First gear clutch release operation in MPFI cars - clarification needed!

[esteem_lover]

Set your engine idling to 1000 or higher rpm & even a carb car will move without the accelerator.

The mpfi just revvs a little higher.

[1100D]

Originally Posted by rks

My Santro manual clearly advises to gradually and smoothly release the clutch while simultaneously applying the throttle.

What I think is true about MPFI cars is that it is advisable to release the clutch fully in a given gear (say, first) before either depressing it again or shifting to the next gear. I.e., I do not think it is advisable to release the clutch 50% and then depress it again and change gears or brake. I find that a mild clutch shudder develops after driving in heavy traffic where I often do not get the chance to release the clutch fully in 1st gear; I release a little and then have to brake due the traffic in front. Later when I drive in clear roads with full release of clutch, the shudder disappears after a while.

I can somehow relate to this. The last Km or two of my daily commute from office to back home is a very very painful crawl. First gear is where it stays. But it does not necessitate the need to stop completely. Hence there is this never ending clutch work, causing judder. But most of it is due to my tired left foot, rather than anything from the clutch I guess.

[rr_zen]

Originally Posted by rohan_fonseca

You can touch 4th also if one is patient enough.

You are right ! I have tried that on my brother's MPFI zen a few years back and it worked perfectly fine without any hassles whatsoever.

[Zappo]

Originally Posted by 1100D

However, there is no need for wasting fuel and time on a modern engine by idling it in the morning. The ECU does set a higher idling rpm till the engine warms up to get things lubricated.

one misconception that I always feel like clearing up on is the reason for idling in the morning. Its not just the warming up the engine bit. Its true that in modern cars ECU takes care of the temperature part of it.

However there is another good reason for it. And that is the lubrication of the internals. When the car is standing stationary, most commonly overnight, the oil that forms a protective lubricating film over the interior surface in a running engine slowly drips and collects in the sump below. So when you start the engine after a long gap it takes a vital few seconds to again start running through the interior and form the lubricating layer. This is when the parts are prone to wear and tear. That is why it is best to idle the car for 20-30 seconds before you start moving. This helps prevent the wear and tear of the "dry" parts.

In fact all turbo cars are suggested to idle for 30 seconds at least before moving on (and even before the engine is killed) to prolong the life of the the turbo.

[skandyhere]

Originally Posted by esteem_lover

Set your engine idling to 1000 or higher rpm & even a carb car will move without the accelerator.

The mpfi just revvs a little higher.

exactly. keeping the pedal depressed a little in a carb is exactly equivalent to raising the idling rpm. release the clutch without any further dip in the pedal, and it should roll on with only a tad more hesitation than an MPFI.

[rohan_fonseca]

Originally Posted by esteem_lover

Set your engine idling to 1000 or higher rpm & even a carb car will move without the accelerator.

The mpfi just revs a little higher.
Yup it just refers to the idle rpm. I guess the idle rpm is higher by default in the mpfi but shouldn't be much lower in the carbs. It just depends on how much one leaves the clutch ...specially since the zen is such a light car.

[1100D]

Originally Posted by Zappo

However there is another good reason for it. And that is the lubrication of the internals. When the car is standing stationary, most commonly overnight, the oil that forms a protective lubricating film over the interior surface in a running engine slowly drips and collects in the sump below. So when you start the engine after a long gap it takes a vital few seconds to again start running through the interior and form the lubricating layer. This is when the parts are prone to wear and tear. That is why it is best to idle the car for 20-30 seconds before you start moving. This helps prevent the wear and tear of the "dry" parts.

In fact all turbo cars are suggested to idle for 30 seconds at least before moving on (and even before the engine is killed) to prolong the life of the the turbo.

Would admit that the warming of the engine is a common misconception people nowadays have.

However the term came into usage based on engine reaching optimum operating temperature, which doesn't only mean that the oil is circulated across, but has reached the optimum viscosity (which is temp dependent). I remember being told this by a old driver when I was very small. Confirmed it from more reliable sources. However, when I ask the current bunch of drivers the same question, I never get a good answer.

The moment you crank up the car, the oil pump gets to work, but the oil does not stay in the correct viscosity range to protect the engine. But likewise as you mentioned 20 secs of idling is always recommended (generally start the engine first and then fiddle with the seatbelts and CD's), but not going on idling till the engine reaches the optimum temperature (which most uninformed people do).

One more thing, more you idle on a cold engine, you let more pollutants inside your house.

[ron_9191]

I dont know whether i am correct here but i would say it is better to idle atleast for a minute or 2. I own a Baleno and what i have noticed on that is when you start it up in the morning the RPM stays at 1.5 or sometimes 1.8 for almost 10 or 15 seconds and then takes around a miunte or 2 to come down to 1k. So my thinking is that you need to idle atleast for that to happen.

[risga]

Another feature of the MPFI cars, which I discovered recently.

If you gradually release the clutch, without depressing the accellerator, car moves forward. This is well known.

Now if the road has a slope, even then car will not stall, but RPM will be maintained by ECU and car continues to move forward up the slope.

[vnabhi]

Originally Posted by Zappo

For me, no clutch has always meant no clutch except when I am shifting gears. In heavy bumper to bumper traffic (which I face right from Panjagutta (Hyd) while going back home in the evening) I just make myself forget for a while that I have a gas pedal. I just shift on to 1st gear the moment the car in front starts to roll. Release the clutch slowly. My car starts rolling. Often the crawl stops immediately and its time to shift to neutral and wait. Once the crawl begins its the same routine again. If the crawl continues for a while the car keeps rolling along nicely. No clutch, no accelerator. If the crawl turns to roll I just shift over to 2nd. Nice, now I am happily rolling.

Who needs a clutch or a gas pedal in traffic.

Ditto style of driving, 100%, at the same godforsaken place. Punjagutta was outside my radar for the past 3 months, and I used to take the Taj Krishna-KCP junction route.
But now it appears that Punjagutta is better, as KCP Jn seems to be the new 'jam' point.

[BlackPearl]

Originally Posted by ron_9191

I dont know whether i am correct here but i would say it is better to idle atleast for a minute or 2. I own a Baleno and what i have noticed on that is when you start it up in the morning the RPM stays at 1.5 or sometimes 1.8 for almost 10 or 15 seconds and then takes around a miunte or 2 to come down to 1k. So my thinking is that you need to idle atleast for that to happen.

I think 2 mins is not needed. 20 secs should be ok. The rpm in Baleno shoots to 1.2 K but never to 1.5 or 1.8 K

[sreenivass]

Originally Posted by Zappo

one misconception that I always feel like clearing up on is the reason for idling in the morning. Its not just the warming up the engine bit. Its true that in modern cars ECU takes care of the temperature part of it.

However there is another good reason for it. And that is the lubrication of the internals. When the car is standing stationary, most commonly overnight, the oil that forms a protective lubricating film over the interior surface in a running engine slowly drips and collects in the sump below. So when you start the engine after a long gap it takes a vital few seconds to again start running through the interior and form the lubricating layer. This is when the parts are prone to wear and tear. That is why it is best to idle the car for 20-30 seconds before you start moving. This helps prevent the wear and tear of the "dry" parts.

In fact all turbo cars are suggested to idle for 30 seconds at least before moving on (and even before the engine is killed) to prolong the life of the the turbo.

Originally Posted by 1100D

Would admit that the warming of the engine is a common misconception people nowadays have.

However the term came into usage based on engine reaching optimum operating temperature, which doesn't only mean that the oil is circulated across, but has reached the optimum viscosity (which is temp dependent). I remember being told this by a old driver when I was very small. Confirmed it from more reliable sources. However, when I ask the current bunch of drivers the same question, I never get a good answer.

The moment you crank up the car, the oil pump gets to work, but the oil does not stay in the correct viscosity range to protect the engine. But likewise as you mentioned 20 secs of idling is always recommended (generally start the engine first and then fiddle with the seatbelts and CD's), but not going on idling till the engine reaches the optimum temperature (which most uninformed people do).

One more thing, more you idle on a cold engine, you let more pollutants inside your house.

These observations seem to contradict with what manufacturers recommend. If the ECU is feeding richer fuel/ mix, is it not taking care of extra lubrication needs upon cold start. On some cars you are expected to crank it after fule pump starts, which means dry parts get some degree of lubrication. Coming to moving components like transmission, bearings, tires, ... what better way than driving around ?

The recommendation: wait for just a couple of seconds max before moving away, be gentle for the first few KMs or minutes seems like a very good balance of minimal damage on internal components, minimal pollution and less hit on FE.

[rranjith_kum]

Originally Posted by moralfibre

I use this to my advantage in cold starts. Here is what I do:

1) Crank the engine when cold. RPM is about 1200.
2) Release the clutch without using the accelerator and car begins to roll.
3) Engage second gear and the car keeps rolling at the same rpm.
4) Engage third with same results and after about 2-3 mins of driving this way I step on gas. Helps quite a lot in getting better FE.

i didn't believe my santro could go on up to 3rd gear without gas however after reading your post i tried it out this morning (of course i should confess that i was surprised) it did manage till 3rd gear without accelerator pedal but it quite almost stalled in the 3rd gear initially with the gear knob literally oscillating, i should say, then things eased off ... i should also mention that during my first run i even pressed the accelerator pedal very very little after the first gear and immediately took off the leg and only after the engine coming down to the idle rpm i shifted to 2nd ... i did this because i wasn't confident the my santro would come to 2nd gear itself without the gas ... but it came up to the 3rd gear without gas

however i remember very well in the manual the suggested ideal shifting speed for 3rd gear is above 20kmph... i would agree it works but its not advisable, that is what i feel...
trying out these i was late to the morning classes in college

[doomsday]

Originally Posted by Zappo

one misconception that I always feel like clearing up on is the reason for idling in the morning. Its not just the warming up the engine bit. Its true that in modern cars ECU takes care of the temperature part of it.

However there is another good reason for it. And that is the lubrication of the internals. When the car is standing stationary, most commonly overnight, the oil that forms a protective lubricating film over the interior surface in a running engine slowly drips and collects in the sump below. So when you start the engine after a long gap it takes a vital few seconds to again start running through the interior and form the lubricating layer. This is when the parts are prone to wear and tear. That is why it is best to idle the car for 20-30 seconds before you start moving. This helps prevent the wear and tear of the "dry" parts.

Very true- after the car is parked overnight/few hours - the oil is collected in the oil sump/pan. So once the engine is cranked up- the oil pump starts circulating the oil throughout the internals of the engine. This takes a few seconds and hence it is recommended to let the car at idle (no need to use the gas pedal) for a few seconds before pulling away and taking it easy for the first few kilometers.

Originally Posted by Zappo

In fact all turbo cars are suggested to idle for 30 seconds at least before moving on (and even before the engine is killed) to prolong the life of the the turbo.

This is the job of the Turbo Timer. Usually the cars which are turbocharged from the factory have a factory fitted TT which keeps the engine running for a stipulated time and then turns it off even after you switch off the ignition and lock the car and walk off.

[chetanhanda]

Originally Posted by sreenivass

These observations seem to contradict with what manufacturers recommend. If the ECU is feeding richer fuel/ mix, is it not taking care of extra lubrication needs upon cold start. On some cars you are expected to crank it after fule pump starts, which means dry parts get some degree of lubrication. ?

fuel pump will not lubricate the engine at all. the engine oil needs to circulate, even if the fuel pump was on before the engine is cranked it wont make a difference at all, the electric fuel pump will simply make the fuel flow thru the fuel lines and back to the tank...

We want to "wet" the "dry" parts with oil,so we need to crank the engine, the fuel lines flow in a different circuit

If u had a dry sump system then it would make sense to switch on the "oil pump" for lubrication before cranking up the engine... with a wet sump u cant lubricate the engine unless u crank it up ...