How to improve mileage of Honda City (current: 18 kmpl; goal: 23 kmpl)?

Sorry Krishna was away. was busy with the Ferrari F60 launch thing. And I now covering Xylo and Linea launch as well. After that I have to cover Toyota F109 launch as well. So a bit too tied up.

Talking about CAT choking, I believe in 3-4 years, get your CAT replaced if at all its choked. As you have a Honda City 2004, its OBD II, so your car will have two oxygen sensors. So the air/fuel ratio will change more often if at all the CAT is choked.

Max torque of your Honda City is 125 Nm which comes at 2700 rpm.

I have an article on Oxygen sensor as well. I'm quiet sure its full of mistakes as I haven't even read it once after reading. Will post that in an hour or so.

Cheers

Out of curiosity - Please elaborate on the above.

I was busy finding out technical stuff on the Ferrari F60. For the Xylo launch, I couldn't make it. For the Linea launch, I'm going tomorrow to the launch party and I'm waiting eagerly for the launch of Toyota F109. 

Oxygen Sensor

Introduction:

The oxygen/lambda sensor is used by the ECM to ensure that proper air/fuel mixture is used by the engine. Based on the feedback given by the oxygen sensor, the ECM calculates the amount of fuel to be injected into the main input air stream. The oxygen sensor is located in the exhaust system of the vehicle.

Initially, when the electronic systems had come into picture, cars used OBD-I system (On-board diagnostics), where only one oxygen sensor was used in the vehicle. But since OBD-II has come into existence, its principle implies to use two oxygen sensors. In cars with OBD-I, oxygen sensor is located before the catalytic converter. Whereas in OBD- II systems, one oxygen sensor is placed before the catalytic converter and the second one after it. The use of two sensors helps to reduce the air pollution to a greater extent.

Basic Function:

          Now primarily, what’s the function of an oxygen sensor? An oxygen sensor senses the amount of oxygen in the exhaust. This actually helps the ECM to sense the amount of unburnt air. Whenever air is burnt, only oxygen is the gas that is actually burnt. So sensing the amount of oxygen would give the entire scenario of how much amount of unburnt air is present, and it can be reduced or increased accordingly, to bring down the pollution level. So in short, oxygen sensor’s primary purpose is to assure almost perfect combustion of fuel so that the pollutants coming out from the vehicle are the least. And the atmosphere isn’t affected that much.

Components:

            What is the oxygen sensor made up of? Initially, Titania oxygen sensor were used, specifically in the early 90’s. But these days, zirconia (zirconium dioxide) oxygen sensors are used. It consists of zirconia, platinum electrodes and a heater. The zirconia element is attached to the platinum wires on both its sides. One platinum wire is in the exhaust pipe and the second one is exposed to the atmosphere. And a voltage of between 0-5V is passed from the ECM to the zirconia. With the difference in the amount of oxygen in the exhaust and the atmosphere, a voltage difference is generated in the zirconia. This voltage difference is sensed by the ECM and the air-fuel changes are done as per the requirement. Contamination or corrosion of platinum wires or zirconium dioxide would reduce its working efficiency.

 Operation:

            When there is lesser oxygen content in the exhaust as compared to the atmosphere, zirconia generates a higher voltage signal. And, whereas if the amount of oxygen is greater in the exhaust as compared to the atmosphere, a lower voltage signal is sent. From the oxygen content, the ECM determines whether the air/fuel ratio is rich or lean and adjusts it accordingly. A rich air/fuel mixture consumes most of the oxygen and there is hardly any oxygen left in the exhaust system and hence it sends a voltage in the range of 0.6-1.0 volts. Whereas when the mixture is lean, greater amount of oxygen is present when compared to a rich mixture and at that time a voltage signal of 0.1-0.4 volts is generated.  The chemically correct or at the stoichio


I tried this and I had understeer, I tried that and I had oversteer, at the end of the corner I just ran out of talent!

What’s the use of the heater?

An oxygen sensor functions properly only once it has reached its minimum operating temperature which is around about 400??C. Below that temperature it acts as a resistor. Hence to quickly warm up the sensor and to keep it upto the temperature at idle and light load conditions, an inbuilt heater is present in the sensor. This heater is controlled by the ECM.

PS: I haven't even read this even once since the time I have read it. Do bear with the small mistakes if any.

Cheers

O2 SENSOR:

So would you recommend playing with the O2 sensor voltage heater or modifying output (fractionally reducing the O2 sensor output voltage) rather than remapping the ECU? Would that be the easier way for improving FE ? (however, no way to access either of the O2 Sensors, maybe a tear in the muffler is required?)

ENGINE REMAP:

From the info available on the net, I see that the OBD-II remap is difficult if appropriate software is not available, as it is entirely SW oriented. Is there any shop doing remapping?

You want your car to deliver 23kmpl everytime?

Playing with the ECU and the Oxygen Sensor is not a problem. But using leaner mixture, can cause problems to your car as the temperature of the engine will rise quickly and result in higher amounts of NOx. As a large amount of air will be unburnt and will be hot, it can reduce the engine life as well. and the required efficiency isn't assured as well.

I don't want damage to the car, and still deliver me max FE , to the best extent possible. spending some money is ok but ending up with a broken engine on highway is not ok. The FE gains I want are permanent, I am not here to prove a point and slink back to my 12-15 kmpl days.

BTW 23, the figure, is my new year resolution, and there is some sanctity to it. So if you mean, remain satisfied with 21.5 (just a random higher figure than my current achievement), my answer would be NO,  tell me how I get to 23.

Then go for weight reduction. Replace your hood with a carbon fibre hood. Change the roof also by carbon fibre roof. You should reach your desired mileage, with a hole in your pocket.

Krishna, tell me what all changes have you done so far?