How much fuel does idleing use?

[Snoranger]

I can’t tell you how much fuel a 2.9l uses at idle, but I can tell you this...
I bought a ‘93 Thunderbird parts car (3.8l) that I wanted the fuel tank out of. It had a full tank. I started it up at noon one day and left it running all night at work. The next day after work (4:30, total of 28.5 hours) it had used a little more than 1/4 tank.

 

[racsan]

many things contribute to bad winter fuel economy, (1) engines are most efficient at a certain temperature, it takes longer to reach 195 from 0 degrees than 80 degrees ambient temperature. (2) winter blend fuel, Im uncertain if winter blend fuel exists in every state where it drops below freezing but this fuel formula is less efficient than fuel available the rest of the year. (3) driveline resistance, oil everywhere else is cold-power steering, axle,transmission. thick & cold oil adds resistance and causes more fuel useage. Im sure theres more but thats what directly comes to mind. Idling? sure its going to use some fuel & contribute to “bad winter fuel mileage “ but I doubt its that much. My winter beater (2006 hhr chevrolet 2.2) gets 26 in the summer, I just got gas this morning and milage checked out at 16. Yes it idles every work morning, longer than the commute it takes. The escape goes from a summer mpg of 21 to 18. I try to keep the ranger parked during the winter, mainly to keep it out of the salt bath and also its never been known for great heater output. That 2.3 gets 21 summer and about 15 in the winter. (sure 4.10’s play a part, but I didnt build my ranger for fuel milage either)

 

[scotts90ranger]

Yeah, 4.10's sure help the drivability but the mileage sure is lower than I remembered... back in the day with 25" tires and 3.08 gears the '90 got a peak of 28mpg, and a low of 23mpg with 28" tires and 3.73 gears after E10 gas started... I swear that thing had more low end than this '97... or I just drove different and wasn't used to anything different? I drove it on the same commute with 4.10's and 31" tires at I think 19mpg... whatever, the fuel savings has paid for the '97 over the V8 Explorer

 

[sgtsandman]

I didn’t pay attention today with the morning commute air temperature being in the mid 20s but the last couple days with the real low air temperatures, the engine didn’t break 188 degrees with a 195 degree thermostat. So, it technically ever got to full operating temp. Warm enough to cook me out but I don’t think the thermostat ever opened and ran in by pass mode for the whole 30 minute drive.

 

[Eddo Rogue]

Back in early Y2k's, My college apartment neighbor had a VW Passat. He was from Indiana, told me he once drove to a music, and after partying all night, crawled into his car and slept for a good 8+hours with the engine running and air conditioning cranked. my first question was how much his fuel gauge dropped, to which he replied "not much". It had a turbo V6 if remember correctly

 

[Eddo Rogue]

What I save in doing my own maintenance, minor repairs, and having no car payment leaves plenty of budget for gas and beer money. oh and minimal insurance premiums helps too....

 

[19Walt93]

Idling for a few minutes to warm up the engine reduces engine wear, nothing in an engine fits properly cold. Cold weather hurts mileage because all the fluids thicken up and cause drag, snow tires have more rolling resistance so they hurt mileage, studded tires are even worse, and alcohol polluting the fuel hurts mpg all year long. We got a ton of poor mileage complaints when remote starts were introduced. I explained to a Dartmouth professor that his Explorer got zero miles per gallon when it wasn't moving, he insisted it had to be better than that and argued with me. He made more than triple what I did and couldn't understand that zero movement with the engine running meant zero miles per gallon. Many of our customers would stop in to visit with the owner or salesmen, one F150 owner let his truck idle in front of the building for 45 minutes while he and the owner talked about hunting- then complained of poor mileage. It took a while to convince him to try shutting it off while they visited for a week to see if the mileage improved and he doubted it would help. He never admitted I was right but he didn't bring it in for diag, either.
New vehicles have a start/stop feature that shuts the engine off when the vehicle stops and restarts it when the accelerator is pressed, supposedly to save gas. Keep in mind, the price of replacing starters and batteries isn't counted, except by the owner who's paying for them.

 

[PetroleumJunkie412]

Dartmouth professor

Why in the name of the Lord would you presume intelligence?

 

[don4331]

New vehicles have a start/stop feature that shuts the engine off when the vehicle stops and restarts it when the accelerator is pressed, supposedly to save gas. Keep in mind, the price of replacing starters and batteries isn't counted, except by the owner who's paying for them.

The numbers the EPA quotes is the start/stop feature will save you a tank of gas a year in normal driving; Ranger gas tank is 68 liters, regular it $1.399/liter = $95. Starter from Tasca Ford is $97.90. Ford warranty covers starter for 5 years, so they expect them to last at least that long (given Ford want >99% to make it to end of warrantee, it should be failing the day after). So, by EPA numbers, I'm at least $250 ahead ahead (OK, I do my own repairs, so I don't count that shop costs, but the average individual should at least break even).

You can dispute the EPA numbers, but those are what bean counters/engineers are working from when they developed the system.

 

[RonD]

I don't care for auto stop/start but I can tolerate it, as long as I can disable it when I want
It wasn't ever added for fuel savings

It was to meet idle emissions testing

$100 for the starter and $400 to install, so the 5 years works, lol
So its even money as long as gas prices stay the same, but that's not likely, gas will go up, and faster than the price of starter motors, lol

I turn it off in heavy traffic where the idiots in front of you need to move that 1/2 car length at a time
And at stop lights..............where the heck does that 1/2 car length come from, and some times repeatedly
The lights red, the length of vehicles stays the same, where the heck does that pull forward 1/2 a car length come from?
There can't be that many people out there with bad depth perception, can there?

 

[scotts90ranger]

..............where the heck does that 1/2 car length come from, and some times repeatedly
The lights red, the length of vehicles stays the same, where the heck does that pull forward 1/2 a car length come from?
There can't be that many people out there with bad depth perception, can there?

This day and age, cell phones... I'll be stuck in bumper to bumper traffic, the first 3 seconds the light is red 1.5 cars will go through, by the end of the light traffic will be moving 15mph with 75' gaps between cars...everyone complains about traffic but don't want to put their dumb phones down or maybe watch 2 cars in front of them instead of the car in front of them... like today, I was stuck behind a minivan likely with a 3.3L engine (caravan), they were a slug off the start then accelerated up hill... I was towing a few hundred pounds of pallets with 100hp, accelerating up hills isn't a feature I have... It really irks me when my underpowered junk is waiting for sports cars to get out of my way too... like the Subaru RS that wouldn't go over 45 in a 55...

 

[85_Ranger4x4]

I need to time it sometime, I am pretty sure my 302 will idle for a good 5 minutes on just the fuel in the bowls.

Seems to take a half hour for the darn thing to drain the carb whenever I need to pull the carb for something.

Kind of a how many licks thing, it doesn't take long before I end up revving it to get the process moving along a little faster.

 

[gaz]

Rusty,

I was taught that 20 minutes at idle is approximately the same as 1 hour at posted highway speed; so I expect to use whatever my vehicle needs to drive 60 mph, for an hour, while idling for 20 minutes.

Both mine have always warmed up slow but I have adapted bar EMERGENCY situations, drive only after the engine is to normal temperature. It is the most efficient when at normal operating temperature and that has offset any fuel used to get to it.

I also have a hotrod, if I make that engine do anything more than warm up before making power it drinks gas to remind me. What I have come to understand is that the fuel mapping is the worst between 0-35mph; it's a combination of more changing speeds and power needs, after 35mph, a gradual aceleration up to needed driving speed is most efficient. Often times, gradual is dictated by necessity.

 

[RonD]

I want the technology to catch up to my great ideas....................oh wait its here

I want all vehicles to have dash cams with distance readouts, for the vehicle in front of you
When a light changes to green if I can get within 1ft of that car in front of me, he/she OWES me $5, from license plate
That will get people to pay attention, paying $50 a day to be on their phones, tickets just don't seem to work
And its like a 2nd job, $50 day extra if you find 10 idiots
I would have made a few hundred today, lol

I really can't wait for full automation

 

[fastpakr]

Rusty,

I was taught that 20 minutes at idle is approximately the same as 1 hour at posted highway speed; so I expect to use whatever my vehicle needs to drive 60 mph, for an hour, while idling for 20 minutes.

Both mine have always warmed up slow but I have adapted bar EMERGENCY situations, drive only after the engine is to normal temperature. It is the most efficient when at normal operating temperature and that has offset any fuel used to get to it.

I also have a hotrod, if I make that engine do anything more than warm up before making power it drinks gas to remind me. What I have come to understand is that the fuel mapping is the worst between 0-35mph; it's a combination of more changing speeds and power needs, after 35mph, a gradual aceleration up to needed driving speed is most efficient. Often times, gradual is dictated by necessity.

Am I reading correctly that you believe you're using three times the fuel while idling as you do running on the highway?