Ads 468x60px

Kamis, 15 Juli 2010

Lambda Sensor - Definition and functioning

The statement:

Lambda sensor (also called as oxygen sensor) helps in fuel+air mixture and not the 'oxygen content in the exhaust gasses' ! :) - Is incorrect.
 
The correct statement should be: 
Lambda sensor (also called as oxygen sensor) helps in fuel+air mixture by measuring the 'oxygen content in the exhaust gasses' ! :)
 
Here is the an explanation for the above confusion - Automotive oxygen sensors, colloquially known as O2 sensors, make modern electronic fuel injection and emission control possible. They help determine, in real time, if the air fuel ratio of a combustion engine is rich or lean. Since oxygen sensors are located in the exhaust stream, they do not directly measure the air or the fuel entering the engine. But when information from oxygen sensors is coupled with information from other sources, it can be used to indirectly determine the air-to-fuel ratio.



 
Thus, the definition of a Lambda sensor - Sensor fitted to exhaust systems to measure the oxygen content of exhaust gases. Is correct.



Below is the portion of one of the very earlier posts by our won Dr.Sunil Pullockaran addressing the FE issues on Palios. Please read through and im sure this will be the best read allowing you to understand what dictates FE and how you ensure you get reasonable figures out of your car. by the way, Lambda sensor (also called as oxygen sensor) helps in fuel+air mixture and not the 'oxygen content in the exhaust gasses' ! :)


Sincere apologies on a slight wiring error. In my previous post I had mentioned the heater of the Oxygen sensor to be colourd white but actually the correct wiring is Lead 1 and 2 coloured black(+) and grey(-) are the sensor leads and the 3 and 4th leads coloured white are the heater leads for the oxygen sensor. One more precaution is never to use the resistance check on the sensor and always use the DC voltage reading check. Last night I wrote the post late at night nad hence the error so please forgive me. I went and checked the same today morning and my sensor occasionally shows a reading of 1.2 volt which is a little above normal and also reset the ECU. Bye and wear your seatbelts.


In the daily digest I read a few members claiming that they managed a fuel effeciency of just 6 to 9 km perlitre which is near impossible if you go through a few tips I am about to give which has been given before in past posts but for the benefit of new members I will go through the same once again. Remember I am an orthodontist by profession so you can just ignore suggestions coming from someone in the medical field but these tips work wonders on my GTX which gives 9.8km/litre in the city and about 12.4 to 13 on the highway and I never switch off the AC.



1) The next time you go to the service centre make sure your suspension components are in top condition and by that I mean all rubber bushings of the front and especially the rear suspension. Replace any bush even slightly out of conformity which can be assessed by any trained mechanic working at the authorized service centre.



2)Using the tape and or rope method which I have described in detail in previous posts make sure the toe-in of your front tyres are +0.5 mm and yes I did mention in millimeters and not degrees. I am absolutely convinced the computerised wheel alignment offered in our service centres are just not perfect enough in the hands of our less than well trained wheel alignment mechanics.



3)Get a digital multimeter of atleast Rs 300 or more and do not ever use the analogue meters as they will ruin the component I am asking you to check which costs about Rs2000. Bring your car to optimum running temperature and switch off the engine and disconnect the battery cables I repeat again disconnect the battery cables.This battery disconnection is to prevent the possible frying of your ECU similar to the frying of your motherboard and or CPU and memory modules when you attempt to remove a PCI card without switching of the computer power completely. I have fried my computer on two occations in my early days at assembling computers. Remove the four pin connector of the Oxygen sensor/Lambda sensor which resembles a spark plug sitting at the exit of the exhaust gases from the engine to the exhaust manifold. Of the four leads two will be of the same colour in my cars case two are grey which are for the quick heating of the sensor using a heater element. The other two in my GTX the important ones are coloured black and white and they are huddled together at the other corner of the four pin connector which are the pins that output 0.4 to 0.8 volt at idling. Using your multimeter leads practise a few times to touch the black and white leads of the sensor without shorting them as shorting them when they are out putting voltage will ruin their sensitivity. Remember all this with your battery disconnected and the engine off need I say. Once you get the hang of it reconnect your battery terminals which by now would have drained all learned paremeters in other words you would have reset your ECU.

Next start your car with the disconnected Oxygen sensor. Check that your car is at optimum running temperature and then using your digital multimeter not analogue meter check the voltage output from the black
and white leads. They should read 0.6 -to 0.8 volts and should keep varying at a furious rate between these extremes and if they vary by a wider margin like 0.4 to 0.9 volts all the better the important thing being this should be varying at a furious pace like two to three different readings a second and they should read atleast 0.8 volts occassionaly when your friend/wife blips the throttle. Through all this make sure your hands are steady as shorting the leads will ruin your oxygen sensor but not the ECU as the sensor you have already disconnected. Like spark plugs and oil dampers the Lamda sensor weaken over time and need replacement every 30000km or more but much sooner if there are contaminants in the fuel like silicon or radiator fluid from a failed head gasket. I am hands on type of guy so for those who are vary of ruining your sensor go to the authorized service centre and hook up the FIAT computer and check your Oxygen sensor. More often than not all guys who have poor fuel effeciency have a defective/weak Oxygen sensor.



I am very happy with the 9.8km/litre I get in my GTX in cochin with AC in the city and if you guys do not get 11 in the NV then go through these three points and one of them will be the culprit. Bye and do wear your seatbelts. Before I forget Sania has made our nation proud hats of to her and especially her parents for allowing her to train even though from a conservative Muslim family in Hyderabad. Do you guys know about the story about the NIZAM of Hyderabad wanting to accede to Pakistan during the time of partition. If not for Krishna Menon Hyderbad in Andhra would have been part of Pakistan and so would Sania Mirza.


I think that is precisely what Chandan has actually tried to convey in his post, but maybe not in so many words. But admittedly the meaning came out loud and clear. Terming it as incorrect might be a bit too harsh, dont you think? No harshness, intended towards anybody. Smile.

 
What made you think that my email was addressed to Chandan. It was not. Again, sorry for any ruffled feathers.   Feathers? I dont see any feathers in this group. Body hair and animal fur maybe. But definitely not feathers. No birds here.


If we were chickens, we would be going around in anything else but a Fiat, wouldn't we?

 I know for a fact that Arindam loves birds, i.e, the edible ones. So I  guess that is where it's coming from. Though I would rather that his preferred expression would be "Tipping the Scales" Arindam- please correct me if I am wrong :)

0 comments:

Posting Komentar