Sunday, February 12, 2017

Designing a better diesel tuning box - part 5 - tweaks and updates

Living close to a densely populated area means that it's hard to do consistent testing without spending a lot of fuel, which is also expensive.

Nevertheless, I took the pen&paper approach and started working my way from the basics.

I studied all the Bosch sensors from this page, used a bit of common sense and figured out that my sensor is a Bosch 0281002691, or similar, with a 180 MPa (26000 psi) nominal rating. This might be wrong but It's a good place to start.

I've already used Torque and my multimeter to get some data and it seems to fit with the sensor I've chosen. It might be wrong, but so far it clicks into place.

Using the data I've gathered I've created a simple JS page that shows some logs and tries to simulate what my module (and sensor) does:,output
(Note that this is the HTML/JS result after I did the interpolation.)

So the basic function is: the ECU commands the pump, this delivers a pressure, my module receives the sensor data (voltage), offsets it, outputs a new voltage to the ECU, the ECU processes it. I missed a step the last time: the ECU will receive the adjusted pressure, output a new pressure, the pump delivers, a new pressure is measured. This can cause oscillations within the engine, as the tuning module attempts to adjust for the new value.

Thursday, February 2, 2017

Automated coffee machine troubleshooting chart

My old post on the Saeco Talea Giro machine teardown (including deprecated one) has had tremendous success and I frequently get questions on how to fix this or that.

I am no specialist on this stuff but I've managed to keep my unit running after it was used in an office environment (>50000 coffees). So for me it's mostly guesswork and some logic, but I'll display this so that you can help figure out the problem with your own unit. I'll try to make this accessible to non-technical people, let me know if some idioms are too advanced.

I will try to update this guide with usual questions, but this is not a replacement for professional servicing.

Before troubleshooting make sure that the unit is cleaned and descaled and has enough water. Use the manual for this, each unit is different. Also, try turn the unit off and on, perhaps leaving it 1h undisturbed. This works around some of the bugs in software (firmware).
Learn the sounds of the machine and try to understand what it does in its normal state. There are several motors and they are easy to identify by sound.

Refer to my original post (from years ago) if you want to understand more about how such a unit is constructed: