MD Mustang Dynamometer User manual

LM-1 Digital Air/Fuel Ratio (Lambda) Meter
Manual
9/03/03
Warning!
The Oxygen Sensor used in this device gets very hot in operation.
Do not touch the hot sensor. Do not let a hot sensor touch a combustible surface.
Do not use the sensor with or near ammable liquids or gases. Failure to heed
these warnings may result in severe burns, explosions or res.
When installed in the exhaust, the oxygen sensor MUST be connected and
operating with the LM-1 whenever the car is running. An un-powered oxygen
sensor will be quickly damaged when exposed to hot exhaust gases.

Table of Contents
Table of Contents ............................................................................................................................ 2
1. Overview...................................................................................................................................... 3
2. The LM-1 Instrument ................................................................................................................... 3
2.1. The LM-1 Instrument (included)............................................................................................ 3
3. First Time Use ............................................................................................................................. 5
4. Installation.................................................................................................................................... 6
4.1 Mounting the sensor .............................................................................................................. 6
5. Operation ..................................................................................................................................... 7
6. Calibration.................................................................................................................................... 7
7. Recording other vehicle data with the LM-1................................................................................ 8
7.1 Overview ................................................................................................................................ 8
7.2 Recording............................................................................................................................... 8
8. Remote display of Lambda and/or AFR ...................................................................................... 8
8.1 Analog Lambda/AFR instrument............................................................................................ 8
8.2 Special considerations when installing LM-1 permanently in the vehicle.............................. 9
9. Programming the LM-1.............................................................................................................. 10
9.1 Installing the LM-1 Manager Software................................................................................. 10
9.2 Hooking up the LM-1 device to the computer...................................................................... 10
9.3 Resetting the calibration data ..............................................................................................11
9.4 Updating the software.......................................................................................................... 11
9.5 Changing the sensor type....................................................................................................12
9.6 Programming the analog outputs......................................................................................... 13
9.7 Downloading recorded data................................................................................................. 14
10. Tips, Tricks and Troubleshooting ............................................................................................18
10.1 General measurement requirements................................................................................. 18
10.2 Vehicles with ‘smog-pumps’ .............................................................................................. 18
10.3 Measuring at the tail-pipe .................................................................................................. 18
10.4 Single Cylinder Engines..................................................................................................... 18
10.5 Diesel Engines ................................................................................................................... 18
10.5 Reference cell or Pump cell circuit open or shorted errors ............................................... 18
10.6 Sensor Timing Errors......................................................................................................... 19
11 Advanced Topics ...................................................................................................................... 20
11.1 Connecting the LM-1 to simulate a narrow band oxygen sensor. ..................................... 20
11.2 Using a Serial Remote LCD Display.................................................................................. 21
Appendix A: LM-1 Accessories ..................................................................................................... 22
Appendix B: LM-1 Cable Pinouts .................................................................................................25
Appendix C: LM-1 error codes ..................................................................................................... 28
Appendix D: Limited Warranty...................................................................................................... 29
Revision History............................................................................................................................. 30
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1. Overview
The LM-1 is a hand-held instrument used to measure the Air/Fuel Ratio (AFR) or Lambda for an
engine. For gasoline-driven engines, the theoretically optimal air fuel ratio is 14.7 pounds of air
for every pound of fuel. At this ratio theoretically all available oxygen in the air combines with all
available fuel. This ratio is called the stoichiometric ratio.
The measurement Lambda is the actual air fuel ratio over the stoichiometric ratio. When Lambda
is less than 1 the engine runs rich. If lambda is greater than 1 the engine runs lean. Depending
on the engine, maximum power is typically delivered when the engine runs slightly rich (for
example at lambda values of 0.8 to 0.9 for most engines). This instrument provides a means to
measure the actual air fuel ratio or lambda in the engine in operation directly from the exhaust.
For this a special wide-band oxygen sensor is used to measure the lambda value derived from
the oxygen content (or lack thereof) of the exhaust gases.
2. The LM-1 Instrument
The LM-1 set contains the following parts:
2.1. The LM-1 Instrument (included)
Size: 7" x 4" x 1.5"
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2.2 Included cables and devices
Oxygen Sensor Sensor Cable
Power cable Serial Cable
Also included:
9V Battery
Bung/Plug set
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3. First Time Use
1. Install the included 9V battery in the battery compartment on the bottom of the instrument.
2. Connect the power cable to the 12V Power connector and plug the other end in your
cigarette lighter socket in your car. Note that the 9V battery is for powering the LM-1
electronics and display, but it cannot power the oxygen sensor. You must have a 12V power
supply available to power the oxygen sensor.
3. Do not connect the sensor yet.
4. Switch the meter on.
The display shows either:
when connected to 12V Power, or .
In the second case, switch the ignition of your car on.
5. Switch the meter off after 10 seconds.
6. Connect the sensor to the sensor interface connector. The sensor must be exposed to air for
the first time calibration.
7. Switch the meter on. The display should show now:
Indicating that the sensor is warming up to it's optimum operating temperature. The display
shows what percentage of the temperature is reached and what the battery voltage is that the
meter sees on the power connector. The warm-up period will last for about 30 seconds for a cold
sensor, depending on the sensor type used.
After the sensor is warmed up the meter automatically calibrates the sensor heater controller to
the particular sensor. During this 20-second period the LM-1 collects and calculates sensor
specific data required to quickly reach operating temperature in the future. After the first time use
the meter will use these values to regulate the sensor's temperature. During the heater calibration
the display will show:
Counting to 0. After that the display will show:
Note: When using the Bosch Sensors the LM-1 may perform multiple calibration passes. This is
normal and need not cause concern. When it completes, continue to step 8.
8. Press the Calibration button.
The meter will now calibrate itself by using air as a reference gas with a known oxygen content.
After the calibration period is over (2-3 seconds), the instrument is ready to operate.
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4. Installation
4.1 Mounting the sensor
On non-catalytic converter vehicle:
After the instrument is calibrated, and the vehicle's engine is warmed up, readings can be taken
from the engine’s exhaust. A probe clamp is required if the vehicle will be in motion (not just on
the dyno), and is recommended even when the vehicle is stationary. The oxygen sensor needs to
have the back part of the sensor (where the wires enter the sensor) exposed to outside air to
yield the most accurate results.
On catalytic converter equipped vehicles:
For those vehicles it is typically necessary to have a qualified muffler shop install a second
oxygen sensor bung upstream from the catalytic converter (included). The wide-band oxygen
sensor will be installed there. Plug the sensor bung when not in use (plug included). The sensor
must be installed in the exhaust pipe at the side or in the top.
Do NOT install it below the 3 o'clock or 9 o'clock position. Condensation
can form in the exhaust pipe and permanently damage the sensor.
On turbo charged vehicles:
Install the sensor downstream from the turbo before the catalytic converter. The high exhaust
pressure before the turbo interferes with the lambda measurement and the high exhaust
temperatures encountered there can damage the sensor.
Wide band oxygen sensors – like the one shipped with the LM-1 -- cannot
tolerate leaded gasoline and will be permanently damaged after a short period of
use. Do NOT use the LM-1 with engines that burn leaded gasoline.
WHEN INSTALLED IN THE EXHAUST, THE OXYGEN SENSOR
MUST BE CONNECTED AND OPERATING WITH THE LM-1
WHENEVER THE CAR IS RUNNING. UN UN-POWERED OXYGEN
SENSOR WILL BE QUICKLY DAMAGED WHEN EXPOSED TO HOT
EXHAUST GASES.
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5. Operation
Once the LM-1 has been installed and is in place (see Chapter 4: Installation), lambda
measurements can be taken.
In operation the meter's display shows:
Showing the current lambda value and air-fuel-ratio. The numeric lambda and air-fuel-ratio values
are averaged over about 0.2-0.3 seconds so that the numbers are more consistent and easy to
read.
If lambda is bigger than 6 (example free air), the display shows the oxygen content of the
measured gas instead of AFR.
The bar-graph at the bottom shows the actual instant lambda value in 16 steps. The more of the
bar showing, the richer the mixture. The bar at mid-level means a lambda value of 1.0 (AFR of
14.7 for gasoline). If the whole bar shows, the actual lambda value is 0.68 or richer (AFR of 10 or
less for gasoline). If none of the bar shows the lambda value is 1.32 or leaner (AFR 19.4 or more
for gasoline).
6. Calibration
To achieve maximum precision the LM-1 and its sensor needs to be recalibrated frequently.
When the measured lambda is bigger than 6, the display will show the oxygen content of the
measured gas in %. For free air it should show 20.9%. If the display value is different by more
than 0.6%, recalibrate. You can test the oxygen sensor by breathing on it. The oxygen content of
your breath will show.
The sensor MUST be operated in free air for calibration.
If the wide-band sensor is installed in a vehicle, wait 6-8 hours after running the engine so that all
exhaust gas is dissipated from the exhaust tract of the vehicle. Otherwise, disengage the oxygen
sensor and expose the sensor to air (away from the exhaust) for calibration purposes
1. Connect the meter to 12V from the vehicle and switch it on.
2. When the sensor is warmed up, quickly press and release the 'Calibrate' button.
3. After the calibration is complete, switch the LM-1 off and wait for 30 seconds before you start
the car.
The display will show "Free Air Calibr." while it calibrates itself. When the calibration procedure is
finished (2-3 seconds) the display returns to normal showing lambda and oxygen content. If the
oxygen content now differs from 20.9% by more than 0.6%, repeat the calibration.
When the sensor is changed – either with a replacement sensor or a new type of sensor --, the
heater circuit of the LM-1 needs to be recalibrated as well. Follow the steps in chapter 3 'First
Time use'. The heater calibration data in the LM-1 will be reset when the meter is operated from
12V without a sensor connected for at least 2 seconds.
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7. Recording other vehicle data with the LM-1
7.1 Overview
The LM-1 has the capability to record other vehicle data from other vehicle sensors while driving
so as to compile a complete log of engine data. The AUX input connector of the LM-1 allows
connecting up to 5 other sensors to the LM-1 whose data values will be recorded. The optional
AUX sensor cable for the LM-1 plugs into the side of the LM-1 instrument and has 5 clips to hook
up to the other sensors.
Never connect the Aux inputs to 12 volt or battery power. Connecting the
inputs to sources that generate greater than 5 volts will result in damage to the
LM-1.
The LM-1 simply records the voltage on each input connection with a resolution of 10 bits (a
precision of 0.00488 Volt). LM-1 will record up to 44 minutes of data from all sensors including
lambda. A new value for each sensor is recorded every 0.08125 seconds (roughly 12
times/second). The recorded data can be later downloaded into a Microsoft Excel spreadsheet or
graphed and analyzed by the included software. To download the recorded data into an Excel
spreadsheet see chapter 9.7, 'Downloading recorded data'. Software to view and analyze
recorded data log files can be downloaded at www.mustangdyne.com
7.2 Recording
To record data in the LM-1, press the 'Record' button. The LM-1 will show on its display a
blinking 'R' between the lambda and AFR/O2 display while recording. To stop recording, press
the 'Record' button again. Each time you start recording a new record ‘Session’ is created. A
total of 44 minutes of data can be recorded in the LM-1. If the internal memory of the LM-1 is full,
the blinking 'R' will not show when starting a recording session. Instead it will show an 'F' for 'Full'
for a few seconds. To erase all recorded data, press and hold the 'Record' until 'FR' (for flash
reset) shows between lambda and AFR/O2 display. To download the recorded data into an
Excel spreadsheet see chapter 9.7, 'Downloading recorded data'. Software to view and analyze
recorded data log files can be downloaded at www.mustangdyne.com
8. Remote display of Lambda and/or AFR
In some applications it may be desirable to mount the LM-1 in the engine compartment or under
the dash permanently and monitor the air-fuel data remotely using a dash-mounted instrument.
The LM-1 provides two options for that application.
8.1 Analog Lambda/AFR instrument.
There are many analog lambda/AFR displays on the market. They are essentially voltmeters for a
voltage between 0 and 1 V and measure the analog voltage of a narrow band oxygen sensor.
Some are true analog instruments while others provide a LED bar. Because of the very limited
sensing range of a narrow band sensor they are essentially useless as true AFR meters. LM-1
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allows these instruments to be used as true remote AFR or lambda meters. Connecting these
meters to the second analog output of the LM-1 allows to use them as true remote AFR meters,
provided the LM-1 analog output is programmed to the characteristics of the used meter.
The LM-1's second analog output is factory programmed to provide a linear output between 1V
and 2V for an AFR of 10 to 20, allowing using a digital voltmeter as AFR display. Any other linear
output range between 0 and 5V can be programmed. See chapter 9.6, 'Programming analog
outputs' for details.
8.2 Special considerations when installing LM-1 permanently in the vehicle
Do NOT install the 9V battery in the LM-1 when installing it permanently in
the vehicle.
In a typical permanent installation the LM-1 will be powered by switched 12V from the vehicle
(12V switched on when the ignition key is turned on) while its power switch is permanently on.
Because LM-1 automatically switches to internal battery power when it does not detect 12V, the
internal battery would drain quickly while the vehicle is parked. To avoid this, do not install the 9V
battery. The LM-1 will function correctly without it and will be able to record as usual. To
download recorded data, follow the alternate steps described in chapter 9.
It is NOT a good idea to connect the LM-1 permanently to 12V and switch it on before the vehicle
is started. The sensor would heat up to its operating temperature. Depending on the climate and
the senor position in the exhaust, condensation water can form in the exhaust pipes. This
condensation water could then be blown by the exhaust stream against the hot sensor when the
car is started. The resulting heat shock can permanently damage the sensor.
To further protect the LM-1 when installed permanently it is a good idea to power it up only after
the car is started. The starter motor in some vehicles can create voltage spikes of over 100V that
have the potential to do damage. Although rare, this is a real possibility and the LM-1 contains
protection circuitry to guard against it. A relay connected as shown below insures that the LM-1 is
disconnected while cranking. This reduces further drain on the car battery by the sensor heater
and protects the LM-1 against abnormally large voltage spikes.
Connect one terminal of the relay switch and relay coil to switched 12V (number 15 on European
cars). Connect the other switch terminal to the 12V input of the LM-1. Connect the other end of
the relay coil to the starter solenoid wire (number 50 on European cars). When the starter
solenoid is operated, the relay will switch off. In running condition the relay coil current will flow
from 12V through the starter solenoid to ground. The relay coil current is normally far too small to
operate the starter solenoid.
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9. Programming the LM-1
The LM-1 is programmable with the following functionality:
1. Change the relationship between Lambda and AFR.
2. Upgrade and change the software.
3. Switch between sensor types.
4. Change the output characteristics of the Analog outputs.
5. Download recorded data into a spreadsheet.
6. Graph and analyze the recorded data.
9.1 Installing the LM-1 Manager Software
Put the included CD in your CD-drive on your computer and follow the instructions on screen.
The LM-1 Software will be installed including pre-set directories for log-data and download
software.
The LM-1 Installer also puts entries for the LM-1 Software in the Start-Menu of your computer
under the heading ‘Innovate!’.
Two version of the Software will be installed:
1. LM1 Manager Demo
2. LM1 Manager
The difference between the versions is that the Demo Version does not require the LM-1 to be
hooked up to the computer via a serial port. It simulates a connected LM-1 instrument.
9.2 Hooking up the LM-1 device to the computer
- Connect the included serial download cable to a free serial port on your computer.
- Connect the round Mini-DIN8 connector to the serial port of the LM-1.
- Start the LM-1 Manager
- Switch on the LM-1 Instrument.
The LM-1 display shows:
The LM-1 will stay in serial mode until it is switched off, either by its power switch or by
disconnecting 12V if no internal battery is installed.
Your screen should look like this:
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On this page you can see the software version of the LM-1, which sensor your LM-1 uses and
you can change the multiplier to calculate AFR from Lambda. A number of different multipliers
are already pre-selectable but you can change it to a custom one for the particular fuel you are
using.
9.3 Resetting the calibration data
Press the Reset Calibration button if you want to reset all calibration data in the LM-1.
This will clear all calibration data of the LM-1.
9.4 Updating the software
Click the 'Update Software' in the main page. Update software for the LM-1 has the extension dld.
You can download the latest LM-1 software from the Mustang Dynamometer web-site at
www.mustangdyne.com
If your computer crashes during a download, the LM-1 has a recovery mechanism where it will be
able to retry the download again and not be disabled by half loaded software. Switch the LM-1 off
and on again and then try to restart the LM1 Manager software. The recovery mechanism is
designed to be able to recover 99.9% of the time. While we don’t anticipate this occurring, it is
possible that the LM-1 will not recover correctly and may need to be serviced at our factory. If you
suspect this is the case, contact Mustang support.
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9.5 Changing the sensor type
The LM-1 device is compatible with the following sensors:
Device Name OEM Part Number
Bosch LSU 4.2 0 258 007 057/058
Bosch LSU 4 0 258 006 066
NTK L1H1 L1H1
To switch a LM-1 to a different sensor type, follow these steps:
1. Select the sensor type to use in the Info/Set AFR Tab of the LM1 Manager and let the LM1
Manager download the appropriate software into the LM-1
2. Disconnect all cables from the LM-1 and remove the 9V battery.
3. Open the LM-1 housing by removing the 4 screws holding the housing bottom to the housing
top.
4. Carefully separate the two housing parts. Be careful not to stretch and break the battery cable.
5. On the main circuit board in the top housing part, locate the 8 pin sensor selection header.
6. Move the jumper to the appropriate position for your new sensor. See picture below.
The jumper in this picture is shown installed for the NTK L1H1 sensor.
The second position from the bottom is for the BOSCH LSU4.2 and LSU 4 sensor.
The remaining two positions are reserved for future sensors.
7. Reassemble the LM-1, reinstall all cables and the 9V battery if desired.
8. Follow the steps in Chapter 3: First Time Use .
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9.6 Programming the analog outputs
Select one of the Analog output tabs. The Analog output page looks like this:
This shows the analog output voltages versus Lambda for one of the two analog outputs. The
graph display is automatically scaled to the selected voltages. For each output you can specify a
minimum and maximum lambda value and the associated voltages. Below the minimum and
above the maximum lambda values the output voltages stay constant at the associated
programmed voltage.
By selecting the ‘use Air-Fuel-Ratio’ button you can program the curve by AFR instead of
Lambda.
Click the Program button to download the new data into the LM-1.
As factory programmed the first output simulates a typical narrow band oxygen sensor. The
second output is programmed to output between 1.0 V for an AFR of 10 (gasoline) and 2.0V for
an AFR of 20. This allows to connect it to a digital voltmeter or panel meter (0..2V input) to show
directly AFR. Other curves of course are easily programmable
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9.7 Downloading recorded data
Select the 'Data Logger' tab.
The download page appears:
This display is organized in 6 columns.
The two rightmost columns are used only if you hooked up the optional LM-1 Aux expander
module. See details how to use them in the LM-1 Aux expander manual.
The column from left to right:
1. Input trace color.
The Inputs are color coded on the AUX input cable. The same color is also used in the traces
for the data graph described below.
2. Input Name
Each Input can be renamed into a meaningful name (like TPS, MAP, MAF, CT, IAT) and so
on.
3. Import Unit
When checked, the input data is imported as voltage (0-5V) or as sample data (0..1023).
Right click on the check mark to customize the interpretation of the input data. The
customization dialog box allows you to set the unit value to use (for example pound/min for a
MAF sensor), the minimum value the sensor puts out at what voltage and the Maximum
value the sensor puts out. See below:
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The scale will be automatically expanded to a 0-5V scale. Clicking the check mark in this
column switches the input back to either voltage or sample data mode.
4. Input in Use
Check the button if this input is actually hooked up. The LM-1 will record from each input
regardless if the input is actually connected to something or not. If it is not used, this check
mark allows you to prevent it to be included in the graph, printout or in the saved data file.
9.7.1 Loading and Saving Log Data
Click the ‘Load’ button to either download LM-1 Log data or re-load a previously recorded log file.
The log file data format is compatible with the DIF file format that most spreadsheet programs are
compatible with. Each log data file starts with a header that describes the usage of the inputs. To
save log data from the LM-1, press the ‘Save’ button.
9.7.2 Importing Input Descriptions.
As a convenience the input settings from a previously saved log file can be quickly re-loaded using
the ‘Import Input Descriptions’ button. This saves you from re-entering all the input settings.
9.7.4 Resetting the log in the LM-1.
This button is grayed out if no log data is present in the LM-1. Pressing it clears the log data in the
LM-1 unit.
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9.7.5 Graphing the log data.
Click the ‘Show’ button. The log data will be shown as graph as in the following display:
Select the vertical scale for the input of interest by clicking on the appropriate input selection
button in the lower left hand corner of the graph window. You can hide or show a trace by right-
clicking on the appropriate input selection button.
Change the time scale by pressing the buttons.
Change the vertical scale of the vertical scaling of the selected input by pressing the or
buttons.
If there is more data that can be shown on the screen you can scroll it into view using the
scrollbars or by dragging the graph. If a portion of the trace is either above or below the window
you can quickly scroll it into view by right-clicking at the appropriate time in the graph in which you
are interested.
Right click on the vertical scale to quickly switch between inputs of interest.
The measurement icon above the graph can be moved anywhere within the graph window to
exactly measure the different inputs at the selected point in time.
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9.7.6 Printing the log data graph.
To print a graph press the button. The printer dialog appears:
This dialog is divided into four sections:
In the ‘Printer’ section select the printer to use. Usually you do not need to touch this section.
The ‘Print range’ section allows you to select the time range you want to print.
The ‘Presentation’ section allows you to select if you want to show the time-scale or vertical scales
for each input expanded as in the window or at their normal scale.
Check the ‘Print Black and White only’ button if you do not print on a color printer.
The ‘Show vertical scales’ section allows you to select if you want to show the vertical scale on the
left of the graph on every page or only on the first one, or if you want to show the scales for all
traces or only for the input-of-interest trace. The input-of-interest trace (the one currently selected
in the graph display) will always be shown next to the graph and the grid-lines represent divisions
of that trace.
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10. Tips, Tricks and Troubleshooting
10.1 General measurement requirements
The LM-1 measures the air-fuel-ratio by measuring the amount of oxygen in the exhaust for lean
conditions or the amount of unburned or partially burned fuel for rich conditions. An exhaust leak
will allow oxygen to enter the exhaust stream and therefore will measure leaner than the engine
is actually running. For correct measurement, air-leaks in the exhaust MUST be prevented under
all circumstances.
Missing ignitions where the air-fuel mixture does not light up also pump unburned oxygen into the
exhaust and cause the LM-1 to measure lean.
The only circumstance where the LM-1 will measure richer than the engine is running is if the
pressure in the exhaust tract is excessive and the engine is running on the rich side.
10.2 Vehicles with ‘smog-pumps’
Older fuel injected vehicles with a ‘smog-pump’ actually inject air in the exhaust stream to aid
their catalytic converter in the burn-up of unburned or partially burned fuels. This additional air will
make the exhaust look leaner than the engine is running. To accurately measure, install the LM-1
sensor up-stream of the outputs of the smog-pump. If this is not possible, temporarily disable the
smog-pump by removing its drive belt.
10.3 Measuring at the tail-pipe
On non-catalytic converter equipped vehicles it is possible to measure the air-fuel-ratio at the tail-
pipe. It is highly recommended to use the optional LM-1 Exhaust Clamp. Without it too much
outside air may enter the exhaust, especially at idle, to prevent correct measurements and
leading to a lean measurement. Sticking the sensor itself into the exhaust pipe can yield
inconsistent results because the sensor will not have outside air available as a reference gas and
its reaction time becomes so slow that the LM-1 will report a sensor timing error. The oxygen
sensor needs to have the back part of the sensor (where the wires enter the sensor) exposed to
outside air.
10.4 Single Cylinder Engines
These kinds of engines are difficult to measure at the tail-pipe. The oscillations of the exhaust
gas are so large that a lot of outside air enters the exhaust and prevents correct measurement.
Sometimes it helps to just wrap a piece of heat resistant cloth around the exhaust clamp to
prevent outside air from entering the exhaust.
10.5 Diesel Engines
Diesel Engines and gas turbines run at wide open throttle at all times. They do not have a throttle
but regulate power by the amount of injected fuel. The LM-1 can still be used, but measurements
at idle will read as lean.
10.5 Reference cell or Pump cell circuit open or shorted errors
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Under some rare circumstances it is possible that the heater calibration data in the LM-1 is
partially destroyed. This can manifest in the above-mentioned errors. Follow the steps in chapter
3 ‘First time use’ to reset the heater calibration data.
10.6 Sensor Timing Errors
These errors are typically encountered when the sensor does not have outside air available as
reference gas. If you encounter this error, restart the LM-1 and operate the sensor in free air. If
you still encounter this error, the sensor may be bad and needs to be replaced.
Replacement sensors are available from your nearest VW dealer under the VW part-number
021-906-262-B
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11 Advanced Topics
11.1 Connecting the LM-1 to simulate a narrow band oxygen sensor.
It is possible to install the wide-band sensor in place of the OEM oxygen sensor. In this case the
meter's analog output signal will replace the OEM oxygen sensor's signal to the fuel injection
computer. EFI equipped cars typically incorporate a narrow band oxygen sensor. These sensors
are typically 1, 2, 3 or 4 wire sensors.
The analog output connector of the LM-1 can simulate the operation of a narrow band sensor
while the wide-band oxygen sensor is installed in place of the OEM narrow-band sensor.
Factory equipped Analog output 1 of the LM-1 is programmed to simulate a narrow band sensor.
Some vehicles are equipped with oxygen sensors that do not produce an output voltage but
change their resistance depending on exhaust gas content. These sensors cannot be simulated.
They are used in less than 1% of all vehicles. Refer to your vehicles specifications if you think
that your vehicle may be in this category. The same is true for vehicles already factory equipped
with a wide-band oxygen sensor. They cannot be simulated.
Some EFI-computers will create a fault when the heater power wires of the oxygen sensor are
disconnected. In this case mount the old oxygen sensor in a safe place (but not necessarily in the
exhaust) and connect the heater wires to it to keep the EFI-computer happy.
Be careful where you mount the stock sensor, as heated sensors will get
hot.
To connect the LM-1 to the EFI-computer, first determine what kind of narrow band sensor is
used, then follow the instructions below (requires a digital multimeter to determine correct OEM
sensor wires):
a. Vehicle has a 1-wire sensor:
Wire analog output 1 directly to the wire.
b. Vehicle has a 2-wire sensor:
While the engine is off determine which of the 2 wires has a low resistance between the wire and
the sensor body. This is the heater power for the sensor. Wire analog output 1 directly to the
other wire. Leave the heater power wire unconnected but make sure it cannot ground itself or see
above.
c. Vehicle has a 3-wire sensor:
Typically the 3 wires are heater power, Ground and sensor element connection.
Generally they have 1 black wire and 2 white wires. Connect the black wire from the EFI
computer to analog output 1 of the meter. Leave the other wires unconnected but make sure they
cannot contact any metal parts or see above. If the wiring colors are different, then heater power
can simply be determined by measuring the voltage on the wires when the engine is running. The
wire showing 12V or more is the heater power. The sensor element connection voltage fluctuates
around 0.45V when the car is warmed up. Wire analog output 1 directly to this wire. The Ground
connection has low resistance to chassis ground (less than 1 Ohm). Measure while the engine is
off.
d. Vehicle has a 4-wire sensor
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