TL Peak N

Just was wondering if anyone has measured the usage of fuel when a 3g '04 is idling at start-up per hour. I normally let my car warm up for about 15 mins (with an electric start) in the winter cold to de-ice and warm up the interior. How long could a gallon last at idling? Just wondering.

LaCostaRacer

I would estimate that you burn about .8 gallons an hour idling. Here's how I came up with this estimate:

given: If I go 70 MPH I can get about 30MPG- the tach is around 2200rpm? at that speed. This means I burn just over 2 gallons an hour cruising at that rpm

idling: your tach is in the 7-800 rpm range. 800/2200 * 2 gallons => .72 gallons

I hate cars

You've also got to figure at 70mph you're using about 40hp worth of fuel where at idle it's somewhere around 5hp.

I used to have the figures for idle fuel consumption but they're long gone. Going by memory those figures are pretty close.

SouthernBoy

It would be better for your engine if you didn't do this. Much better to start it, wait for perhaps 30 seconds, then drive slowly (around 25MPH) and carefully for about a mile before easily getting up to speed. Letting your engine idle for longer periods of time can increase condensation in the engine and crankcase along with more acids from less efficient combustion, and can shorten the life of your exhaust system.

Your biggest problem with starting it then driving off is ice removal. So try this. Get a bucket of cold water and splash it on the windshield. This can help dislodge ice. Also, don't use your defroster button to blow air on the windshield, use the manual mode with the highest fan speed and highest temperature setting. This won't engage the A/C. Then turn your sun visors all the way down to trap air at the top of the windshield. This will help melt the ice more quickly.

wonton

+1

Jesstzn

See bold above. Sorry JMHO

I hate cars

The warm the engine up vs drive immediately debate.

For me it's simple, it depends on the commute. In the morning I leave so early I'm practically the only car on the road so I can accelerate super slow and maintain a steady state 45mph for 5 miles or so before I hit the highway at 55mph. In this scenario I let it idle for 45 seconds and drive away. Steady state 45 mph is very, very little load yet it warms the engine up much faster. I also put it in manual second from the very start. This way when I'm driving through the neighborhood with thick cold oil my rpms never go past 1,800rpm and I don't worry about the filter bypassing. I also manually upshift much quicker than the computer does to keep the rpms low. Remember, I may take 30 seconds to rearch 45mph since I'm the only one on the road.

Leaving work I hit the highway immediately pulling out of the parking lot. In this case I let the water hit full temp first because I usually have to go 3/8 or more throttle when pulling out.

I think Southern Boy is right for 90% of the commutes out there. Keep in mind that while the water temp gets up to full temp in a couple minutes the oil takes about 20 minutes and much, much longer if ever when idling. This is the crankcase condensation you have to watch out for. If anyone wants to do a test, see how much more quickly the MID says to change the oil when you let it idle for extended periods on a cold start even though the mileage will be the same.

He's right about the exhaust system not lasting as long with extended cold idling. One of the byproducts of combustion and the chemical reaction in the convertors is water.

Really, the best solution for the short tripper is a weekend trip for at least an hour to burn off the condensation and acids from the short trips.

With all that said I'm guilty of letting the car sit there for 20 minutes when I was in Flagstaff with a morning temp of 12F.

01tl4tl

the fuel system goes to full rich for cold start and really needs some forward car motion and actual temp in the engine to go to normal lean setting- where the gas savings are.
Sitting to warm up is bad news, the alternator is at low rpm and the heater etc is on high demand

If you do frequent trips of less than 10 miles.. acura says at least once a month take it on the freeway for 45+ minutes
It takes that long to fully dry the exhaust and moisture everywhere
The fluid in ps needs a good useage to dry moisture from it

jisleyjr

To the OP. You should be able to figure this out if you do some mileage tests. If you have a normal schedule that you drive you should be able to have one tank where you do the idle'in thing, and the other where you just start the car and go. Track time of idling and compare the difference in mpg, or if the distance is the same you can just figure the difference in gas needed each time to top it off, then based on the total idle time you have your answer.

IMO idling the car every morning for more then a 20 seconds is a waste of gas and is more wear on the engine. When the car is cold just take it easy. It was -25ish this morning and i only let the car idle long enough for me to pull the garbage can to the street.

Put on a hat and some gloves, you'll live.

I hate cars

I agree. The only plus here is that the TL goes into closed loop feedback mode very quickly after a cold start. It's still in an enrichment mode but not as bad as many other new cars and all old cars (since it's metered and not a guessing game) that can take over 10 minutes to go closed loop.

YeuEmMaiMai

1. start car
2. scrape windows if needed
3. wait 30 seconds to a minute
4. drive away slowly

car gets much warmer quicker

SouthernBoy

Let's just say our ideas differ and we will just have to agree to disagree. However, if the trip is short, really short, then I do agree with you in that it won't really buy you much.

As for splashing cold water on the windshield, I would have thought anyone of a mind to do this would have enough sense NOT to do it in really cold temperatures; an assumption on my part. It does its work in moderately cold air and does it quite well. Definitely don't want to do it early in the morning when it's 22 degrees outside.

SouthernBoy

If one's commute is really short, say less than three miles, there is no reason you can't take a longer more round-a-bout route to get to work. No says you have to take the shortest way. I used to do this pretty often simply because I love to drive and it would add about another fifteen minutes to my going home time.

In my last job, I was 17 miles from work, yet in the morning, it took me 45 minutes. And that was leaving home at 4:45am! The reason is because I stayed off of the super highways because I am anal about my car and don't like stones thrown up on the paint and windshield from other cars at speed. So I went through town (Manassas) both on the way to and from work to avoid this. Nice little ride and my engine got thoroughly warmed up.

01tl4tl

The AC is tied to the defrost because it does a good job of temperature increase gently to the glass, and drying of moisture from inside the car.

It also exercises the a/c so it will still work next summer- otherwise the seals dry out and fail

People who dont use the defrost in winter should run AC at least 10 minutes per month or expect big repair bills

TL Peak N

I normally let my car warm up to heat the insides and/or de-ice the car for about 5-15 mins in the winter cold frost/ice snow, because I really like driving comfortabily without my heavy coat on, I put it in the trunk.. I have't noticed the MID changing about oil changes. I Normally receive 6700 miles before the MID requests a change of oil at about 15%. I drive about 3 miles to the highway then 25 miles to the Airport, USAIRWAYS. I'm sure that I blowout the condensation from the exaust system fairly nicely on the highway going and coming. Maybe I should just get my garage cleaned out of MY 89 Buick Reatta and parts, add a heated/cold systems to keep TL CUPID warm for many projects to come. I'm a newby to the VTEC and I love her. You Guy are something else with all of your knowledge and helpful insights that work well. What a club and what a wonderful team we have here. IThank you. I know that I have a few beer's with many names on them for some of you. CHEERS TO ALL of you ... THANKS

SouthernBoy

This is true, but I am guility of not doing this like I should simply because I forget - and I know better, too.

As for using the A/C via the defrost button, the only time I do this is when there is the danger of my windshield fogging up. Otherwise, I use the manual vent direction setting and manually set the temperature to do the work. This works great.

But you're right. We do need to exercise the A/C during the off seasons to prolong its life.

alexSU

iTrader: (3)

so how long do i have to drive to warm the car up before i can give it full throttle? is 15 minutes enough?

there is a nice stretch of open road on the way to work where i can almost top out 3rd gear. it's like 7 miles from my house, about 15 minutes of driving before i get there.

I hate cars

15 minutes should be enough to get the oil to full temp or close enough. If I know I'm going to be hammering it I'll progressively drive it harder and harder the longer it's been running to get things heated up quicker. With the 20wts you only need 170 degrees or so instead of the normal 190-200.

alexSU

iTrader: (3)

^Thanks!

thisaznboi88

iTrader: (7)

just remember from a cold start to warm up the car runs rich and takes a lot more gas. But that pretty interesting.

princelybug

iTrader: (16)

OP, to answer your question: During idle, one gallon of fuel will last you a LONG time, but I don't know exactly how long?