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Many people ask us if our controllers work with Autronic ECUs, and in particular if the
Autotune function can be made to work.
The simple answer is yes (see below) but certain things should be done to maximise accuracy.
But first, lets dispell some myths that seem to have accumulated.
There are two Autronic Lambda meters, and they are described on the
Beninca website.
In the following extracts, we have added the blue italics.
- A Model: Uses a Bosch four wire broad band sensor (LSM-11) and has a air fuel ratio range of 9.0:1 to 36.0:1.
Update speed of readings is 0.5 of a second.
- B Model: Will use the Bosch sensor or a (NTK) UEGO 6 wire high speed sensor
(5 wire sensor + calibration resistor wire)
The high speed sensor will update every 0.10 of a second.
They also claim, of the UEGO sensor, that "it is also more accurate than the Bosch sensor".
The LSM-11 is not a wideband sensor, but a narrowband (NB) sensor with tighter tolerances than a normal NB sensor.
Of course the NTK UEGO will be more accurate. The Bosch LSU 5-wire (pump cell) sensor will also be more accurate than the Bosch LSM-11.
Perhaps Autronic's Bosch 4-wire and NTK UEGO sensor comparison is why people familiar with Autronic
think the Bosch LSU is less accurate than the NTK UEGO.
They are simply confusing the Bosch LSM-11 with the Bosch LSU sensors.
The fact is, comparing 5-wire sensors, the Bosch LSU is as good or better than the NTK UEGO.
As the Bosch LSU is usually considerably cheaper than the NTK UEGO, the comparison is even more favourable towards the Bosch LSU.
Because of the price difference - most people, it seems, buy the expensive Autronic Lambda meter but then
use the narrowband LSM-11 sensor.
This is total craziness! An expensive meter and an under performing 4-wire narrowband sensor.
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Issues in Using the 1 Volt Autronic Input
OK, you have a Tech Edge wideband controller with a differential 0-5 Volt output(*1).
How best to connect it to your Autronic ECU to use their Autotune function?
There are some issues to address, and we have solutions too:
- Autronic ECUs use a 0 to 1 volt input signal.
Tech Edge controllers provide a 0 to 5 Volt signal.
Although you can re-program the controller output to 0-1 Volt, it's better to
divide 0-5 Volts down to 0-1 Volts.
This improves the dynamic range by a factor of 5 and gives more precise, smaller steps.
- The Autronic default 10 to 30 AFR range (assuming AFR(stoich) = 14.7)
means just a quarter of this range,
from AFR = 10 to 15, is in the effective tuning range.
If we limit the AFR from 10 to 20, half the default, this gives us twice the dynamic range.
This and the previous item gives us 10 times the dynamic range of a simplistic approach.
The output setup is shown in the image at right - note the lower line sloping upwards; the leftmost
darker section is between 0 and 0.5 Volts, but you can see that over the 10 to 30 AFR range the
output (grey line) would go between 0 and 1 Volt.
- Electrical Noise is a fact of life in automotive applications.
Lambda sensor controllers precisely heat the sensor to high temperature using large currents
switched electronically. This can introduce noise in the ground return of the controller itself.
Most Tech Edge controllers have a WBlin+/- output (we call it a differential output) feature that's
designed to allow for small varying differences in ground voltages between the controller and the ECU.
Enabling this feature may require changing/removing a jumper inside the case of your controller
and then ensuring you connect both the WBlin+ and the WBlin-
connections to the ECU.
0→5 Volt & 10→20 AFR ⇒ 10:1 Resistive Divider
The best way to connect your Tech Edge unit to an Autronic ECU is with a 10:1 resistive divider.
We suggest you use 1% resistors of value 2k and 18k wired as shown at right.
Note that there are 4 connection points:
- specially programmed 0-5 Volts WBlin+ output from the Tech Edge wideband controller.
- Ground reference WBlin- input to counteract ground noise and voltage offsets.
- Divided Aut-in input to Autronic ECU - connect to 1 Volt oxygen sensor input.
- The Autronic ground point Aut-Gnd - either the oxygen sensor input GND point
or the ECU's analogue GND.
As well as the connection points two other things must be done to the Tech Edge controller
- Reprogram the WBlin output to go from and AFR of
10 to 20. note: range is not from 10 to 30..
The default range for Tech Edge units is from 9 to 19, so forgetting to reprogram
means the voltage will be close, but wrong everywhere!
- Remove the WBlin-GND jumper - refer to the documentation for your controller,
and to here for an explanation of why you must do this.
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Buy the pre-made 5 Volt to 1 Volt Adaptor
Although it's easy to make your own, we offer this pre-made adapter.
It has over 30cm (12") of cwire between the wideband unit and the Autronic unit.
There are four connection points just like the schematic shown above, and the image at right, the two BLACK wires are GND, the GREEN wire comes from the 0-5 Volt wideband output,
and the ORANGE wire goes to the Autronic 1 Volt input.
The shipped adapter comes covered in heat-shrink, so nothing shorts out.
(*) Notes
*1. The Tech Edge models 2A0 and 2A1 do not have a differential output. Other models do.
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