Specifications

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4 Wire Wide Band Lambda Sensor
This technology takes advantage of the fact that a 4 Wire Wide Band Lambda sensor's voltage output is based on not only the oxygen differential between the exhaust
pipe and atmosphere, but also is dependant on the temperature of the sensor itself. Sensor impedance varies with temperature, so a MoTeC ECU measures not only Wide
Band Lambda Voltage, but also the sensor impedance. It is not possible to properly display lambdas without monitoring the sensor temperature. Systems which do not
use at least a 4 wire sensor typically have errors in displayed lambda as high as 8%!
5 Wire Wide Band Lambda Sensor
This newer technology is used to determine the air fuel ratio of an engine by measuring lambda sensor output and measuring the current required to hold the sensor
voltage output constant. An oxygen sensor produces voltage and a small amount of current as oxygen atoms pass across its substrate from high concentration to low
concentration. The greater the flow of oxygen, the greater the voltage produced. This is the case when a rich mixture is encountered. Conversely, when current is applied
to an oxygen sensor, oxygen atoms are moved from a low concentration to a high concentration or vice versa depending on the polarity of the current applied. The
MoTeC M400/600/800/880 ECU's are capable of measuring this type of sensor input which offers increased speed and accuracy over the older technology 4 wire
sensors. M4 and M48 ECU's can leverage the 5 wire technology by connecting a MoTeC PLM, which has a definable analog voltage output, to the Lambda input on the
ECU.
Bosch LSU and NTK UEGO Sensors
Both the MoTeC M400/600/800/880 and the MoTeC PLM are capable of operating with either the NTK UEGO or the Bosch LSU-4 5 wire wide band sensors. Of the
two, the NTK is most accurate. It is a true laboratory grade sensor. Its accuracy has been found to be about 1.5% better than that of the Bosch LSU. Additionally the
NTK has a better response time than does the LSU again about 1.5%. The NTK is the benchmark against which the LSU is measured. The advantage of the LSU sensor
is its lower price compared to the NTK. If you are doing very precise and accurate laboratory type testing, the NTK is the sensor for you. Both sensors have a life
expectancy of 500 hours on unleaded fuels and that number is diminished to 50 hours using leaded fuels. Lambda Sensors are very similar to spark plugs with respect to
their estimated life expectancy. Spark Plugs are designed to last 40,000 miles under optimum circumstances but they can be damaged in less than 1 mile by misuse. A
lambda sensor can be thought of the same way. Misuse by overly rich mixtures, high temperatures, overtightening or dropping can have a very negative effect on lambda
sensor life. Like spark plugs, lambda sensors cannot be returned under warranty.
What is Lambda?
Lambda describes an equivalence value in percentage of the chemically correct air-to-fuel ratio for any type of fuel. If the air fuel ratio measured in the exhaust pipe of
an engine is at the chemically correct (stoichiometric) ratio of air-to-fuel, lambda is equal to 1.0. In the case of gasoline, lambda 1.0 is equivalent to 14.7:1 air-to-fuel.
Lambdas less than 1.0 indicate the engine is running richer than stoichiometric, while lambdas greater than 1.0 indicate a lean mixture. If we measure a lambda value of
1.06 and we want a lambda value of .95, we simply increase the fuel delivered to the engine (pulsewidth) by 11 percent. This will place us exactly at .95 lambda. By using
the Lambda Was or the Quick Lambda functions a tuner can quickly shape the fuel table to match the engine's exact requirements. In addition, the W Lambda function
copies the Quick Lambda value to the sites immediately to the right and up above to help keep the fuel table variance from one site to another at a minimum.
Quick Lambda and Lambda Was
A MoTeC ECU, allows the user to define a lambda goal table based on load and rpm. The Quick Lambda function in the software allows a tuner to quickly adjust the
values in the fuel control table to achieve the goal lambda, based on the lambda reported by the sensor. If the reported lambda is .98 and the goal is .93, the ECU
automatically jumps to the current load site, and multiplies the value in the site by 1.05. The next time the engine runs in that site, the lambda will be .93. Similarly,
Lambda Was allows a user to locate a load and rpm site in the main fuel table and enter a recorded lambda measurement from a data log. The ECU multiplies the load site
value by the difference between entered lambda and the goal lambda value so that the engine will achieve the goal lambda the next time it runs on that load site. This
makes tuning much faster and easier than calculating the required enrichment based on an air fuel ratio number. Of course you can manually do multiplication, division,
addition and or subtraction on any site or a number of sites with only a few keystrokes, and the overall trim function allows you to trim the entire fuel or ignition table up
or down based on percentage.