Warming up engine is useless and waste gas

[Garak]

Originally Posted By: Stewie
What do you guys think?

That was clearly written one year before Ontario's latest cold snap. If he wants to dress up like a snowmobiler and drive off in 30 seconds in -40, all the while avoiding breathing in his interior until the engine gets some heat into it, all the power to him.

Yes, fuel injection systems run much better in the cold than carbs did. Carbs did start better, but keeping the engine running sometimes could be a challenge. One cannot argue the point that one can actually get in and drive a fuel injected vehicle immediately. That's true. But, if it's much below -15 C, there is going to be a slight warmup period, especially if I've had the vehicle off for many hours.

Fortunately for me, the G37 generates a lot of heat in very short order.

Originally Posted By: Shannow
demarpaint, given that I doubt anyone regularly drives a carbed engine these days....

Well....

My F-150 was the last year of carbs for that model.

 

[901Memphis]

Yeah, I let it run all day so I can leave the air conditioner on. That way it's nice and cool when I drive home. I gotta gas up sometimes over lunch, but it's worth it.

 

[djb]

I suspect that many of us are living with the legacy of 'wisdom' that was valid once, but no longer applies.

Carburetors are horrible beasts. They were an elaborate mechanical computer that tried to create a usable fuel-air mixture over a broad range of air pressure, air temperature, air flow, fuel blends, engine load, and engine temperature.

It's no surprise that they worked badly at temperatures where the fuel barely evaporates and low air flows where the fuel drips rather than atomizes.

Even with elaborate systems of electric chokes, manifold thermostat coils, and preheat tubes, engines barely had a usable fuel-air mixture when cold. The design goal was to get them to start when cold, not to run well.

Computerized fuel injection fixed all of that. Extreme temperature? Just look it up in the table? At 13K feet? Adjust according to the table. Sudden throttle movement? Another table adjustment. Got it slightly wrong according to the oxygen sensor? Save the adjustment for the next time.

 

[KrisZ]

I have remote starters on both of my vehicles. Best thing ever for cold winter starts. I start my cars just before getting dressed. If it's really cold outside and I'm traveling with my whole family, the cars get idled for 5-10 minutes. I couldn't care less about how my vehicle feels about it, I want comfort and clear windows.

 

[dblshock]

I start and go here.

 

[gathermewool]

Originally Posted By: Vern_in_IL
Nissan owners manual says wait 30seconds before putting vehicle into drive.


Under all conditions?

 

[bullwinkle]

Not with an IDI diesel, it takes at least a minute or 2 before the 6.2 or 7.3 can make enough power to do anything but creep. I will nurse them around the neighborhood, but there's no way they could handle a full throttle interstate on ramp in the first couple minutes!

 

[Merkava_4]

You guys ever get a car pull in front of you with a cold engine that has just left the driveway ?

Their catalytic converter hasn't lit off yet and you're sucking in all the fumes through your dash vents.

 

[Garak]

Originally Posted By: gathermewool
Originally Posted By: Vern_in_IL
Nissan owners manual says wait 30seconds before putting vehicle into drive.


Under all conditions?

Yes, my G37 says the same thing.

 

[gathermewool]

Originally Posted By: Garak
Originally Posted By: Stewie
What do you guys think?

That was clearly written one year before Ontario's latest cold snap. If he wants to dress up like a snowmobiler and drive off in 30 seconds in -40, all the while avoiding breathing in his interior until the engine gets some heat into it, all the power to him.





I've never experienced -40F/C temps, so take this with a grains of salt: I typically dress for the weather, which means that driving all cozy in a car in my winter coat, beanie, scarf and gloves is a lot less daunting than being out in the actual elements. I have no problem hopping in and driving off, so long as the air is dry enough to literally absorb all of the moisture in my breath before it even reaches the windshield.

I try to be nice to my vehicles and typically don't even use the heat if it's above freezing, because I don't feel I need it, but the thing is a machine, so if it's -15F, I'll immediately crank the defrost to high after a mile or two, both to put some more load on the engine, but to also put whatever heat the coolant has absorbed into the cabin, as quickly as possible.

Also, another thing that has been brought up, that is definitely a gray area, is how the car performs. >0F the Civic seems to shift and do everything normally or maybe only a little sluggishly at firsts; however, unusual noises and shifting behavior at well below zero occasionally convince me that waiting 1-2 minutes idling before heading out might be in order.

I also idle the engine to warm up a little if there it's freezing-raining, the air is very moist, or any other condition that might require dry, warm air to maintain visibility.

 

[gathermewool]

Originally Posted By: Merkava_4
You guys ever have a car pull in front of you with a cold engine that has just left the driveway ?

Their catalytic converter hasn't lit off yet and you're sucking all the fumes in through your dash vents.


There are several vehicles that idle for extended periods before heading off-shift where I work, and they all stink, even after the wait. Some, mostly trucks, stink upon arrival.

I do take your point, though, and agree that cars typically put out more emissions while cold than after fully warmed up.

Originally Posted By: Garak
Originally Posted By: gathermewool
Originally Posted By: Vern_in_IL
Nissan owners manual says wait 30seconds before putting vehicle into drive.


Under all conditions?

Yes, my G37 says the same thing.


Interesting. I wonder what the logic for waiting 30 seconds on a warm day is. At that point, everything that needs to be lubed, will have been lubed for 29.9 seconds.

 

[chefwong]

There is now right or wrong answer to this....as sometimes conditions sorta dictate it. For example, 3 cars in the household. 1 of them has to sit outside the garage.

It takes at least a solid 3 miles for it to generate any heat for the blower to start with even medium lukewarm air. If the car that sits outside is the one in which the toddlers are riding in that day, it will sit idling while we shuffle to get them ready to get some creature comfort heat in the car.

 

[29662]

If its warm out(i.e. I dont need a jacket), I will let my truck idle for about 30 seconds while I put on my seat bealt , adjust the radio etc. If it's cold, I will let it idle for a few minutes while I get my coffee and "stuff" for the day. Wife does the same thing.

On my motorcycle I will usually let it idle until the coolant temp gets to about 120f or so. Although it's fuel injected it runs much better once the engine is up to temp. Plus the vtec wont engage until the temp hits 159f.

 

[Sonduren]

As soon as I turn on the car, I make sure I am all settled to drive and begin driving very slowly keeping the revs low until I hit operating temperature.

 

[IndyIan]

Originally Posted By: Garak
Originally Posted By: Stewie
What do you guys think?

That was clearly written one year before Ontario's latest cold snap. If he wants to dress up like a snowmobiler and drive off in 30 seconds in -40, all the while avoiding breathing in his interior until the engine gets some heat into it, all the power to him.

Yes, fuel injection systems run much better in the cold than carbs did. Carbs did start better, but keeping the engine running sometimes could be a challenge. One cannot argue the point that one can actually get in and drive a fuel injected vehicle immediately. That's true. But, if it's much below -15 C, there is going to be a slight warmup period, especially if I've had the vehicle off for many hours.

Fortunately for me, the G37 generates a lot of heat in very short order.

Originally Posted By: Shannow
demarpaint, given that I doubt anyone regularly drives a carbed engine these days....

Well....

My F-150 was the last year of carbs for that model.

A trick you can use to drive off earlier in extreme cold is to run the defrost on full cold to keep the window clear until the engine warms up and then switch it over to heat slowly. I find in the mornings anyways I'm active enough to be reasonably warm myself and can stand a few minutes of cold car time until it warms up. Over the years saving 50 cents a morning for a few months adds up.

 

[demarpaint]

Originally Posted By: IndyIan

A trick you can use to drive off earlier in extreme cold is to run the defrost on full cold to keep the window clear until the engine warms up and then switch it over to heat slowly. I find in the mornings anyways I'm active enough to be reasonably warm myself and can stand a few minutes of cold car time until it warms up. Over the years saving 50 cents a morning for a few months adds up.


The operative words are full cold. What a lot of people do is put the defrost on full hot while the engine is warming up and actually slow down the engine from reaching full operating temp.

 

[supton]

I wish I could engage recirculate while on defrost. I don't understand why it's usually blocked--ok, I do, but I'm quite able to work the controls. What I'd like to do, when it's well below freezing and I have hard ice on the windshield, is go back inside for a few minutes. And/or clean the car off.

Anyhow, apart from snow removal duties, unless if it's below 10F or so, I turn the key and go. 10F and down, if it's first thing in the morn I go back inside for a few minutes. If I'm at work though I just go, since I'm not walking 100 yards back indoors.

Letting the car idle does help with putting heat into power steering and trans fluid. But not lots of heat. And does nothing for my RWD/4x4 diffs.

I also try to dress for the weather, and make the kids do so also. I mean, what if we hit the road and break down, or have an accident? Won't matter how warm the car was--it'll be a cold walk. Better be prepared.

 

[Schmoe]

phooey.....with all those dissimilar metals in an engine and all with different thermal expansion rates, do you really want to just crank up and jet? I'm a firm believer in letting things warm up first....do you ever get out of bed and start running once your feet hit the ground??

 

[Pontual]

I let it fast idle for 40 seconds (in summer) to warm up the pistons so I get less blowby under load and keep my oil uncontaminated with excess fuel. Then I go slow to normally. Winter, I let about 1 minute.

It is under load, that the blowby and unburned fuel really go past the rings and cold piston head (still smaller and conic, right?) and skirts.

 

[holdorf333]

On a cold day, I'll let it warm up so I don't kill myself because of windshield fog. I think it's prob better to get it going sooner than later and take it easy on everything the first 5min or so, but gas "wasted" clearing the fog is gas well wasted imo.