Cat ECU's 348/355/Mondial T/F-40

Folks, I believe that technology has progressed enough to help us overcome the costs of the dreaded Cat ECU's by Vescovini. I found a $10 single chip thermocouple amplifies chip with the ability to produce a pull-up or pull-down signal based on the read temperature. It has a 0-1000 deg C range with a resolution of about 10mV/Deg c.

I am going to connect it to a relay which will split the pull-up signal to two outputs. I'm a motronic 2.5 so only need the one driving the dashboard warning light bulb, but the second output can be connected to the Motronic 2.7 pin to enable limp-home. Even more so it can be connected in a way to include a switch so if the user wants to override the limp-home mode they can.

It is a single chip solution, so there is no vulnerability to moisture. The total cost should be $50-75 or less per side with the necessary plugs fitted so to be plug and play.

I will publish the schematics so that if you want to build-test on your own you can...

I'll let you know of the outcome if there is any interest.

Marco

 

This is very, very interesting. Let us know how it turns out!

 

Huge possible find Marco - this will be interesting.

 

Marco seems to be a real whiz at electronics. Great to have you working on cheaper options, Marco!

 

Definately interested, as I'm running around right now with one ECU throwing random faults.

 

Count me in for the info and scematics!!!!

Pete

 

One is an all in K-Type amplifier/ADV for the BS2 integrated Circuit. One can remove the BS2 IC and lose the Digital output (for other tuning equipment. The single chip solution is the second one, based on the AD594/595. I have a suspicion it can only output a maximum of 5v, so can only monitor up to 500 deg. C and we need up to 725.

I'm speaking to the manufacturers to see if the +5V input is fixed at 5V or is able to use a range, meaning that with 10 - 12 V input it would be able to return up to 1000/1200 Deg C temperatures on the basis of 10mV/C.

Marco
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Good finding!
The data sheet says there is no problem to increase the power supply to 15V and extend the output range above 1250°C for a K type thermocouple (AD595).
A very simple power supply base on a 12V zener diode, some filtering and protection, and an adaptation of the scale factor to what the Motronic expects and it should work great.
If one day my cat ECUs fail .... thanks!
Image Unavailable, Please Login
Image Unavailable, Please Login

 

I ordered the connectors. I will make one in the next weeks. I will add a stabilized 12V power supply to it so the reference is constant. A standard volt meter set to a DC 20V scale will tell me the temperature, eg. a reading of 5.95 V is pretty much on 595 Deg C, thus linear.

If that works, the next part is to make a pull up trigger set to 6.5V and one at 7.25V. The 6.5V will trigger an intermittent solid state relay (flashing the slow-down) and the 7.5 will trigger a steady-on relay (wired in parallel to the switching one) for the constant on.

I will test them in parallel to the readings above (I never have recorded temperatures above 595 even on the track), but expect I will need to find a spot allowing me at least 5-6 minutes WOT to see if the tables are modified by the CO screw on the MAF (I have set it to a point 3 ohms just after the Oxygen sensor goes past stoichiometry at idle resulting in a 540 OHM setting) or if indeed they are pure tables set at the factory ignoring all pollution sensors.

To test the M2.7 output, I will just apply an 8 V DC current to the trigger circuit to test it. All it does is to send a 7V or more current to an ECU pin which is usually at 0.
I don't have the M2.7 as mine is a 2.5, which uses the human interface of a blinking light to tell the driver to take the foot off the accelerator ;-)

M

 

Update Marco?

 

Hi Marco,

Glad to have you on board and on our team. I have a Mondial T with a 2.5 Motronic. Let me know how I could help.

Thank you
Lino