ALM-II (Accurate Lambda Meter with Dual Channels)

ALM-II front view
click to enlarge
ALM-II rear view
click to enlarge

ALM-II (Accurate Lambda Meter with Dual Channels) is the dual-channel version of ALM. It includes 2x LSU 4.9 sensors, driven by 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.

All connectors are upgraded to the industry rated, and the housing is aluminum, and rugged.

Real time measurement of O2 concentrations in the exhaust gas has become the new standard for a wideband controller. Only a few wideband controllers can do that.

Again, ALM-II can measure a wider range of lambda, especially between 1.5 to 3.0 lambda range. That's the key area for diesel, gaseous fuel, flex fuel, dual fuel engines. Only a few wideband controllers can do that, again.

Same as ALM, ALM-II uses Bosch LSU 4.9 sensors and CJ125 chips. 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

Besides air/fuel ratio measurement, ALM provides some supplemental functions which make your measurement or tuning more convenient: linear analog output to your ECU or gauge; LCD digital display; engine RPM probe, other analog sensor inputs like MAP and/or exhaust gas temperature (EGT); data logging with a serial communication to a PC, etc.

The accuracy and response time are the most important characteristics of the lambda meter, or any metering device.To show the accuracy and the fast response of ALM, we compare the ALM analog output to the analog outs of INNOVATE's LC-1 and LM2, which are claimed to be the leaders of the aftermarket wideband controllers.

Click here to see a customer application: using ALM as the lambda feedback device - real-time controls, not just steady-state!

Click here for all news from variant customer applications

List of ALM parts
ALM-II controller
Harness (1.5 meter default, 3 meter optional)
2x Bosch LSU 4.9 sensor
2x Sensor plug and bung
Serial communication calbe
USB to serial converter (optional, not included)
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
Polarity protection : Reverse polarity protected
Load Dump Clamp : Maximum voltage
Compatible: LSU4.9
Number of Sensors: dual LSU sensors optional)
Free air calibration: Not necessary
Lambda range: λ = 0.65 ~ ∞
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)
O2 consentration in %: critical for lean burn engines and gaseous engines, etc
Response time
5ms sampling rate
Control built-in PID 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
Narrow band O2 sensor simulated output (user programmable)
RPM input: Ignition pick-up
Analog input: MAP sensor optional
Analog input: EGT (exhaust gas temperature) sensor optional
RS232 or USB (via a converter)
User-friendly PC software for data acquisitions and analysis
Low cost LED digital display
Optional wideband gauge (52mm)
CPU: Freescale MC9S12P128 16-bit
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: -30C ~ 125C
Connector: multi-connectors, auto industry rated
Dimensions: 200mm X 120mm X 80mm

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 300~790C 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-II @ $599 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?