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Old 3rd May 2013, 19:19   #31
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Default Re: Car moves forward without pressing the accelerator ...normal?

Never tried other gears, but my Alto K10 moves at around 10km/h in first and 20 in second, without accelerator input as long as the clutch is released slowly.
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Old 4th May 2013, 00:33   #32
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Default Re: Car moves forward without pressing the accelerator ...normal?

I was told by my driving instructor many years back that this is a normal feature of all mpfi engines. I dont know the mechanics of why though.
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Old 4th May 2013, 13:11   #33
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Default Re: Car moves forward without pressing the accelerator ...normal?

Once the Mpfi engine senses load being applied on the engine, it increases idle speed to a level at which the engine wont stall. When I park my car inside the apartment, during which I control the car using half clutch and brake, the moment I press the clutch, the idle speed increases and then settles. This shows that the ECU was preventing the engine from stalling during half clutch application. Similarly, both my cars launch from stop without using the accelerator when the clutch is released slowly. If the car is not fully loaded or AC is off, the car can manage to even launch on a minor incline too.

During a sedate drive, I can reach 50-60kmh in my Sx4 without touching the accelarator. Just shift to gear and leave the car in each gear for sometime before upshifting.
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Old 4th May 2013, 18:28   #34
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Default Re: Car moves forward without pressing the accelerator ...normal?

Quote:
Originally Posted by Ragul View Post
I was told by my driving instructor many years back that this is a normal feature of all mpfi engines. ...
Quote:
Originally Posted by audioholic View Post
Once the Mpfi engine senses load being applied on the engine, it increases idle speed to a level at which the engine wont stall. ...
Correct, but ... It doesn't sense load or whether the vehicle is in gear or whether the clutch is depressed or not - just the dip in idle RPM.

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... During a sedate drive, I can reach 50-60kmh in my Sx4 without touching the accelarator. ...
Reminds me of an old joke: A Nawab would boast about the length of the tigers he had killed. His adviser politely told him to reduce the length if the he coughed. So one day, the Nawab was upto his usual boast, but went "60'" *cough* "No - 50'" *cough* *cough* "Umm ... maybe 40'". Finally he got frustrated and admonished the poor adviser - "You can kill yourself coughing, but I am not going to go below 30'"

*Cough* *cough* *cough* *cough*

Please look at the gear ratios, the idle RPM and the power needed. You can do it on a down slope - but then you wouldn't need to do it, right, it would do it even with engine off?

Last edited by DerAlte : 4th May 2013 at 18:34.
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Old 4th May 2013, 19:11   #35
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Default Re: Car moves forward without pressing the accelerator ...normal?

I learnt driving on a carbed M800. It (car moving without accelerator) never happened on that particular car. However when i tried mt hands on MPFI WagonR, it used to happen. Infact due to this very problem, i took a very long time to get adjusted to my WagonR form old M800
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Old 4th May 2013, 19:48   #36
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Default Re: Car moves forward without pressing the accelerator ...normal?

With all due respects, I do not think maintaining Idling rpm is the goal of the ECU. If that were to be true, a chevy spark cant do 40kmh in fifth gear, neither would a punto do 50kmh as stated by the previous replies. When the car is able to do 80-90 with slightest pressure on the gas, there aint a reason to cough about what I said. And that is not a great thing to boast about too. Just mentioned what I observed. Sorry if that sounded like a joke to you. At least I am happy you might have had a good laugh.

Last edited by audioholic : 4th May 2013 at 19:57.
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Old 4th May 2013, 21:42   #37
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Default Re: Car moves forward without pressing the accelerator ...normal?

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... I do not think maintaining Idling rpm is the goal of the ECU. ...
ONE of the PRIMARY goals. Any engine control ECU - petrol or diesel. One doesn't have to have an opinion on that - that is a fact.

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... If that were to be true, a chevy spark cant do 40kmh in fifth gear, ...
Not in idle, unless you are going down slope as I mentioned earlier! It will stall if you are below 20 and press the gas pedal without changing gear to 2nd. Not enough torque in 5th gear, not enough power generated by 'idling fuel quantity'. Please try it.

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... When the car is able to do 80-90 with slightest pressure on the gas, ... At least I am happy you might have had a good laugh.
Thank you for your continued support.
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Old 13th December 2014, 11:51   #38
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Default Re: Car moves forward without pressing the accelerator ...normal?

Hi guys,

My petrol car's clutch-release-starting (if we can call this thing that), has reduced recently.

Now if I start releasing the clutch; halfway through, the rpm almost drops. And unless I keep the clutch depressed at that position, it dies. If I keep the clutch at that position for bout a second, the car starts rolling.

No other issue with the car.
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Old 13th December 2014, 15:47   #39
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Default Re: Car moves forward without pressing the accelerator ...normal?

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Now if I start releasing the clutch; halfway through, the rpm almost drops. And unless I keep the clutch depressed at that position, it dies.
It is normal for the RPM to fall below idle as there is load being encountered.

Quote:
If I keep the clutch at that position for bout a second, the car starts rolling.
The momentum has been achieved when you hold the clutch at that half way point but IIRC it'll kill the clutch if done repeatedly. IMO you need to get the clutch checked once.

Anurag.
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Old 20th December 2014, 15:38   #40
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I have an i20 crdi and when I put it in first gear, it lunges ahead even with minimal release of the clutch. The Fortuner does the same but with the clutch at least halfway through. Engine size and vehicle size difference, I guess.
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Old 20th December 2014, 16:15   #41
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Default Re: Car moves forward without pressing the accelerator ...normal?

It is perfectly normal. I have come across several instances where my friends who went to motor training schools were taught like this itself (Engage 1st and leave the clutch slowly without accelerator input to set the vehicle in motion).

Have myself experienced this on every Diesel/Petrol car I've driven. Infact, it is possible even in motorcycles. 1st gear speed in bikes without accelerator input is around 8-12 kmph(in 150cc engines).

-Bhargav
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Old 20th December 2014, 17:29   #42
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Default Re: Car moves forward without pressing the accelerator ...normal?

Not only is this absolutely normal, it is great when strolling when in slow bumper to bumper traffic!
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Old 20th December 2014, 18:54   #43
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Default Re: Car moves forward without pressing the accelerator ...normal?

The same is true for the Alto K10 AMT, the car moves forward on releasing the brake without any accelerator input.

It takes a little time getting used to it, esp when taking the car out from a parked area with another car parked very close in the front! Faced this problem yesterday.

Last edited by wishnipon : 20th December 2014 at 18:55.
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Old 21st December 2014, 02:41   #44
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A common behaviour of diesel engines to lurch forward the moment clutch is released. It is absolutely normal.

Quote:
Originally Posted by kkdelhi View Post
I have an i20 crdi and when I put it in first gear, it lunges ahead even with minimal release of the clutch. The Fortuner does the same but with the clutch at least halfway through. Engine size and vehicle size difference, I guess.
Either clutch is pressed or fully released, relating it half is dangerous and may fry your clutch. Bumper-2-bumper traffic demands using if half clutch but i feel it damages the engine.

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Originally Posted by nishantbhatia84 View Post
Not only is this absolutely normal, it is great when strolling when in slow bumper to bumper traffic!
Not good for engine and transmission if the half clutch used be used.

Anurag.

Last edited by a4anurag : 21st December 2014 at 02:44.
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Old 28th December 2014, 00:37   #45
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This is a feature of modern MPFI engines.
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