MoTeC Knock OKM User Manual
MoTeC SKM and OKM User Manual
Contents
Introduction ................................................................................ 2
Getting Started ........................................................................... 4
Installation .................................................................................. 5
SKM ......................................................................................................... 5
OKM ......................................................................................................... 5
Configuration ............................................................................. 6
Knock Detection....................................................................................... 6
Knock Module Configuration ................................................................... 8
Operation .................................................................................. 23
Appendices .............................................................................. 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 aluminium 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
SKM OKM
Inputs
Outputs
Physical
y Knock sensor input
y Knock window input
y Power supply 8 V
y Knock sensor out
y Audio
y Case size 38 x 90 x 25 mm
excluding connector
y Weight 100 grams
y 1 x 13 pin Autosport
connector
y Audio
y Fitted onto a M800 Plug-In
ECU
MoTeC Introduction 3
Other information
Compatibility
Related
software
Accessories
SKM OKM
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)
y M800 Plug-In ECUs
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
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 downloaded from the MoTeC
website at www.motec.com
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
• Operating System: Windows XP and up
• Audio and USB input
• Sound card capable of simultaneously recording and playing.
Alternatively, an external soundcard or third party device can be used.
. Further information on ECU Manager software
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
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
input rather than AV5.
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 signal
(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.
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
to occur, normally between 10 and 50 degrees
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
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 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
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.
The figure shows frequency based
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 significantly, 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
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.
y Select Function
y Type Function value 122 (Knock Window)
y Press ESC
y 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
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=5.000V)
Knock Gain Table
y On the Adjust menu click Functions
y Click Knock Control
y 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.
• On the Adjust menu click Data Logging Setup
• Click Knock Levels
• Select Knock Limit and type 10
• Select Knock 1 and type 50 (or greater)
• Continue the last step for all remaining cylinders in firing order
Follow the same procedure to log other useful channels.
Recommended channels are:
y Knock Retard Short Term for each cylinder
y Knock Retard Long Term for each cylinder
y 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 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 block 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
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