We all know that a racing engine has a mixture strength at which it will perform best. Normally this is adjusted on an engine Dyno and logged in the car to ensure that the target mixture strength is achieved and maintained. There are normally two different ways that the fuel mixture strength is expressed, Air Fuel Ratio (AFR) or Lambda ().
We shall be using Lambda in this discussion.
A Lambda value of 1 .00 is also known as the stoichiometric (4.7 Kilograms of air to 1 Kilogram of petrol).
A typical Touring Car, Normally aspirated GT Production Car or Formula 3 etc, would produce maximum power at between 0.89 and 0.9 Lambda. Leaner mixtures (i.e. higher numbers) would be used for light load running. The point being that, when optimum mixture strengths are determined for the specific engine and all its operating conditions, the objective is to always achieve and maintain these values.
Most of this task is performed by the ECU through the use of mapped compensations.

In a MoTeC M800, these take the form of compensations for -
Air box pressure
Battery voltage
Air box temperature
Exhaust back pressure
Fuel pressure
Two user definable compensations
Fuel temperature
Engine temperature

Although every amount of care may have been taken in the initial tune and setup, it is still pertinent to check the fuel mixtures at the track on the weekend of the racing.
If your ECU does not have the Wide Band Lambda function enabled you can, with the use of an Auxiliary Lambda Meter, input an analogue signal from the Meter to the ECU and log (if enabled) the results of mixture strength during your practice rounds. This will give you the information in order to make any minor tuning changes that may be required.
MoTeC’s new Professional Lambda Meter supersedes the gold box Air Fuel Ratio Meter. The Professional Lambda Meter (PLM) is less than 1 /3 the weight and size of its predecessor. It has the ability to be pre-programmed by the user via a RS 232 serial cable to a laptop. This allows things like the display to show Lambda, Air Fuel Ratio or Equivalence Ratio for any sensor com-patible fuel (Gasoline/Petrol, Alcohol, Gas, Diesel, or blend fuel as defined by the user). The resolution of the display (decimal points), display update rate, display filtering and backlight intensity may also be changed. The analogue output may be pre-defined as a linear or non linear output so as to be able to com-municate with a wide variety of other devices including the MoTeC ADL and ECU‘s.
The new type Bosch LSU and NTK UEGO sensors (as described in MoTeC News #4) are supported. These 5 wire sensors warm up faster and react to changes quicker. They also have the ability to be re-calibrated by the user as they age. Set up and used correctly the PLM can be a very powerful tool that can help you opti-mise your engines performance.