pros vs cons of warming up the car on a cold winter morning?

[gmcjohn]

Warm your truck with pride and a smile and look at the bright side I know my remote start shuts down at 24 min. As for global warming, the only hot air is from the dumb ***** in Washington. They screwed up the HVAC/R industry stole money with BS rules. Whats next "farting"

Funny that you mention that.. I heard that there are many environmentalists that point to methane (produced by the ***** matter of livestock) as a big cause of global warming. You know the same ones who are vegetarians and involved with peta are saying we need to kill more animals? damn ******.

 

[gtbigup01]

Total waste of gas, 30 seconds to a minute is all thats needed to get your oil circulating. Xsmn will not warm up until you start driving. IMO no harm done aside from burning gas just sitting. With the gas mileage we get, I would assume you'd rather be driving to burn your gas.

 

[rigo_jones]

With the gas mileage we get, I would assume you'd rather be driving to burn your gas.

uhmmmm... i wouldn't.....

 

[Eagle]

Not needed.

It is the slowest way to warm it up.

What I do is go out fire it up IF IT IS OUTSIDE THE GARAGE, turn on the seat heaters then come back in, make sure my son has his back pack etc, then we go out to the truck, get in, and drive away. On really cold mornings, I stay in tow mode for the first couple of blocks (keeps rpms up in the midrange instead of at 1500, turns off all the electronic slippage) and usually am warm enough to start getting heat (1/4 gauge) when I arrive at his school.

If it is in the garage, those 2-3 minutes are consumed by getting the Tahoe out of the garage, (open door, back out, unfold mirrors, close garage, get son in car, drive away.) And then I drive away at modest throttle inputs and rpm until warmed up.

 

[gtbigup01]

uhmmmm... i wouldn't.....

So you'd rather sit in ur driveway burning gas instead of enjoying your ride, even if it's just back and forth to work? Ok then, more power to you

 

[TunasTwins]

Just to clarify, when the engine is cold, more fuel is injected into the combustion chamber as the fuel can not completely atomize. This extra fuel is injected to ensure enough fuel will be burnt to create the required amount of combustion chamber pressure required to make the engine run, smoothly.
The PCM will command a richer mixture until the defined CLOSED LOOP temperature is met. Once the vehicle hits this defined temp, closed loop will begin and the PCM will adjust injector pulse width based on O2 sensor feedback to achieve 14.68 air/fuel ratio, which, is best for emissions..... Some of you may have experienced your vehicle runs great until it warms up and then it runs like crap-thats a bad O2 sensor most likely. I think everyone has hit valid points here. So....there are different things to consider: comfort-let her warm up; gas mileage-you're getting ZERO when its idling; wear and tear- 0-1 minute idle warm up and then drive like a grandma until you hit closed loop.
Heres some examples of what the PCM is commanding. This was from a 96 LT4 Vette.

 

[El Capitan]

LOL, that is super funny, if i lived somewhere like florida I would never have even thought to "warm up my vehicle"

---------- Post added at 10:48 AM ---------- Previous post was at 10:45 AM ----------



that is part of the info i read online and wasnt sure how valid it was, i didnt want to say anything about it and see if it was brought up here. Ill see if i can find the article again and post it to see what you all think

---------- Post added at 10:50 AM ---------- Previous post was at 10:48 AM ----------

heres the article I read that made me question running my tahoe for 15 minutes every morning:

Although you might think it’s easier on your car to let it sit and gently warm up, doing so is a bad idea for a number of reasons. Most importantly, it does indeed waste gas.

The vast majority of cars on the road today use electronic fuel injection. When your car’s engine is cold, the computer tells the fuel injectors to stay open longer, allowing more fuel into the engine to help it run cold. As the engine warms up, the injectors let in less fuel and everything returns to normal, so to speak.

The problem is, letting your car sit and idle is the slowest way to bring it up to operating temperature because it’s generally sitting in your drive at just above idle speed. And this method to warm up also invites other problems. Remember that modern cars are equipped with a multitude of devices to help them run clean, including a catalytic converter (sometimes three of them), a device in the exhaust system that works to burn off unburned hydrocarbons in the exhaust stream. A cold engine emits a far higher percentage of unburned hydrocarbons than a warm engine. Unfortunately, the average catalytic converter can’t process 100 percent of unburned hydrocarbons even in the best of times. Importantly, the catalytic converter needs high exhaust temperatures to work properly. Throw in a cold engine emitting a high percentage of unburned hydrocarbons, repeat several hundred times, and you can end up with what’s called a “plugged” converter. In a nutshell, the converter becomes overwhelmed and literally ceases to function. This won’t happen all at once but over time, the end effect is the same: poor mileage and significantly dirtier exhaust.

The best bet? Even when it’s 10 degrees F outside, start your car, let it run for 30 to 60 seconds to get all the fluids moving, then drive off gently. Your engine will warm up faster, your exhaust system will get up to temperature faster so the catalytic converter can do its thing, and you’ll use less fuel. Which is what you wanted all along anyhow, right?

If it's below zero outside, it would be a good idea to give the engine five minutes or a little less before you drive off into the frozen wilderness!

— Richard Backus, editor in chief, Gas Engine and Motorcycle Classics magazines

I really don't think he has any idea what exactly he's talking about. Well, moreso, why it does what he is talking about.

Engines will naturally run leaner in colder environments. Colder air is denser air. This leans your car out, which the computer will automatically adjust for(add/pull fuel, advance/retard timing, so on..) it will add fuel to basically put the air/fuel back where it is commanded to be.

They do NOT richen themselves up to warm up faster though. Most fuel injected cars will automatically increase the idle upon startup, until it is warm.
When you add MORE fuel, it actually has cooling properties and makes for very slightly cooler combustion temperatures. so: A car running rich will have a cooler combustion temperature. That's where most of the heat comes from on your motor; combustion heat. The other portion is from the friction of moving parts.

So say on a given 60* day your car is running a 13/1 Air fuel ratio. ON a thirty degree day, your car may WANT to run a 13.4/1 air-fuel(leaner). your car will add fuel and timing to make itself run the commanded 13/1 ratio(it will not richen itself past the commanded A/f), and the added/pulled timing will keep it from preigniting, detonation, knocking/pinging. The same amount of air is going inside, it's just denser therefore there is basically more USABLE air per cubic foot. the engine will add fuel for that extra dense air coming in.

Now if you just got bored and decided to say...add fuel for no reason via a tuner. A. it will richen it up past the commanded A/F and B. it will lower combustion temperatures slightly.
Some tuners will actually add fuel to richen it up just a little to prevent Short-term knock, which can allow them to tweak the timing just a little further(so they can tweak the extra power out of the motor.) Too much timing, and detonation can become an issue. too little can have adverse effects as well. The extra fuel helps cool things down and prevent pinging aswell.


Just trying to clear the air that the added fuel upon startup in cold weather is NOT to warm the engine up faster. It's to compensate for the dense air.

 

[Eagle]

no, he's right.
They do command more fuel (and a target ration OTHER than 13:1) under cold engine temps.

This is because it is LESS efficient when cold, as the tolerances are greater and counter intuitively, so are temps. Stoich has to do with EMISSIONS not power. Power is about 12:1.

remember, we are talking about engine temps. NOT air /external temps. What you are talking about is barometric compensation which happens constantly, we are talking about Open loop warm up, which only happens when the coolant temp is under 90C

Adding fuel PAST peak power decreases temps (which is why you see some turbo cars with 11:1 or 10.5:1 under boost and high rpm) due to heat absorption by the unburned fuel. Adding fuel up to ~12:1? Increases combustion temps.

with the prevalance of front widebands you can actually run closed loop (& non 14.7) under non steady state conditions. Otherwise the only time you are using the o2 sensor is under steady state (cruise).

 

[puckhead]

I have been letting mine warm up between 10-15 minutes. mornings are usually below 0 here. Im gonna try this 5 minute tops thing and see how it does. I burn alot more gas in the winter so anythings worth a shot for me

 

[JennaBear]

I don't let mine sit in the driveway to warm up, as the transmission fluid isn't getting to the gears. Rather, I don't go above 30MPH until I see the temp at a decent level.