Yea, my dad used to fix it by himself haha. I am trying to repair all that kind of mechanics. I saw the ECU and it has the pin 23 for receiving the signal, but the big socket does not, i mean, there is no metal contact, just plastic.

Open loop means that the EHA thinks that the car is at max acceleration?

I would upload pics but there is no sunlight, tomorrow i will post them

Open loop means simply that the injection system is operating without any feedback of information about the mixture. Open loop operation occurs at all throttle positions and engine speeds. In open loop mode the mixture is determined by airflow deflecting the sensor plate and thus the fuel metering plunger in the FD. If the ECU and the EHA are operational, there could be some correction of mixture for temperature, barometric pressure, and also for rate of acceleration.

If you are able, examine the exhaust manifold and the exhaust pipe connected to the manifold for a place that an O2 sensor would be screwed into the manifold or pipe. The threads would be about 19mm. Although it is not impossible, it is difficult to understand that the car would have been constructed without feedback control.