noise is also high here To help selecting the best centre frequency experiment with different settings while downloading the log files from the ECU Analyse the log files using 2 data analysis software The log files will show the individual cylinder knock channels They
10. e cylinders knock percentage channels The Knock Table is configured with RPM as X axis As a starting point values are to be entered at 5 to 10 above background noise levels e When all Knock Table settings are completed click ESC e Click Gain to enter the Knock Gain Table This table compensates any sensitivity difference of the sensor to particular cylinders The Knock Gain table should be used in conjunction with the Knock Offset table to level out any differences between the individual cylinders Typical starting value 1 00 Note The values in this table must be non zero to show any Knock Percentage values e When all Gain settings are completed click ESC e Click Offset to enter the Knock Offset Table This table compensates for any offset differences of the sensor to particular cylinders The Knock Offset table should be used in conjunction with the Knock Gain table to level out any differences between the individual cylinders Typical starting value 0 22 Configuration Knock Tuning Tips Set both Retard Limit and Retard Limit Long Term to 0 degrees Listen for detonation while running the engine Introduce light detonation very carefully and log the knock percentages Estimate the Ignition Retard required preventing this level of knock continuing Adjust the Instantaneous Term trim parameters Start with values which will cause too much retard Work your way back until an appropriate strategy for the
11. ed from the MoTeC website at www motec com Further information on ECU Manager software can be found in the ECU User Manual For frequency analysis MoTeC recommends Gold Wave Audio Analysis Software A trial version can be downloaded from www goldwave com PC requirements e Operating System Windows XP and up e Audio and USB input e Sound card capable of simultaneously recording and playing Alternatively an external soundcard or third party device can be used MoTeC Installation 5 Installation SKM The SKM is connected between the OEM fitted knock sensor and a hundred series ECU M400 M600 M800 or M880 The SKM knock signal output must be connected to the ECU via an available analogue voltage input preferable a Lambda sense input The Lambda sense input has a slightly higher resolution To send the gated window signal to the knock module connect a spare injector or ignition output on the M800 or M880 ECU to the SKM input On the M400 and M600 injector 8 output must be used Alternatively the SKM Tuning loom can be used available separately See appendix 2 and 3 for detailed wiring instructions cannes c SKM knock signal Knock knock sensor window Hundred series ECU OKM The OKM is fitted directly onto the board of an M800 Plug In ECU Most M800 Plug In ECUs fitted with an OKM are pre configured to analogue voltage input AV5 and ignition output 6 WRX9 10 boards use lambda 1 sense inpu
12. es the engine may smoke but more often the driver is not aware detonation is occurring Typical results of detonation are broken piston ring lands broken spark plug porcelains or broken ground electrodes However these signs are usually not spotted externally It is also difficult to detect detonation while an engine is running in a remote and insulated dyno test cell To help hear detonation a very elementary technique often proves successful run a copper pipe bolted flat to the side of the engine block into the control room place a funnel at the end to amplify the sound through the pipe and listen This allows the operator to hear all mechanical noises within the engine and helps to identify detonation should it occur Also commonly used for knock detection are electronic amplifiers These devices either connect directly to a Knock sensor or use an alligator clip placed on the engine block The engine sounds are amplified and filtered and then routed to the operator via headphones Detonation Failures Detonation causes three main types of failure 1 Mechanical damage broken ring lands hammered big end bearings The high impact nature of the pressure spike can also cause fractures it can break the spark plug electrodes the porcelain around the plug cause a clean fracture of the ring land and in severe cases can actually cause fracture of valves intake or exhaust 2 Abrasion pitting of the piston crown The sandblasted appea
13. ficantly contact an authorised MoTeC dealer for further advice Before carrying out any stage of the configuration the vehicle needs to be prepared by setting up the ECU for knock measuring and data logging using ECU Manager software MoTeC Configuration 9 Preparation Configuring the Knock Window e On the Adjust menu select injector ignition output functions e Select injector ignition out Select injector or ignition output the SKM OKM is wired to Note For M400 M600 Inj8 must be used e Select Function e Type Function value 122 Knock Window e Press ESC e Select Parameters Start Ref 0 knock window measured after ignition point 1 knock window measured after TDC Typical value 1 Start Angle The starting angle of the knock window in the engine cycle where the knock sensor signal is recorded Unit degrees Typical value 10 Slow End Angle The end angle of the knock window in the engine cycle when operating at slow engine RPM up to 1000 RPM Unit degrees Typical value 40 Fast End Angle The end angle of the knock window in the engine cycle when operating at fast engine RPM RPM as specified in RPM Limit Unit degrees Typical value 50 Polarity 0 output high for 0 duty 1 output low for 0 duty Value 0 is required for SKM OKM 10 Configuration Configuring the channel Knock Voltage e On the Adjust menu click Sensor Setup e Click Input Setup this will open the Input Pins Setup scree
14. h this pressure build up to detonation occurs is greater than the speed at which the mixture burns the pressure waves from both the initial ignition at the spark plug and the pressure waves coming from the problem spots can set off immediate explosions in the remaining air fuel mixture rather than smooth combustion The remaining fuel in the end gas simply lacks sufficient octane rating to withstand this combination of heat and pressure MoTeC Appendices 33 Detonation causes a very large very rapid pressure spike of very short duration in the combustion chamber The pressure trace of the combustion chamber process would show the normal burn as a steady pressure rise and then all of a sudden a very sharp spike when the detonation occurred The pressure spike creates a force on the combustion chamber causing the structure of the engine to ring or resonate much as if it were hit by a hammer Resonance which is characteristic of combustion detonation occurs between 4 to 12 kHz resulting in the audible pinging This noise or vibration is what the knock sensor detects Detonation Indicators The best indication of detonation is the pinging sound that cars particularly old models pre 1980 make at low speeds and under load It is very difficult to hear the sound in the well insulated luxury interiors of today s cars An unmuffled engine running straight pipes or a Rally Car racing on a gravel road can easily mask the sound In some cas
15. ignal captured using Gold Wave Audio Analysis Software www goldwave com Audio signal output from a knock sensor MoTeC Configuration 7 With increasing engine RPM the higher engine vibrations will result in an increase in the amplitude of the knock sensor signal A race engine operating at high RPM will show high amplitudes making it difficult to detect knock W rpm test 1 2 3 4 5 6 way Knock sensor signal with increased engine RPM Knock Modules The SKM OKM modules improve knock detection by reducing the influence of background engine noise using a combination of data gating and frequency filtering Data Gating The knock window is the period in the combustion cycle during which knock is likely TDC to occur normally between 10 and 50 degrees start angle after TDC top dead centre The ECU sends a knock window signal to the Knock Module to mark the start and end angle in the engine cycle The SKM OKM will measure the knock sensor signal during this window and sends the information to the ECU The ECU uses the measurement to calculate the knock percentage for each cylinder of the engine Knock window end angle Frequency Filtering To correctly identify knock the SKM switches must be set to match the theoretical best centre frequency The centre frequency in the SKM OKM is normally set to the frequency of the engine that shows the greatest energy difference between normal engine operation and active
16. ixed frequency range From Hz 13000 To Hz 18000 J Show axis Cancel Apply Help MoTeC Appendices 31 Appendix 5 Detonation Explained Detonation also called spark knock is an erratic form of combustion that can cause catastrophic engine failure Detonation occurs when excessive heat and pressure in the combustion chamber causes the air fuel mixture to self ignite This produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise The hammer like shock waves created by detonation subject the head gasket piston rings spark plug and rod bearings to severe overloading Mild or occasional detonation can occur in almost any engine and normally causes no harm But prolonged or heavy detonation can be very damaging Detonation is the result of an amplification of pressure waves such as sound waves occurring during the combustion process when the piston is near top dead centre TDC The actual knocking or ringing sound of detonation is due to pressure waves pounding against the insides of the combustion chamber and the piston top It is not due to colliding flame fronts or flame fronts hitting the piston or combustion chamber walls Normal Combustion This is the burning of a fuel and air mixture charge in the combustion chamber It should burn in a steady even fashion across the chamber originating at the spark plug and progressing across the chamber i
17. le AV input 3 Snook ECU M400 M600 M800 M800 preferable a Lambda sense input Se tells 3 5 mm stereo connector tip left channel Audio Ground 3 5 mm stereo connector ring ground Sensor 1 Input knock sensor signal Sensor 2 Input Sensor 3 Input M400 M600 injector8 only any spare ignition or Knock M800 M880 injector output Window via 100 KQ resistor to 3 5 mm stereo connector ring right channel M400 M600 M800 M880 8 V 3 M400 M600 M800 M880 ground 6 T 8 MoTeC Appendices 27 Appendix 3 SKM Tuning Loom 61114 Optionally the SKM Tuning Loom can be used for wiring e Length of the ECU and knock sensor leads is 600 mm e Length of the audio lead is 1850 mm Connector 1 Stereo plug Base Audio Ground Middle right channel Knock Window Tip left channel Knock Audio Out Connect to stereo headphones Connector 2 DTM 2 pin Mating connector 68051 Pin Function Connect to knock sensor 1 2 Shield Shield Knock Signal Signal Connector 3 DTM 4 pin Mating connector 68054 Function Connect to M400 M600 M800 M880 Knock ECU Any available AV input preferable a Lambda sense input gt Window Note on M400 M600 injector8 only Any spare ignition or injector output 28 Appendices SKM connector NC NC blue knock ECU out white knock audio out black audio ground green knock signal Connector 1 Audio Connector 2 Knock sensor
18. lied per second for each degree of instantaneous term trim retard applied Unit Degrees Second Degree e g Retard Rate Long Term 0 200 and currently active Instantaneous Term trim 8 degrees then 1 6 degrees second long term trim is also applied Advance Rate Long Term Long term rate at which ignition is advanced back to normal Unit Degrees Second e g Advance Rate Long Term 0 050 would result in the ignition to advance back at a rate of 1 degree in 20 seconds Retard Limit Long Term Maximum amount of long term retard the Knock Control function can remove from the current ignition timing from Ignition Table MoTeC Configuration 21 This is added to the value in Retard Limit for the Instantaneous term trim Unit Degrees e g Retard Limit 10 Retard Limit Long Term 6 and current ignition timing 25 degrees BTDC then the Knock Control Function can retard to 25 10 6 9 degrees e When all parameter settings are completed click ESC e Click Knock Table to enter the Knock Table window This table sets the Knock Target Threshold or Knock Limit for the Knock Control function The ignition will not be retarded unless the measured knock value of any of the cylinders exceeds the Knock Target Threshold value To determine Knock Target Threshold values run the engine in a non knocking condition with safe ignition timing Operate the engine fully loaded through all RPM levels and note the background noise levels in th
19. lock out external engine and car noise bud type ear phones with high quality ear muffs used over top can be used 4 To perform frequency analysis on the recorded audio file requires dedicated software In this document Gold Wave software is used in all examples See Appendix 4 Gold Wave Settings 12 Configuration Test 1 Ensure the engine is at normal operating temperature 2 Run the engine and listen for any irregularities in engine vibrations like internal component noise 3 Ifall sounds normal bring the engine under some load and carefully introduce light detonation Tip To introduce detonation at as light a load as possible use a low octane fuel 4 Proceed with extreme caution and note where detonation can be introduced Return to no detonation 5 Open a new file in Gold Wave and record the data while running the engine from a normal operating situation to a situation with detonation at a similar engine speed 6 Shut down the engine Analysis 1 Configure the Gold Wave Software so that the sound recording can be viewed on a spectrogram see appendix 4 2 Play back the Gold Wave audio file The Y axis on the spectrograms chart is the frequency range the X axis is the playback time The colours on the chart represent the energy of the recorded sound The key to the colours is underneath the X axis 3 Look at the spectrogram chart while listening for detonation The colour in the spectrogram changes at the moment
20. mple setting of 13 kHz the log file from the ECU might show background noise level at 50 70 and mild knock showing peaks of 90 This makes it difficult to detect severe detonation so an SKM OKM centre frequency setting of 13 kHz would be inappropriate The detonation energy is high enough to reflect through other frequencies For example at 7 kHz there is less background noise and still relatively high detonation intensity With a setting of 7KHZ the log file from the ECU might show background noise level at 30 40 and mild knock at 60 With this setting larger detonation events can be measured with appropriate action taken as a result This would therefore be a better choice for the correct setting 16 Configuration lei x fle yew Lent dd Data Component Tock Heb MoTeC J dba da Siz ios RARA Jld ihrotlie Pos 7a Ge start BLA Greer reeset ouioh fi moter eou Manage SB ree O amets and Seti EI Matec 2 Pre ren Fo Y brock bow back ganan ADTOK ize roret i rro RO Pe EEE alaj xj fie a ye Lat doi Qes Component Jods bep UnA 3 MINO LAP ISTE i iS gt at Gt el Tino RGS RI Otc Ohl ate stare S DI RR Fido crono cui fat Matec ecu manage 8 moaia CNpcuments and Sem FE Motec ve FED Fo _ med nowy backgrounds AJOKO num Logi file from ECU with a centre Teeney setting of 7 kHz This example highlights the complexity involved in determining knock and appropriate centre
21. n e Click the Other tab e Select Knock Voltage Knock V e Click Change e In the Input Source list click AV or Lambda Select the input the SKM OKM is wired to e Inthe Calibration area select Predefined and in the list click 31 Volts V x1 5 000V 5 000V Knock Gain Table e On the Adjust menu click Functions e Click Knock Control e Click Gain This table compensates any sensitivity differences of the sensor to particular cylinders The Knock Gain table should be used in conjunction with the Knock Offset table to level out any differences between the individual cylinders Typical starting value 1 00 Note The values in this table must be non zero to show any Knock Percentage values Data Logging Setup Each cylinder s knock input should be logged at 50 Hz or greater e On the Adjust menu click Data Logging Setup e Click Knock Levels e Select Knock Limit and type 10 e Select Knock 1 and type 50 or greater e Continue the last step for all remaining cylinders in firing order Follow the same procedure to log other useful channels Recommended channels are e Knock Retard Short Term for each cylinder e Knock Retard Long Term for each cylinder e Individual Ignition Advance channels to evaluate the performance of the control system during calibration tuning MoTeC Configuration 11 Frequency Analysis A competent tuner with the right equipment can measure and analyse the knock frequency for the specific engine and
22. n a three dimensional fashion Similar to the ripples spreading out when a pebble is thrown into a pond with a glass smooth surface the flame front should progress in an orderly fashion The burn moves all the way across the chamber and quenches i e cools against the walls and the piston crown The burn should be complete with no or very little remaining unburnt fuel air mixture Note that the mixture does not explode but burns in an orderly fashion During combustion the location of peak pressure LPP can be measured with an in cylinder pressure transducer When the spark is fired at optimum timing the burn is initiated at the spark plug and will progress evenly through the chamber to reach peak pressure shortly after top dead centre depending on the chamber design and the burn rate Ideally the LPP should occur between 12 and 15 degrees after top dead centre 32 Appendices Flame Front Boundary Layer Combustion chamber at TDC N Detonation Area Pressure Waves Squish Abnormal Combustion Detonation If conditions for combustion are not ideal detonation can occur This usually happens first at points of amplification of the pressure waves TDC Combustion Pressure with detonation For example at the edges of the piston crown where reflecting pressure waves from the piston or combustion chamber walls can constructively recombine this causes very high local pressures If the speed at whic
23. ol system will retard all cylinders regardless of the cylinder on which the knock was measured Error Retard Specifies the amount of permanent retard that will be applied to all cylinders if the knock sensor goes into error as defined by the diagnostic levels in the input setup Unit Degrees Warning Trigger Specifies the level above the Knock Target Threshold value from Knock Table which if exceeded will cause a warning to be generated 20 Configuration Note Requires the Driver Warning Alarm function to be configured on an auxiliary output Note The knock warning is included in Status Group 3 Unit Percentage Retard Gain Instantaneous Term Defines the amount of retard applied for each percent over the Knock Target Threshold value from Knock Table Unit Degrees Percent e g Retard gain 0 5 and knock 20 over the Knock Target Threshold would result in 10 degrees ignition retard Advance Rate Rate at which ignition retard is advanced back to normal Unit Degrees Second e g Advance rate 2 would result in the ignition to advance back at a rate of 2 degrees per second Retard Limit Maximum amount of retard from the current ignition timing from Ignition Table Unit Degrees e g Retard Limit 10 and current ignition timing 25 degrees BTDC then the Instantaneous term trim aspect of the Knock Control Function can retard to 15 degrees BTDC Retard Rate Long term Amount of long term retard app
24. rance to the top of the piston near the perimeter the piston is typical if detonation occurs Examined with a 34 Appendices microscope the small holes are not unlike those found in Swiss cheese The detonation actually mechanically erodes material out of the piston Typically the sandblasted look can be expected in the part of the chamber most distant from the spark plug Overheating scuffed piston skirts due to excess heat input or high coolant temperatures Because the pressure spike is very severe and of very short duration it can actually shock away the boundary layer of gas that surrounds the piston Normal combustion temperatures exceed 900 deg Celsius An aluminium piston subjected directly to that temperature would melt Under normal combustion it does not melt because of its thermal inertia and because of a boundary layer of air fuel mixture a few molecules thick next to the piston top This thin layer isolates the piston from the flame and causes the flame to be quenched as it approaches this relatively cold material This protects the piston and chamber from absorbing the heat of the combustion However under extreme conditions the shock wave from the detonation spike can cause the boundary layer to breakdown Since pressure waves created during detonation can sweep away these unburned boundary layers of air fuel mixture they leave parts of the piston top and combustion chamber exposed to the flame front This in turn c
25. t rather than AVS 6 Configuration Configuration When suffering detonation each engine chassis combination and associated accessory package resonates at different frequencies To configure an electronic knock control system the exact combination of engine engine mount exhaust system alternator and starter etc must have been fitted A reliable electronic knock control system requires detecting knock accurately and differentiating knock from normal engine noise MoTeC s knock modules use the vehicle s original factory fitted knock sensors to detect detonation improving this detection by reducing the influence of background engine noise using a combination of data gating and frequency filtering The engine sound energy during engine operation will vary for different frequencies in the spectrum The knock sound energy will be more prominent at certain frequencies A competent tuner needs to carry out a frequency analysis to determine the frequency where the difference of the engine sound with and without detonation is most clear to detect The centre frequency settings of the Knock Module must match this frequency The Knock Control system in the ECU can then be configured to adjust the ignition according to measured knock levels Knock Detection Knock Sensor The knock sensor measures the engine vibrations and turns this into an AC waveform output The next figure shows a zoomed in view of typical knock sensor s
26. type of engine is found To start work with Instantaneous Term trim only Add the Long Term trim parameters later if required MoTeC Operation 23 Operation Once the Knock Control System is tuned it can be used for continuous monitoring The configuration will generally not need any adjustment Only major changes in engine exhaust cams pistons etc and transmission might require a new centre frequency setting In this case the vehicle should be returned to the dealer for a new frequency analysis 24 Appendices Appendices Appendix 1 SKM Internal Dip Switch Settings Dip switches are used to set the gain factor centre frequency and the differential mode switch To access the switches remove the 4 lid locating screws Hold the device as shown in the photo to see the various switch identification codes SKM Dip Switches Switch down toward the circuit board on Switch up away from circuit board off MoTeC Appendices 25 Differential Mode Switch normal knock sensor connection default on differential sensors Gain Switches Gain 4 16 16 32 n 64 0 FO Frequency 5 kHz off on O 8 kHz on off off O 9 kHz on on on O 10 kHz default n o on 12 kHz off 14 kHz n n 26 Appendices Appendix 2 SKM Connector Pin Out and Wiring Connector Autosport 13 pin Mating connector 65041 Connect to e rn owners ut Selecto I i I Seleet4 any availab
27. uminium casing that can be mounted as required in any vehicle It is wired between the ECU and the knock sensor Onboard Knock Module OKM This module is fitted onto the board of an M800 Plug In ECU prior to delivery and linked to the knock sensor M800 Plug In ECUs are available for selected vehicles Please check our website at www motec com au for details Basic Specifications OKM Inputs Knock sensor input Knock window input Power supply 8 V Outputs Knock sensor out e Audio Audio Physical Case size 38 x 90 x 25 mm e Fitted onto a M800 Plug In excluding connector ECU Weight 100 grams 1 x 13 pin Autosport connector MoTeC Introduction Other information OKM hundred series ECUs e M800 Plug In ECUs M400 M600 M800 and M880 All knock sensors Related ECU Manager software e ECU Manager software software v3 5 and up v3 5 and up software version 2 3 software version 2 3 enables monitor only enables monitor only i2 Data Analysis e i2 Data Analysis Gold Wave Audio e Gold Wave Audio Analysis Software for Analysis Software for frequency analysis only frequency analysis only Accessories Stereo headphones e Stereo headphones e Knock sensor e SKM tuning loom 61114 optional 4 Getting Started Getting Started The Knock Modules have no stand alone Manager software All Knock control configuration is done through MoTeC s ECU Manager software version 3 5 or up This can be download
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