I did get the new LSU 4.9 sensor I recently ordered working (bad connection to ALM-board). But EM3 still recording more and more frequent excursions to 480 (Lambda = 2) from the 171 (Lambda = 1) normal (EC3 numbers).

I realized that my ALM-board also has a serial output in addition to the 0-5V analog one I've been using.
Every 20mS it outputs Lambda and also the LSU 4.9 O2 sensor temperature (in deg C) (among other things).
I'm now reading that serial output into an Arduino Mega 2590 board with a data logging add-on. (Also reads EM3 and Dynon D100 EFIS serial outputs, displays trim tab positions and does other tings.)

For some reason I'm getting a rather noisy digital results (temp varying between -273C (0) and reasonable temps.
When the engine is not running the ALM-board maintains the 780C temp well (but also noisy digital signal).

Anyway, the interesting point is that I'm seeing temps as high as 1,026C (6,600 RPM burning 11.8 GPH  at 7,500 density altitude).

From the Bosch LSU 4.9 spec sheet: "Exhaust gas temperature: 930°C (1,030 for a short time)".
I have mine mounted about 8 to 10" from the 135 deg turn after the Renesis stock exhaust manifold. It appears I need to add an extension that moves it out of the exhaust stream?

The digital Lambda output tracks the analog output well, but erratic excursions on both [wrong!]. At this point I don't know if it's failure to properly capture the digital signal or  ALM-board, or LSU 4.9 failing. I had replaced my original LSU 4.9 a few hours ago.

Actually, looking at todays logged analog output from a 30 min flight, it is stable with no logged excursions (1 sec logging interval). Analog output from ALM-board goes to EC3 mixture input. Then from EC3 to EM3 data acquisition box  and from there to EM3 display unit (and its thumb-drive log) via serial link.  So (as I write this) I think I can rule out the LSU 4.9 and ALM-board and need to concentrate on the EM3. Seems the last several weeks work on data logging, etc.  have paid of :)

BTW I'm using a 14.2 factor to convert Lambda to ARF for 10% max ethanol regular pump gas.

Finn

On 7/16/2023 7:11 AM, Stephen Izett stephen.izett@gmail.com wrote:

Hi Finn

Thanks for the reminder of the details, so it sounds like I should power the controller ON as soon as the engine is running. 

Thanks  Finn.

On 16 Jul 2023, at 8:48 am, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

Hi Steve,

I reread the ALM board manual:
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I guess I missed the second part :)

So to keep it simple, maybe a relay powered by the oil pressure switch?
Or what input do you use for that for your CoPilot?

Finn

On 7/15/2023 12:55 AM, Stephen Izett stephen.izett@gmail.com wrote:

Hi Finn

Sounds like you use the same ALM board as me. All I recall is reading that you need a genuine Bosch, but not sure if that was simply sales talk.
I switch mine on manually a few moments after startup as per their instructions to avoid damaging the sensor.
I’m just in the process of building a micro I call CoPilot to manage a few things for me. One is the Wideband switch on after start.

Cheers

Steve Izett

On 15 Jul 2023, at 1:58 am, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

I now have about 100 engine hours on my Bosch LSU 4.9 wide band oxygen sensor with the Ecotron ALM-Board (0-5V output).

Recently I've seen the output intermittently  drop to 0 volts. So I replaced the sensor with one I bought on eBay a couple if years ago. (0258017025 WideBand O2 Oxygen Lambda Sensor LSU 4.9 for PLX UEGO AEM 30-2004 New).

Well, that doesn't work at all. The ALM-Board outputs zero volts all the time.

Anyone have experience with the Bosch LSU 4.9 oxygen sensor?

Are there versions with different pin-outs but same part number (0258017025)?

Finn


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