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Old 13th March 2006, 02:17   #16
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Don't know about all the other MPFI cars out there, but my E2 Esteem gets grumpy and throws tantrums if I dont let her warm up to at least the cold mark before starting off...

On a very cold morning, she idles at 1500 rpm and takes as much as 3 minutes to settle down to her "normal" 800 rpm... If I use the accelerator or put load on the engine (drive off using only the clutch), the ECU gets "confused" and then refuses to bring the idle speed down from 1500 RPM till I "reboot" it ! (Turn off the engine, wait a few seconds then restart).

I have heard of a similar behavior from many other Maruti owners including a new Swift owner... a case of Maruti cutting corners with something perhaps?

I have a couple of friends with Santro Xings and although these cars rev high to warm the engine, driving them in this state does not confuse their ECUs. The car settles down to its normal idling speed once the engine is warm regardless of whether it was driven.

- T u r b o C -
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Old 13th March 2006, 06:10   #17
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Quote:
Originally Posted by adya33
in practical life that temprature variation is so small that change in physical measurment of metallic parts doesn't even come into play

In actual practice, the temperature variations are huge, can be upto 300 deg Celsius for pisont crown to in tens of deg Celsius for bottom of skirt. The thermal stresses setup are huge. The variations in physical dimensions depends to the type of materials used (higher for aluminium and lower for steel), but not negligible considering the stresses (to confirm this you can check the butt <circumferential> clearances of the piston rings. the top ones have the highest and the bottom one have the lowest)

The engine should be warmed up to come to working temperature, whether it is MPFI or not because to avoid different rate of expansion in the beginning and setting up undue additional stresses and thus increasing wear and tear. But then fuel economy goes down. So a balance is to maintained, that is how much should warm up and how much you should save on fuel.

Thumb rule is that warming up depends on climate, that is colder the weather, longer you warm up. Also if you start pulling out of your garage at a very slow speed, it is like warming up. In winter you can let the engine idle for a minute or so depending on outside temperature. If the engine lube flow feels sluggish, drive at low speed and accelerate.

RK
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Old 14th March 2006, 08:02   #18
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Quote:
Originally Posted by Rehaan
Nitrous - Please disagree in a polite manner!

And even though i disagree with his point, he did not say anything about the ECU letting you revv beyond a certain limit when cold. (Although cars like the E46 M3 have a revvlimit that changes as the car warms up)

I think what he means is that on carb cars, if the car is not warmed up enough, the engine will stall occasionally (in cold conditions) if you just let it idle (if the idle speed screw is set at a low enough setting), but in MPFI cars that doesnt happen since the ECU keeps it idling higher till it warms up.

Devarshi, read the thread and see why we say idling is important before you dismiss it by saying its not neccessary on MPFI cars.

cya
R
yeah that's what i meant.
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Old 14th March 2006, 12:42   #19
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When I start the car for the first time everyday, the idling begins at 1200 rpm and then slowly comes down to 850rpm. Most of the time I dont wait for it to come to 800rpm. I start moving at 1000 rpm but make sure that I dont rev it more than 2500rpm for atleast about 2/3 kms. This I am sure is not gonna do any harm to the engine.
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Old 14th March 2006, 13:01   #20
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Another variable here.

What if we're using synthetic/super-syn engine oil??
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Old 18th March 2006, 16:27   #21
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When idling the vehicle for morning start, do I need to look at the temp gauge ?

And by looking at the temp gauge can I able to assess whether the idling is enough ?
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Old 18th March 2006, 17:16   #22
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Mithun , you can look at the RPM gauge instead of the temp gauge. The idling should settle down to normal in about a minute while the temperature gauge takes time to get moving.

From what I have observed, the temperature gauge starts moving after you have driven for some time. And yes do take care that you dont rev your engines till the temperature gauge has reached atleast the 3/4th mark. Hope this helps.

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Old 18th March 2006, 19:04   #23
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Quote:
Originally Posted by mithun
When idling the vehicle for morning start, do I need to look at the temp gauge ?

And by looking at the temp gauge can I able to assess whether the idling is enough ?
i am considering that your car doesnot have a tachometer.
start the engine and notice minutely that if, even a slight tapping on the accelarator pedal throws revs to some higher range, it is better to wait for sometime.
and if after the slight tapping on acc. pedal, revs don't goes too high, then you can drive it modestly for some distance say for 1km. the you can drive it the way you want!

it is reqd only after a stop-over of car of about 4-5 hours atleast. anything lesser doesnot needs so much of waiting.

now, if your car has the tachometer, just wait for it to come around 1000RPMs or so.

the basic idea behind such a wait while idling is to let lubrication to spread all over the engine. it can be considered just as a 'practice' and not necessary to follow it. but if you really cares about your car, then i guess 30-60 seconds are not much!
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Old 18th March 2006, 19:07   #24
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Quote:
Originally Posted by nitrous
Another variable here.

What if we're using synthetic/super-syn engine oil??
you can use any engine oil, but after a stop-over of, say overnight, will reduce some amount of lubrication from the parts that faces the most friction. it is 'advisable' to follow the warming up practice, not compulsory though.
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Old 28th March 2006, 19:10   #25
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Default idling problem after cold start

hi I have a 1.2L palio petrol in India. done 21000kms. 1 and half year old.

i have the same problem the revs shoot about 400 to 500 rpms more than my accelerator lnput. it happens only for 1 to 2 kms after a cold start. on pressing the clutch, the revs shoot up to 1500 revs( normal 850-950 revs).
It automatically stops after the engine temperature increases.

please help.. as the car accelerates without me pressing the throttle....
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Old 28th March 2006, 19:56   #26
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Don't worry. this is normal. try searching the same topic on the forum. Explanation for this phenomenon has already been explained in detail.
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Old 28th March 2006, 21:36   #27
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Yes man ... Chill... Not an issue... You got nothing to worry about!
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Old 28th March 2006, 21:48   #28
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There are so many topics ..on team-bhp.. on this subject!.... search

Also you noted this after 21,000 kms?
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Old 29th March 2006, 02:27   #29
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get all the sensors including the oxygen sensor and throttle position sensor checked,it might resolve the problem
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Old 29th March 2006, 03:32   #30
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Quote:
Originally Posted by .anshuman
get all the sensors including the oxygen sensor and throttle position sensor checked,it might resolve the problem
Why ? for what reason ? there is nothing wrong with what he has described.I feel what he has described is not of concern at all.
It is normal for the engine to rev high till it comes to operating temperature.
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