Innovate Motorsports LM-1 Digital Air/Fuel Ratio (Lambda) Meter - Manual (Page 3)

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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. Stoichiometric for different fuels are as
follows:
Gasoline 14.7
LPG (Propane) 15.5
Methanol
6.4
Ethanol 9.0
CNG 17.2
Diesel 14.6
The measurement Lambda is the actual air fuel ratio over the stoichiometric ratio. A Lambda
measurement of “1” equates to the air fuel ratio of 14.7 (for gasoline engines). When Lambda is
less than 1 the engine runs “rich”, i.e., unburned fuel exists in the exhaust stream. If lambda is
greater than 1 the engine runs lean, i.e., free oxygen (0
2
) is present in the exhaust. 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. First Time Use
1. Verify that the included 9V battery is installed in the battery compartment on the bottom of the
instrument.
2. Connect the power cable to the LM-1 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. (The primary purpose for the
9V battery is to power the LM-1 when it is connected to a PC for data downloads). You must
have a 12V power supply available to power the oxygen sensor.
Note: The supply voltage to the LM-1 must not exceed 16V.
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: