MoTeC SKM and OKM User Manual Contents Introduction ................................................................................ 2 Getting Started ........................................................................... 4 Installation .................................................................................. 5 SKM ......................................................................................................... 5 OKM....................................................................
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.
MoTeC Introduction Other information Compatibility Related software Accessories SKM y ‘hundred series’ ECUs; M400, M600, M800 and M880 y All knock sensors y ECU Manager software v3.5 and up (software version 2.3 enables monitor only) y i2 Data Analysis y Gold Wave Audio Analysis Software (for frequency analysis only) y Stereo headphones y Knock sensor y SKM tuning loom #61114 (optional) OKM y M800 Plug-In ECUs y ECU Manager software v3.5 and up (software version 2.
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 downloaded 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.
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.
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 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. 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.
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 frequencies will be reduced. The further away from the centre frequency, the more the signal will be reduced. Filtering will reduce the influence of background engine noise resulting in improved knock detection.
MoTeC Configuration 9 Preparation Configuring the Knock Window y On the Adjust menu select injector/ignition output functions y Select injector/ignition out [#] Select injector or ignition output the SKM//OKM is wired to. Note: For M400/M600 Inj8 must be used.
Configuration Configuring the channel Knock Voltage y On the Adjust menu click Sensor Setup y Click Input Setup… this will open the Input Pins Setup screen y Click the Other tab y Select Knock Voltage (Knock V) y Click Change y In the Input Source list click AV[#] or Lambda[#] (Select the input the SKM//OKM is wired to) y In the Calibration area select Predefined and in the list click #31 Volts(V); x1 (5.000V=5.
MoTeC Configuration 11 Frequency Analysis A competent tuner with the right equipment can measure and analyse the knock frequency for the specific engine and 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.
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. If all 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.
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.
Configuration 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).
Configuration Log file from ECU with a centre frequency setting of 13 kHz Log file from ECU with a centre frequency setting of 7 kHz This example highlights the complexity involved in determining knock and appropriate centre 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.
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.
MoTeC Configuration 19 The knock control settings are adjusted in ECU Manager software. • On the Adjust menu click Functions • Click Knock Control • 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.
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.
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. • When all parameter settings are completed, click ESC • Click Knock Table to enter the Knock Table window This table sets the Knock Target Threshold (or Knock Limit) for the Knock Control function.
Configuration Knock Tuning Tips y Set both Retard Limit and Retard Limit Long Term to 0 degrees. y Listen for detonation while running the engine. y Introduce light detonation very carefully and log the knock percentages. y Estimate the Ignition Retard required preventing this level of knock continuing. y 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 type of engine is found.
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.
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.
MoTeC Appendices Differential Mode Switch DM off on Function normal knock sensor connection (default) differential sensors Gain Switches G2 On On On On Off off off off G1 on on off off on on off off G0 on off on off on off on off Gain 2 (default) 4 8 16 16 32 64 128 Knock Centre Frequency Switches F3 off off off off on on on on on F2 on on on off off on on on off F1 on off off on off on off off on F0 on on off on on on on off on Frequency 5 kHz 6 kHz 7 kHz 8 kHz 9 kHz 10 kHz (default) 12 kHz 14
Appendices Appendix 2 SKM Connector, Pin Out and Wiring Connector Autosport 13 pin Mating connector #65041 SKM Connect to Pin Function Device/connector Input 1 Select 0 2 Select 1 3 Knock ECU Out M400/M600/M800/M800 any available AV input, preferable a Lambda sense input 4 Knock Audio Out 3.5 mm stereo connector tip (left channel) 5 Audio Ground 3.
MoTeC Appendices 27 Appendix 3 SKM Tuning Loom #61114 Optionally the SKM Tuning Loom can be used for wiring.
Appendices
MoTeC Appendices 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) In the Left Visual box, select Spectrogram 29
Appendices On the Tool menu click Control Right click in the screen to open the menu and select Spectrogram Click Properties to configure the spectrogram.
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.
Appendices Combustion chamber at TDC 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. 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.
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).
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. 3. 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.
MoTeC Notes 35
Notes
