VEMS Wideband & EGT Gauge
Wideband SensorImportant warning the Bosch LSU4 wideband is sensitive to excessive fuel:
DO NOT install the wideband sensor in your exhaust until you have got your engine running, initial start-up tests can cause a great deal of flooding or excessive fuelling which could potentially damage your sensor.
DO NOT leave the sensor left un-powered in the exhaust with the engine running, instead block off the sensor bung with either a threaded plug, or an old narrow band O2 sensor.
Install the sensor into your exhaust using a suitable bung. If your engine already has a lambda sensor you can replace it with your new wideband sensor, and use the Gauge's Lambda output. If you do not have a suitable (M18x1.5) bung please contact your supplier for fitting advice.
The sensor should ideally be mounted as close to vertical as possible in order to stop water collecting in the sensor during cold starting.
In order to make the installation easier, your Wideband gauge comes without the pins inserted in the 6-pin plug
- Make sure the purple locking plate is in the open position (Check the side of the plug).
- Pull the cable through the firewall if necessary.
- Insert pins in the correct position, using the diagram below. The pin numbers are on the back of the connector housing. Note that the pins will only slot into place if correctly aligned, do not force them into the plug.
- Make sure the purple locking plate is in the closed position.
Now connect the wideband sensor the 6-pin plug.
Exhaust Gas Temperature SensorThe Exhaust Gas Temperature (EGT) sensor is a K-type thermocouple it is important to note the wires colour and polarity of the wires. The green insulated wire is the positive (+) and white negative (-), it is vital that you ensure that the polarity is observed otherwise incorrect readings will result. The wire must be joined using correct K-type connector.
The sensor comes with a threaded bung to make fitting easier, it should be fitted into the exhaust manifold or turbo housing no more than 50cm from the exhaust port. With turbocharged engines you must fit your sensor before the turbine. The sensor tip should extend to the middle of the exhaust to get the best accuracy. It is vital to select the right type of sensor for your engine.
EGT Sensor typesThere are two types of sensor suitable for the two types of installation. The Normally Aspirated (NA) type is a 2mm diameter sesnor that is fast and responsive to the sudden snap temperature changes seen on a NA engine, but it's thin and will not withstand the extreme heat and vibration of a turbocharged engine.
The Turbo type sensor has a 6mm body to cope with heat and vibration and a 2mm tip to provide fast response.
Serial ConnectorIf you need to field program the unit or are planning on using the Datalogging facility you will need to connect your laptop or PC to the 9pin serial plug.
OperationEach time the module is powered-up it must first heat the sensor before it can display the correct Air Fuel Ratio, when it is doing this you will see an 'H' followed by an increasing value, this shows that the module is operating correctly. Once the sensor is upto its operating temperature the AFR is displayed, if the sensor is tested in fresh air the AFR will skip around 20.0 to 21.0. With the sensor Installed in the exhaust you will see a lower value, because the sooty residue will contain unburnt fuel.
Mode ButtonThe button on the front of the gauge display allows you to cycle through the 14 different display modes:
1. Lambda & Internal temp C, 2. AFR & Internal temp C, 3. Lambda & EGT C, 4. AFR & EGT C, 5. Lambda & Internal temp F, 6. AFR & Internal temp F, 7. Lambda & EGT F, 8. AFR & EGT F, 9. Lambda & MAT C, 10. AFR & MAT C, 11. Lambda & RPM, 12. AFR & RPM, 13. Lambda & MAT F, 14. AFR & MAT F.
Disk/Download ContentsOn this disk or downloaded file you will find:
- MegaLogViewer-Setup-v1.4.msi - Phil Tobin's MegaTune datalog output viewer, an invaluable tool for analysing your datalogs.
- MegaTune.bat - starts the MegaTune program which is used to display the gauge's outputs.
- readme.html - this file.
- UploadFirmware.bat - uploads the firmware to the Wideband & EGT Guage.
MegaTuneMegaTune provides us with: Real-time display generated by the VEMS Wideband & EGT Gauge, configuration of the gauge's additional functionality, and datalogging.
Click on the megatune.exe file in the MegaTune2.25 directory will load up the MegaTune application.
Field Programming New FirmwareYour Wideband & EGT Gauge will have been supplied with the latest firmware available at the time of purchase, VEMS systems are constantly in development, and while they're always fit for purpose you may want to use one of the newer features in the newer releases. The firmware is the industry term for the software that runs on your VEMS Wideband & EGT Gauge. Ensure that you've connected your laptop or PC to the unit with the 9pin serial plug, and then double click the UploadFirmware.bat file. If you have any problems with the upload please refer to the Fault finding section at the end of this document.
Extended FunctionalityTo use the extended functions of the VEMS Wideband & EGT gauge, all you need to do is a little extra wiring and set a few parameters in MegaTune.
Analog OutputVEMS Wideband & EGT gauge can produce a number of voltage outputs
- EGT linear output
- Narrow band output
- lp simulation
- Custom lambda curve
- 0 to 5V linear output
- Wideband scaled linear output
ConfigurationThe configuration of the Analog output is done using the Menu option Settings->Analog Output in MegaTune.
And setting the appropriate value in the Analog output (vout_conf) text box.
EGT linear output
vout_conf = 0
Intended for use with 3rd party datalogging systems, VEMS Wideband & EGT gauge this mode of operation provides a voltage scaled on the EGT value as described in this graph:
Narrow band output
vout_conf = 1
In this mode the VEMS Wideband & EGT gauge simulates the sensor voltage of the Bosch LSU11 narrow band lambda sensor:
vout_conf = 2
This mode is included and maintained for backward compatibility, if you don't already use it you don't need it.
Custom lambda curve
vout_conf = 4
The newer versions of firmware now provide the user with the ability to define a voltage curve to suit their specific requirements:
The curve is defined by the required voltage ouput across the lambda ranges: 0.7, 0.8, 0.9. 0.95, 0.98, 0.99, 1.0, 1.01, 1.02, 1.05, 1.1, 1.2, 1.4, & 1.7 Note the concentration of break points around Lambda 1 which provide greater accuracy at the important switching point. To specify the voltage that you require at these points multiply the target voltage by 51.
Using the graph above as an example, for the 4.1v @ 0.8 you would enter 209 in the output (0..255) for lambda = 0.8 text box.
0 to 5V linear outputvout_conf = 5
Wideband scaled linear outputvout_conf = 32 to 255
- Wideband 1V/Lambda - Enter 51
- Wideband 2V/Lambda - Enter 102
- Wideband 3V/Lambda (Motec default) - Enter 153
Connecting the RPM SignalUsing RPM allows you to provide a context to the information that you are datalogging.
Connecting An Analog SignalFurther context for your datalogs is obatained by feeding either the signal from your boost sensor for turbo/supercharged applications or throttle position sensor for normally aspirated.
Multifunction PlugThe additional functionality offered by VEMS Wideband & EGT gauge is obtained through the 15pin multifunction plug, and configuring the gauge's firmware through MegaTune.
- Pin-1: Lambda out (voltage output signal +)
- Pin-6: VBatt+ (12V)
- Pin-8: Analog input (Throttle, boost or pressure sensor. Max +5v)
- Pin-9: Lambda out ground
- Pin-10: RPM input
- Pin-11: RPM reference (input threshold can be adjusted; leave open)
- Pin-12: Boost solenoid output (or other power output) max 5A, flyback towards supply
- Pin-13, 14 & 15: GND connections
Serial PlugThe serial connector is a standard RS232 connector. It's primarily used by MegaTune to obtain the readings for its real time display, and is also used for field programming the gauge. The cable is a straight through connection
- Pin-2: Rx to Pin-2 on your Laptop or PC
- Pin-3: Tx to Pin-3 on your Laptop or PC
- Pin-5: Ground to Pin-5 on your Laptop or PC
Fault FindingGenerally we have had very few reported problems and the ease of connection and operation of the system means that there is very little fault finding information that we can provide. The VESM team pride ourselves on the level of support we offer, so in the case of problems please contact your reseller. Display does not show Check the 1Amp fuse, if that's intact make sure that the power feed to the gauge is okay. If you have lost the display after uploading newer firmware it may have become corrupted, so it is advisable to upload the firmware again.
Display flashes -E- This indicates that the gauge has reset, the most common cause is a poor grounding connection, or insufficient power. Try testing by connecting your gauge power cables directly to a good battery. Serial port errors You will not be able to upload new firmware, or use MegaTune If you have any programs running that access the serial port. Make sure that you disable any programs like Palm Pilot Synchronizer for the time that you want to use the serial port for VEMS operations
Errors Uploading Firmware The most common problem is that the serial port (COM) is not correctly set. To rectify this, open UploadFirmware.bat in Windows Notepad, or right-click UploadFirmware.bat and select Edit from the drop-down menu. The COM port is specified by the parameter -p COM1 change the number to the com port that you have the gague connected to.
MegaTune shows a MegaTune Open Error window If the first line in the window reads: The selected communication port (COMx) could not be opened. You need to first check the connection of the serial plug, if this is connected correctly then the problem may be due to MegaTune not being correctly configured. To set MegaTune to the correct serial port:
Select the correct port from the list, and click the 'Click to test' button to test the connection.