Mazda Allegro Motor 1.3 MT Distributor

Hello people !!

I hope you are well, I am Alfredo Quotes, I live in Colombia and I am an electronic engineer and I would like to put to its consideration a problem of operation of a Mazda Allegro Model 2003, 1.3 engine, manual transmission. In advance I appreciate your help.

DESCRIPTION OF THE FAILURE:
When the vehicle turned on, the motor temperature control electro-speaker (not the A/C), the injection pulses increased double and therefore the autonomy of gallons/liters per kilometer was reduced by half, presents jaloneos or trepidation when driving at low RPM in 1st and 2nd march.

What I have reviewed:
- ECM scan and have a code per ECT (temperature sensor).
- Validate the status of the lines (2) and measured respectively ref (5V) and mass.
- Change the Ect sensor, and deleted the fault code (it does not erase because the fault persists).
- Valid possible false contacts in the connectors and adjust the pins.
- I validated the electro-ventilator relay (this OK).
- Validate the electro-ventilator circuit.
- I tried another new temperature sensor and is not corrected.

If someone has or had a similar failure, I would appreciate that they could guide me about anything else to be able to check, if any of you has the Mazda Allegro manual in Spanish of the 1.3 Socch engine with a distributor, I would thank you if you can share it to me.

Thank you!

AMFR

Hi Alfredo. The failure you describe is typical of an electronic control module that does not have the engine temperature signal or this is very different from that of the air. Not having certainty of the actual temperature of the engine coolant, lights the electro -ventilator, commanding the relay to close (avoid engine overheating)
Now I see that you measure the 5V and mass reference well. Now you must be careful with the themist used by Ford and Mazda, they are in many cases of positive coefficient or PTC. That is, the thermistor resistance rises with the increase in temperature and does not fall as in the NTC themers used by the vast majority of engineers designers of modern electronic control systems.
I recommend measuring the voltage drop with the circuit running, both in the signal line and in the mass, ideally with an oscillograph. You can have a thermistor or temperature sensor changed, which does not correspond to the one that uses your car.
The other, much less likely, is the spoiled control module, you already know an analog signal, must enter the ECU, filter and/or amplify, then digitize. The ECU Motor only processes digital signals ... If the signal enters the ECU Motor and by the scanner you do not resibe the temperature data or it has a subtituto value of -40 degrees (hence the widening of the imjection pulse can be. Test the above and how many. Greetings from Chile.