I once witnessed a mechanic advise a client to either repair or replace "brain box" ie ECU to solve excess fuel consumption. The client did scan his car and the faults registered are, no catalyst, air fuel meter (bank1 sensor1), coolant temperature too low (no thermostat), VVT etc. I don't know much about cars but found it hard to believe "brain box" could be the cause of excess fuel consumption. I could see the heavy deposit of black fumes in the exhaust pipe from afar. So I asked the mechanic why he gave such recommendation. His response was; "we have changed air fuel meter several times, checked the nozzles but the issue remains. the coolant was not replaced because of the age of the engine and distance covered so far (about 194k km) and we replaced the catalyst by constructing one at ladipo. I strongly believe the brain box is the culprit". I still have some doubts so I want the experts here to explain how ECU controls fuel consumption in a car.

What car model? Year....give details so that the experts will be able to assist you when they see the post.

2002 Camry LE. Should be a 2.4L

Cruise-z:
I once witnessed a mechanic advise a client to either repair or replace "brain box" ie ECU to solve excess fuel consumption. The client did scan his car and the faults registered are, no catalyst, air fuel meter (bank1 sensor1), coolant temperature too low (no thermostat), VVT etc. I don't know much about cars but found it hard to believe "brain box" could be the cause of excess fuel consumption. I could see the heavy deposit of black fumes in the exhaust pipe from afar. So I asked the mechanic why he gave such recommendation. His response was; "we have changed air fuel meter several times, checked the nozzles but the issue remains. the coolant was not replaced because of the age of the engine and distance covered so far (about 194k km) and we replaced the catalyst by constructing one at ladipo. I strongly believe the brain box is the culprit". I still have some doubts so I want the experts here to explain how ECU controls fuel consumption in a car.

Tell your client to run for his dear life from that clown.

From the result of the scan and the symptoms you mentioned, Let him check his oxygen sensor close to exhaust manifold. I would check the values from the sensor and the ECU before replacing the o2. All the same, he could as well as simply replace the o2 with a brand new one, not used one. A failed o2 would cause rich running and sometimes give black smoke symptom, like you observed.

As for the absence of thermostat, well, we have talked about it a lot. You will find related topics on the thermostat in the Car Talk Library. Note that absence of thermostat will increase fuel consumption as well, though shouldnt be the cause of the black smoke, but will contribute.

I hope the CTS (Coolant Temperature Sensor) is not faulty as well?

As for the VVT, i dont know much about it. Am yet to experienced vvt failure in my car, so i wouldnt know the symptom yet. Lets hope others can you on that.

Ikenna.

the mechanic is clueless..............runnnnnnnnnnnnnnnnnnn!!!!!!!!!!!!
the result of the scan is self explanatory...tackle those issues

Ikenna351:

Tell your client to run for his dear life from that clown.

From the result of the scan and the symptoms you mentioned, Let him check his oxygen sensor close to exhaust manifold. I would check the values from the sensor and the ECU before replacing the o2. All the same, he could as well as simply replace the o2 with a brand new one, not used one. A failed o2 would cause rich running and sometimes give black smoke symptom, like you observed.

As for the absence of thermostat, well, we have talked about it a lot. You will find related topics on the thermostat in the Car Talk Library. Note that absence of thermostat will increase fuel consumption as well, though shouldnt be the cause of the black smoke, but will contribute.

I hope the CTS (Coolant Temperature Sensor) is not faulty as well?

As for the VVT, i dont know much about it. Am yet to experienced vvt failure in my car, so i wouldnt know the symptom yet. Lets hope others can you on that.

Ikenna.

How can one tell if the coolant temperature is faulty?

Cruise-z:


How can one tell if the coolant temperature is faulty?

By measuring the resistance and volte values of the sensor, the CTS, with DMM (Digital Mulitimeter).

I dont know about Japs, but I know that Bosch CTS in my Lions would give 5 volts on the wire from ECU to the sensor (off the sensor). And would give 3 volts or less when plugged back on the sensor. I have forgotten the resistance value when tested. It has to be tested with the connector disconnected from the sensor. Test the sensor directly. Will check my workshop manual or car diary when i get home and post the resistance value to expect if still working.

Note that testing the volts values will need the ignition switch to be on (dont start the engine). And it has to be done in the morning before starting the engine (1st cold start) to get the best result or know how good the CTS still is.

Ikenna.

Ikenna351:

By measuring the resistance and volte values of the sensor, the CTS, with DMM (Digital Mulitimeter).

I dont know about Japs, but I know that Bosch CTS in my Lions would give 5 volts on the wire from ECU to the sensor (off the sensor). And would give 3 volts or less when plugged back on the sensor. I have forgotten the resistance value when tested. It has to be tested with the connector disconnected from the sensor. Test the sensor directly. Will check my workshop manual or car diary when i get home and post the resistance value to expect if still working.

Note that testing the volts values will need the ignition switch to be on (dont start the engine). And it has to be done in the morning before starting the engine (1st cold start) to get the best result or know how good the CTS still is.

Ikenna.

Thank you Ikenna. Are you based in Lagos?

Cruise-z:


Thank you Ikenna. Are you based in Lagos?

No, Abuja.


Ikenna.