guys,
Everytime when i start my car, when the engine starts the ideal tuning is more in the first case. but after 2-3 seconds it comes down to normal.
This thing also happens in some bikes, but not in mine.
I want to know, why this happens? Suppose if it doesn't happen in our bike, then what it says, it is something wrong with tuning or what? What technical thing is here?

Why are you comparing a Fi car with a carbed bike?

In FI's the idle will be a abit high on a cold startup, and will come down within a few secs time. Its just the ECU warming up the engine with a rich afr. The same happens in FI bikes, but in our carbed bikes, we need to manually pull the choke to get the same effect. Hope I've been able to clarify your doubt.

Oh yeah thanks!!

All Fi Engines with O2 sensor will start at high idle RPM to warm up the O2 sensor...The O2 sensor comes in two versions,
1. Cold non heated type.
2. Heated type with built in heater.
The cold O2 sensor depends on the exhaust gas temperature to attain operating temperature, while the heated type has a built in heater to bring it up to operating temperature...so to enable the engine to start sensing the O2 out put early, the engine is programmed to be in high RPM till the O2 sensor starts sending it's value(Volts).

here is a cross section of a heated type O2 sensor..

OXYGEN SENSORS

I don't have much knowlegde or experience with petrol cars so please answer these question-
So suppose if the O2 sensor conks off,is there any pre-set amount of time for which the engine will idle at slightly high RPM before throwing a CEL and operating in limp-in mode ?
What will be the symptoms if just the heater of the O2 sensor goes bad apart from CEL ?
Does these sensors require regular cleaning or are they self cleaning ?

@all first i appologise to interrupt the thread as i am not a splendor owner but i am just a silent spectator to the spark plug discussion...

i had no idea about these resistor non resistor types...and being a complete beginner i dont know to measure as well..heck i dont know to remove the plugs and the spark plug...what should guys like me do to maintain and be up to date with spark plugs....and their condition...i know that mechanics dont check stuff such as resistance of spark plugs...i havent seen them checking at SVC or at my local mechanic(not trusted but a regular there since a last few months)

i do have a multimeter at home though(the chinese digital one)

oh!!
So this is the sensor which sends data about AFR (rich or lean) to the FI, and FI automatically adjust it right?
If they are installed on a exhaust port, then do they get clogged with carbon built-up? I don't know anything about this therefore just asking & learning.
What is their life span? How would one can know if they have gone bad or something? or may needs cleaning?

@shoeb
What does that CEL mean?

Check Engine Light
when the vehicle computer recognizes a problem in it's logic.i.e. When an expected signal value from a sensor is sent to the computer and is not within the computer's programmed specifications, 'secondary' programs are activated by the computer to strive to protect the transmission from any damage ,the improper sensor signal might cause to occur, by signaling,

In both cases of O2 sensor not working or in case of heater failure CEL will show up and a corresponding error code will be generated by the ECU..In the case of the heated type, once the Exhaust gases heat it up, it will start functioning,even if there is an error code....
In both cases the ECU will go into open loop mode.ie., go by values of Inlet Air Temperature(IAT), and Manifold Air Pressure(MAP), and function with factory set Values for injector lift and timing...again based on ECU design the , ECU may continue to drive normally with wrong AFR values, or if so programmed ,go into Limp mode.
Normally if Engine coolant or OIL over heating, or oil pressure is low, the limp mode be enabled , since these are vital fluids for the engine...Uncontrolled engine knocking,excess heating,lack of vital fluids pressure, all can lead to limp and shutdown mode...Again it depends on the ECU programme...
The O2 sensors are robust and withstand extreme temperatures for prolonged time....since it is situated near the exhaust on the manifold, it normally does not get clogged with soot..Only danger being if any of the cylinder has oil burning due to Piston ring leak the O2 sensor will get gummed up and fail.
Still once in 10 years or 50,000 kms the O2 sensor of modern engines are supposed to be replaced...Of course there are exceptions.....


There are now TWO types of Lambda(O2) sensors...The normal narrow band which has very narrow margin of detection and hence swing between 0.5 to 4.5 Volts,...and the WIDE band O2 sensor, which is linear...
As more sophistication in ECU regulation and O2 monitoring has come into vogue we see one O2 sensor in the exhaust manifold and some more in the exhaust system....

I see from your profile thatr you own a Honda Activa scooter...please go through the owner's manual which will give the guideline regarding removing Spark plug...Once removed you can check the plug with the Multimeter...

The car doesnt go into limp mode. It just runs a preset map.

True sir, a friend from TAI who'se also a senior in my college once mentioned clamping a FFF into the intake manifold of his dad's Accent, and the car started up fine CEL did'nt come up. But on connecting the ODB module it threw up an error code, which on googling he found out to be an AFR error, the same FFF was plonked in his Nano and the intake pressure went from 3~7.x psi but other than that no errors popped up and he's still running with it. In my ZEN if we disconnect the MAF Sensor or start engine without a filter nothing happens, but when we do the same to a Quadrajet the CEL comes up. So I believe you're spot on regarding different cars reacting differently based on programming.

here are some examples to explain the multi O 2 sensor positioning....



Lotus Espirit O2 arrangement..


Narrow band O2 sensor response.......................................... ................................................ Effect of temperature on O2 sensor...

Guys i have four gauges where i use the one on top left corner to check my tyre pressure which have a attatch pipe and can be remove easily.



I want to make/keep one gauge for testing compression of my engine.
Want an idea how can i make that, where i can find the jugaad? To attach this gauge to the spark plug hole?
Does a compression can be really checked with this gauge? If valves will open while cranking

Edit:
I did search and found that Schrader valve is required in the tip of the adapter so that adapter can hold air pressure.

speaking of juggad if u want to test the compression...remove the spark plug and keep a thumb pressed on the hole blocking it and crank...it the pressure blows of ur thumb(not literally blowing of like a bomb...just the pressure will be high enough that u cant keep ur thumb there) then the compression is fine....if u can manage to keep ur thumb there while cranking..u r loosing compression...not a very accurate method but u can roughly estimate