Letting engine idle for a while on a cold start.

[TheMirror]

Hello all,

My dad believes that on a cold start, you should let the car idle for a while before driving. When you initially start the car it's at about 1500rpm, and he says to let it drop till 1000rpm before driving off.

Is this just an old technique which he would've been neccessary for olden day cars, or is it actually better for the car to let it idle for a bit?

Thanks

[DJKOR]

Ive made a reply to this before, so I will repost:

Cold Start

...

Toyota recommend that you start driving immediately without letting it sit to warm up. This stems from emissions mainly I would guess, but there is probably other factors at play here like having a load on the engine etc.

My recommendations would be to start you car then when the revs drop to around 1000 RPM or lower and the temperature needle moves onto the scale, then you can start driving it. This should take around 30 seconds to a minute from a complete cold start. Once you start driving just try not to get your revs high (I usually stay below 2500-3000 RPM) and within about 5 minutes, it should be warmed up sufficiently. It's easier to do if you have some suburb to drive thought as you leave your house.

Just for reference on some of the extra noise on the normal Aurion's:

Aurion takes forever to warm up

This is also what others on this board have recommended in previous threads. Here is a thread started in 2007 as well which contains about the same idea:

V6 Engine REVS When Cold

[Silver-Aurion]

I'll do what DJKOR says, RTFM. It states in the manual to NOT to do this, especially in newer cars, what I do though on cold starts, is at least leave for 10 seconds, and 15 seconds max on cold nights and then drive off very easy and let the car warm up to full running temp then you can give it stick.

On every cold start, I'll leave for at least 10 seconds then drive, I wont turn it on and chuck it in D straight away. But leaving it any longer is just wasting fuel and your time and apparently not good for the engine in new cars.

edit: Your too fast!

Edited January 7, 2010 by unique

[TheMirror]

Ive made a reply to this before, so I will repost:

Sorry, should've done a quick search.

It states in the manual to NOT to do this....and apparently not good for the engine in new cars

I read the manual, and can't find where it says this. The only things about cold starting I could find were "Do not race a cold engine" and under the "How to save fuel section pg 215", it says

Avoid lengthy warm-up idling. - Once the engine is running smoothly, begin driving -but gently

Could you please give me a reference to where it says its BAD for new car engines? Still unsure whether I should leave the car for a while if it doesn't damage it..

Cheers.

[prometheus]

On a cold winter morning or day , I think its quite ok to let the engine idle for a minute before driving off , and then driving sensibly until the engine reaches its optimum operating temperature.

With modern cars and the thin oil that they use , warming up for more than a minute is probably not really necassary. Provided you don't push the car hard initially.

Or just go by how your particular car "feels" when you have a cold start when the car has been sitting there for 9 - 10 hours or more.

Off topic.

I remember talking to a mechanic a few years ago , he told me how his then girlfriend had bought a new Ford Probe ( a coupe ) , he drove it home from the dealers and gave it a nice "thrashing" so as to run the engine in , knowing that his girlfriend would baby the car when she drove it.

[Silver-Aurion]

Ive made a reply to this before, so I will repost:

Sorry, should've done a quick search.

It states in the manual to NOT to do this....and apparently not good for the engine in new cars

I read the manual, and can't find where it says this. The only things about cold starting I could find were "Do not race a cold engine" and under the "How to save fuel section pg 215", it says

Avoid lengthy warm-up idling. - Once the engine is running smoothly, begin driving -but gently

Could you please give me a reference to where it says its BAD for new car engines? Still unsure whether I should leave the car for a while if it doesn't damage it..

Cheers.

I had to pull out my manual and search this just for you...

Go to Page 201. "Engine should be warmed up by driving, not in idle..." continue reading that section in the manual.

I only heard its "bad" which by that I meant you are adding unnecessary wear and tear to an engine that does not require 15seconds+ warm up time. Imagine you leave your car to warm up each morning for lets say 3minutes, and over its life that add's up. Its best to leave it for few seconds, and drive very easy to warm it up, which is even recommend in the manual.

Your adding unnecessary wear and tear because in idle the oils don't move around properly while warming up in idle, so gradually warming up by driving lubricates the engine properly.

The MAX I would do in an Aurion is 1 minute in freezing Melbourne winters where it can be 5 degrees on some mornings.

My dad is old school and thinks I need to warm up my car like his old 92 carby engine

Hope this helps.

Edited January 7, 2010 by unique

[Guni]

[Silver-Aurion]

What are you laughing at...

[Freddo]

Ive made a reply to this before, so I will repost:

Sorry, should've done a quick search.

It states in the manual to NOT to do this....and apparently not good for the engine in new cars

I read the manual, and can't find where it says this. The only things about cold starting I could find were "Do not race a cold engine" and under the "How to save fuel section pg 215", it says

Avoid lengthy warm-up idling. - Once the engine is running smoothly, begin driving -but gently

Could you please give me a reference to where it says its BAD for new car engines? Still unsure whether I should leave the car for a while if it doesn't damage it..

Cheers.

I had to pull out my manual and search this just for you...

Go to Page 201. "Engine should be warmed up by driving, not in idle..." continue reading that section in the manual.

I only heard its "bad" which by that I meant you are adding unnecessary wear and tear to an engine that does not require 15seconds+ warm up time. Imagine you leave your car to warm up each morning for lets say 3minutes, and over its life that add's up. Its best to leave it for few seconds, and drive very easy to warm it up, which is even recommend in the manual.

Your adding unnecessary wear and tear because in idle the oils don't move around properly while warming up in idle, so gradually warming up by driving lubricates the engine properly.

The MAX I would do in an Aurion is 1 minute in freezing Melbourne winters where it can be 5 degrees on some mornings.

My dad is old school and thinks I need to warm up my car like his old 92 carby engine

Hope this helps.

even in my twin turbo i wouldn't let it sit idle... i'd slowly drive it off and not rev it past 3thou.

different chains of thought i guess!?

[DJKOR]

My theory is that is has to do with having load on it while it is cold. I'm no expert on the subject, but I would imagine that when the engine is cold and the clearances are greater in the engine, having a load on it will make everything run more balanced reducing wear.

I dunno, just a theory.

[David the Viking]

An engine has a lot of components that are made of disimilar metals (aluminium alloys, steel & cast iron) which all heat and expand at different rates. This is why they say not to race a cold engine.

An idling car has very bad emissions which is why they say to warm it up while driving. Its all to do with thermal efficiency which is why automatic stop/start (no more idling at lights etc.) and cylinder deactivation (Holden V8 AFM) technology will be more prevalent in the future.

I may have mentioned it before but I let the revs settle back down to the 1000rpm after starting which usually only takes a few seconds and by that time the engines oil pressure would have built and stabilised as well as the transmission fluid will have started to circulate properly. By letting the revs drop down I find it is much smoother selecting reverse and off I go. Then I take it easy until the engine temp gets close to normal.

[TheMirror]

Thanks everyone for your help. Yeah, I never leave the car on for like 3 minutes, only till the rpm goes to about 1000, which take about 45 seconds on in the morning.

Thanks.

[httttt]

I personally don't idle at all but don't launch fast or exceed the speed limit until the temperature needle is stable.

I have a habit of clicking the cars I drive to ON and listening to wait for the fuel pump to do it's thing (about 3-5 seconds) then I turn the engine over. I'm not sure if that does anything for the engine but I have always done it.

[69.NIX]

think of starting the car like waking up.

If you get push and shoved out of bed, your gonna be a grumpy old fart and might complain a bit. If you wake at a "normal rate", you feel a bit more composed and will work better through the day.

/my 2 cents

[Silver-Aurion]

think of starting the car like waking up.

If you get push and shoved out of bed, your gonna be a grumpy old fart and might complain a bit. If you wake at a "normal rate", you feel a bit more composed and will work better through the day.

/my 2 cents

Same here.

[VF-X]

Sorry for a revival of an old thread. I know it's normal to have a high engine revs when starting after putting your car to sleep for like 12 hours or more. Is it normal thou to have a medium engine revs when starting after the same period of time?

I noticed my car used to point to 2k rpm when starting, but now, apart from the sound that it makes, now it always start from around 1.5. I looked at the temp, it's still on the lowest temp.

Is this something I should be worrying about? long term?

[DJKOR]

Is this something I should be worrying about? long term?

There is nothing to worry about mate. The idle speed is all electronically controlled and over time, it can adjust so that it has a lower idle starting RPM than it once had before. This could be due to a number of reasons, but the one I would be guessing is doing this is for emissions control.