ALM (Accurate Lambda Meter)

While most wideband controller manufacturers are still using LSU4.2 sensors for their flagship products, and only a few of them start to support "not-so-new" LSU4.9 sensors with their new wideband controllers, Ecotrons ALM has again taken the lead to release the most advanced wideband control system with Bosch's latest and greatest wideband O2 sensor: LSU ADV.

LSU ADV is the latest generation, on top of LSU4.9. Soon you may not see LSU4.2 sensors anymore. In fact, the only reason Bosch is making 4.2 sensors is because the aftermarket needs them. By combining both LSU4.9 and LSU4.9D sensors, Bosch has created the new gen, LSU ADV, which can be used for both gasoline and diesel engines. LSU ADV has been widely used by OEM applications. Soon it will completely replace the LSU4.9 sensors.

ALM is an air/fuel ratio (lambda) meter which uses a Bosch LSU wideband oxygen sensor and Bosch control chip CJ125 to accurately measure the exhaust air/fuel ratio (AFR) of variant combustion engines.

Click here, if you want to know immediately "What set ALM apart from other wideband controllers?"

All our ALMs have the high accuracy and fast response characteristics, which are the core of our design at the very beginning. First, ALM uses the more advanced LSU4.9 sensor, and recently LSU ADV, instead of the obsolete LSU4.2 sensor. LSU4.9 is the new generation wideband sensor. It is superior to LSU4.2. One obvious proof is: Bosch uses LSU4.9 across the board for their wideband applications. (See the appendix: LSU4.2 vs LSU4.9 for a quick comparison)
Click here to see why LSU 4.9 is superior to 4.2

Second, ALM uses Bosch chip CJ125 which is the integrated circuits (IC) specifically designed for LSU Sensors. With CJ125, all ALMs control the sensor temperature in the close loop mode and precisely keep the LSU4.9 sensor around 780 degree C. Note, Bosch's own wideband controller, "LambdaTronic, or LT4", uses the CJ125 driver chip.
Click here for Bosch LT4 wideband controller info
In fact, Bosch uses this chip wherever a LSU sensor is used. The CJ125 and LSU sensor are mated-pair by Bosch. Presumably LSU sensors work the best with CJ125 chips. Together, LSU 4.9 and CJ125 make our ALM a more accurate lambda meter in the market.

To meet different market need, we have developed our ALMs into the different packages.

The above picture shows the original ALM-s with a gauge.
It is mainly for motorsport applications, where a compact controller and a sleek gauge are preferred. ALM-s controller box has the size of 4"x2.6"x1", or similar to a business card size. It has a primary 0-5v linear analog output which can be used as the feedback control signal for an ECU. It also has the second analog output to a 52mm digital gauge. You can opt out our gauge and use a third party gauge which takes the 0-5v analog output.

Above is our CAN bus version, ALM-CAN.
CAN bus communication is the widely used data exchange method in the automotive industries. This is the professional way for automotive control systems, especially an engine control unit (ECU), to get the Lambda / O2 concentration from the wideband controller. CAN bus communication eliminates the DAC (Digital to Analog Converter) and then ADC (Analog to Digital Converter) conversions, and therefore eliminates 2 big error sources, and keeps the original signal accuracy. Compared to the CAN bus, 0-5V analog output is an amateur method.

Below is an OEM version of the ALM, ALM-board .
It is a mini-circuit board that can be easily built into any OEM controller. The board size is 2.5"X1"x0.5". It has its own LSU sensor connector, it gets the power from the main controller. It feeds back the Lambda or O2% to the main controller, either via 0-5V or CAN bus, or serial communication, at your option.

Below is another ALM version for lab environment, ALM-LED.
The big and high resolution LED display that is built in the controller box makes it a perfect instrument for dyno tuning. This one also has 0-5V analog or CAN bus option.

We now offer a wideband controller dedicated to diesel engines, ALM-LSU4.9D.
This is the only wideband controller you can find in the world that supports the LSU4.9D sensors. For years people have been wrongly told that LSU4.9 sensors are for diesel engines, and LSU4.2 sensors for gasoline sensors. And they don't know there is a diesel version the LSU4.9 sensor, LSU4.9D. Now we know LSU4.9 sensor is primarily for gasoline engines though it also works fine with a diesel engine. LSU4.9D is the one solely designed for diesel engines and it runs the best with regarding to the diesel soot environment. Below you can see the comparison of the 3 LSU sensors, click it you will find the meaning of the difference.

Here is a dual-channel version: ALM-II. It includes 2x LSU 4.9 sensors, driven by 2x Bosch CJ125 chips. It is typically used for V-shape engines, like V6, V8 or V10 engines, etc. It has all features of ALM, and more. It replaces ALM's LED display with a LCD and display more info: lambda or AFR, O2 concentrations in percentage (O2%), Analog inputs, etc.

Recently, we added a dual sensor version of ALM-CAN-II. This version of ALM uses the same CAN bus protocols, but supports 2 LSU4.9 sensors. It is suitable to run with a V6 or V8 engine, where the 2 banks of the engine requires 2x O2 sensors. This dual sensor wideband controller is the more cost effective solution for the V-shape engines. One stone, two birds.

For details of each version of ALM, click the below:
ALM-II dual-channel

List of ALM parts ( use ALM-Guage as an example, for other versions of ALM, click the pictures above )
Small ALM controller
52mm digital LED gauge (optional)
Harness (1.5 meter default, 3 meter optional)
Bosch LSU 4.9 sensor
Sensor plug and bung
Serial communication calbe
USB to serial converter (included)
Blue tooth for a Droid phone app (optional, not included, $50)
CD - documents and ALM GUI software

ALM technical specifications

Power supply
Input voltage range: DC 9V~15 V (12V Typical)
Input current: 50mA typical plus the heater current
Voltage protection : Reverse polarity protected, & overvoltage protected
Load Dump Clamp : Maximum voltage
Compatible: LSU4.9 (LSU 4.2 capable but not recommended)
Number of Sensors: One
Lambda range: λ = 0.55 ~ ∞ (Gasoline AFR: 8.08 to free air)
Lambda accuracy: ±0.008 @ λ=1.00
±0.01 @ λ=0.80
±0.05 @ λ=1.70
Air/Fuel Ratio: Fuel dependent (see lambda range and accuracy)
Free air calibration: No need (ALM measures the free air O2)
Response time
5ms updating rate (everything finished in 5ms)
0-5v analog output in 5ms updating rate;
CAN bus message in 10ms broadcasting rate
SCI message in 20ms broadcasting rate
Built-in close-loop control with CJ125
Real-time sensor temperature and heating duty cycle broadcasted on the CAN bus or SCI communication
Current Typical 1A; Max 1.7A
Heater return (H-): separate wire from Ground
Lambda analog output: 0~5V user programmable
Analog accuracy: ±0.005V error with a 10-bit DAC chip
Analog type: Reference ground to ECU
second Lambda analog output: 0~5V for a third party gauge, user programmable
advanced CAN bus communications (optional)
RS232 or USB (via an adaptor) for logging or programming
ALM Serial Communication Protocols - SCI/UART/RS232
User-friendly PC software for data acquisitions and analysis
ALMs broadcast: O2%, Lambda, Sensor temperature, heating duty cycle, and sensor error code
52mm digital gauge with numbers in the censor and bar-graph LEDs around
CPU: FreeScale 16-bit micro-processor S12P (auto industry rated)
Speed: 32MHz
Memory: 128k Flash, 6k Ram, 4k Data
Load Dump Clamp
Maximum voltage
Special features
On-Board-Diagnosis and error report
Self-learning of part-to-part variations, aging effect
Working with different types of fuels (gasoline, diesel, E85, etc)
Temperature range: -40C ~ +110 C (can be installed in the engine compartment)
Dimensions: 4" x 2.6" x 1"

Appendix:  LSU4.9 vs  LSU4.2

Characteristics LSU4.2 LSU4.9 Notes
lambda range lambda = 0.65 ~ ∞ lambda = 0.65 ~ ∞  
Accuracy only good at
lambda = 1 or moderate rich
accurate at
both rich and lean, wider range
LSU4.2 is only accuracy at lambda ≈1 and moderate rich, between 0.8~1.0 lambda; LSU4.9 has better accuracy in both rich and lean conditions, suitable for gasoline, diesel, CNG, etc.
Response time Slower Faster Thinner sensing element of LSU 4.9 makes it more responsive to the AFR change, dynamically more accurate, and easier to light off, less heating power needed.
Heating power 10W 7.5W LSU4.2 has the off-centered-heater vs. LSU 4.9 has the centered-heater in the laminate; LSU4.9 has better heating efficiency, less heating power needed.
Free air
needed not needed LSU4.2 is susceptible to reference air contaminations, which is called CSD (characteristic shift down), requires frequent free-air calibrations. LSU4.9 uses reference pump current instead of reference air. No more CSD. No requirement of free-air calibrations
Nernst cell
resistance vs. temperature
80~750C 30~790C LSU4.9 has higher resolution of internal resistance vs. temperature characteristics, which makes the temperature measurement more accurate, and better heater control, therefore higher accuracy of lambda.
Light off time long short LSU4.9 lights off faster. Lambda controls can be active much faster during warm up phase.
Reliability   Improved reliability LSU4.9 is superior to LSU4.2 with regard to the reliability and life.
Check with Bosch Still selling it Recommended Bosch recommends LSU4.9 to all OEMs.
Bosch uses LSU4.9 for its own wideband controller.

Download: Bosch LSU4.2 sensor tech info
Download: Bosch LSU4.9 sensor tech info

ALM-S without gauge @

$239 USD


ALM-S with a gauge @

$279 USD


Software and Documentation
Download documentation and software from here...

Our products are one month returnable, one year warranty!
Click here for Terms and Conditions...

We accept Paypal payment, and credit card payment!
Credit cards:
How to pay with your credit card without a Paypal account?