wideband controller ALM-Gauge

ALM (Accurate Lambda Meter)
ALM-S (Small Accurate Lambda Meter)

ALM (Accurate Lambda Meter) is an air/fuel ratio (lambda) meter which uses Bosch LSU 4.9 wideband oxygen sensor and Bosch driver chip CJ125 to accurately measure the exhaust air/fuel ratio (AFR) of variant combustion engines.

ALM-S is a smaller size version of our previous ALM . It has the same accuracy and fast response characteristics like ALM, but much smaller size. The 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 an analog signal output to the 52mm digital LED gauge. The gauge is optional, because some professional tuners already have a lot of gauges which include AFR display as a part.

Further more, it has the new feature of CAN bus communication as optional. This is a more advanced feature for professional engine controls where CAN bus is used widely and AFR signal can be broadcasted on the CAN bus.

Our ALM uses more advanced LSU4.9 sensor instead of LSU4.2 which is still used by most other wideband controllers. LSU4.9 is the new generation wideband sensor evolving from LSU4.2. It is superior to LSU4.2 with the obvious proof: Bosch uses LSU4.9 across the board for their wideband applications. (appendix: LSU4.9 vs LSU4.2)
Click here to see why LSU 4.9 is superior to 4.2

CJ125 is the driver chip specifically designed by Bosch for LSU 4.9/4.2 Sensors. Bosch's own wideband controller, "LambdaTronic", uses CJ125 driver chip. Actually Bosch uses this chip wherever the LSU sensors are used. They are mated-pair by Bosch. Presumably LSU sensors work the best with CJ125 chips.
Click here for Bosch LT4 wideband controller info with CJ125
Together, LSU 4.9 and CJ125 make our ALM a more accurate lambda meter in the automotive aftermarket.

Click here for our previous version of ALM and a lot of news on customer applications
Click here to see a successful story of an OEM multi-fuel engine application

List of ALM parts
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
Current Typical 1A; Max 1.5A
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
User-friendly PC software for data acquisition and analysis
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.

ALM-S without gauge @

$239 USD


ALM-S with a gauge @

$279 USD


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

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