there's a lot speculation about coolant temperature sensor sending signal to CPU , CPU commands the air/fuel sensor to minimize air/fuel ratio sent to the injectors to spray less fuel(close loop) or else keep running rich (open loop) and also the O2 sensor in the exust monitoring excess oxygen in the exust so that the air/fuel sensor to keep minimizing air ratio at different times during higher reving and idle for a better fuel consumption or economy, it all starts up with themostat regulating engine temperature to 100 degree

I know engine oil performance is one of the reasons why 100 degree engine temperature is needed

my question is

1) does open loop and close fuel regulations really exist?

2) if yes , must the coolant temperature reach 100 degree to activate the close loop operation (less fuel) ? as to avoid the issues of flooding the celinder with excess fuel which may course excess carbon deposit , engine oil contamination and catalyst converter damages if themostat is bypassed

3) what deference between o2 sensor and air/fuel sensor


I need answers base on experience and experiment

timenamoney:
there's a lot speculation about coolant temperature sensor sending signal to CPU , CPU commands the air/fuel sensor to minimize air/fuel ratio sent to the injectors to spray less fuel(close loop) or else keep running rich (open loop) and also the O2 sensor in the exust monitoring excess oxygen in the exust so that the air/fuel sensor to keep minimizing air ratio at different times during higher reving and idle for a better fuel consumption or economy, it all starts up with themostat regulating engine temperature to 100 degree

I know engine oil performance is one of the reasons why 100 degree engine temperature is needed , but when using unrecommended engine oil weight like 20w50 instead of 5w30, 20w is ok for Nigeria climate at startup then 100 degree at full warm up will make the oil 50w too thick and course internal issues which means this case 100 degree temperature is not needed and can bee avoided by removing the themostat with a 50/50 coolant and distilled water so that it hardly reach 60 degree then oil weight may flow like 30w or 35w instead of 50w, as a short cut

my question is

1) does open loop and close fuel regulations really exist?

2) if yes , must the coolant temperature reach 100 degree to activate the close loop operation (less fuel) ? (as to avoid the issues of flooding the celinder with excess fuel which may course excess carbon deposit , engine oil contamination and catalyst converter damages) if themostat is bypassed

I need answers base on experience and experiment

You are mixing up things

1 at cold temperature eg in the morning lets say at idle the rev goes up a bit (add more fuel) this to make the engine reach operating temperature very quickly so yes the temperature sensor send signal to ECU to calculate how much to fuel to add but i wouldnt say its an open and close loop because its constantly monitored and changing based on other monitoring sensors

2 the 90-100 degrees doesnt activate your (open loop) the 90 degrees is the best operating temperature for a car which gives you the best performance and efficiency from both fuel per mpgs to also best effective oil temperature though new oil nowadays are multiple grades which at low temperature and high temperature it still give you the same protection

Running your car at below 80 degrees (removing thermostat) thats where you increase carbon deposit as the fuel is being burnt below the most effective operating temperature which is 90 degrees, as along the ECU is getting engine temperature reading that is below 80 degrees the ECU will increase the air fuel ration because it should get back a 90 degrees signal from the temperature sensor therefore you damage you catalystic converter very quickly

So if the engine operating temperature reaches 90 degrees, the ECU will trim the ration becoz the operating temperature has been reached, all people who driving their cars with no thermostat are actuall running rich and the ECU is adding more fuel to help in increasing the temperature to its operating temperature of which it will never happen becoz the coolant is not being allowed to reach 90 degrees becoz its being constantly being cooled

ZIMDRILL:


You are mixing up things

1 at cold temperature eg in the morning lets say at idle the rev goes up a bit (add more fuel) this to make the engine reach operating temperature very quickly so yes the temperature sensor send signal to ECU to calculate how much to fuel to add but i wouldnt say its an open and close loop because its constantly monitored and changing based on other monitoring sensors

2 the 90-100 degrees doesnt activate your (open loop) the 90 degrees is the best operating temperature for a car which gives you the best performance and efficiency from both fuel per mpgs to also best effective oil temperature though new oil nowadays are multiple grades which at low temperature and high temperature it still give you the same protection

Running your car at below 80 degrees (removing thermostat) thats where you increase carbon deposit as the fuel is being burnt below the most effective operating temperature which is 90 degrees, so along the ECU is getting engine temperature reading thats are below 80 degrees the ECU will increase the air fuel ration because it should get back a 90 degrees signal from the temperature sensor therefore you damage you catalystic converter very quickly

So if the engine operating temperature reaches 90 degrees, the ECU will trim the ration becoz the operating temperature has been reached, all people who driving their cars with no thermostat are actuall running rich and the ECU is adding more fuel to help in increasing the temperature to its operating temperature of which it will never happen becoz the coolant is not being allowed to reach 90 degrees becoz its being constantly being cooled

which means open loop and close loop do exist
thanks alot

To add my more this discussion .
It actually the O2 sensor especially the sensor 1 that trigger close loop cos if Oxygen is absent, ecu will not activate close loop regardless of the temperature .

timenamoney:
which means open loop and close loop do exist
thanks alot

its not straight as open and close loop as you think, there are many variables, that can trigger to ECU to trim or add fuel, eg RPMS, throttle position, etc

1. 100 degrees celsius is not what all manufacturers use. Some use higher, some use lower.
2. The thermostat reading is not the only variable used to achieve closed loop. It is a very key variable though.
3. Let me sit back and read comments.
4. The write-up and wording can be better. I had to read multiple times to make sense of some sections.

am sorry for my confused questions that has been modified

I was curious to know if the O2 sensor is what control air/fuel ratio and when it starts controlling

, and if coolant temperature sensor must reach operating Temp before ECU allow the operation

timenamoney:
am sorry for my confused questions that has been modified

I was curious to know if the O2 sensor is what control air/fuel ratio and when it starts controlling

, and if coolant temperature sensor must reach operating Temp before ECU allow the operation

At the last part, yes CTS must register the value determined by the car manufacturer as minimum threshold to go into closed loop. The ecu then monitors other variables such as throttle position, rpm, air flow meter or map sensor, engine load, knock count etc depending on manufacturers configuration. When all parameters are within specification, the fuel system then goes into closed loop operation.
The air fuel ratio sensor feedback is now used by the ecu to control the injectors or determine amount of fuel injected into the cylinders.
The 02 sensors measure the exhaust gas leaving the catalytic converter. As their name implies, they measure the oxygen concentration in the exhaust gases exiting the catalytic converter. They may or may not be used for closed loop operation. This is dependent on manufacturer programming of the ecu. If I have erred, una fit correct am.