5.7 idle fuel consumption per hour?

Does anyone know the idle fuel consumption per hour of a 5.7?

Use case: Snowstorm, tornado or mudslide. You're stuck on the highway inside your Tundra and you run the engine to keep warm and listen to the radio. Or you get stuck on the trail in a storm and the only thing you can do is sit and wait.

Yes, the cats can get super hot and burn out with excessive idling, but it's better than freezing people.

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I have seen some napkin math online (sorry, it's in liters):

Engine displacement in L * 0.6 = fuel consumption per hour

That would mean a 5.7 would use 3.42 L per hour.

So a 130L tank, assuming you get stuck when it is completely full, would last 38 hours of idling.

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Question: Does anyone have a more accurate fuel consumption per hour?

 

If anyone can measure the mass airflow at idle you can calculate the fuel consumption but it’s rough. You need to consider the increased idle speed for heater and other accessories.

fuel (kg/hr) = MAF (g/sec) * 3.6/14.7

 

@Jeff_5_7

 

My scanguage says .44gph at idle

.8 with a/c on

 

I’ve seen scangauge data indicating about .5-.6 gph.

 

Is ScanGauge data for instant fuel generally accurate? I know it wasn't on my old Taco.

 

That's a pretty sizable difference in an emergency situation.

 

Dunno

it’s accurate when it tells me how much fuel I’ve used before I fillup

 

I checked some old logger data I have and was seeing around 7.8 g/sec which means 1.91 kg/hr. That equates to roughly 0.4 gal/hr. This was at 1500 ft elevation.

 

You'd be halfway to your answer if you turned your truck on when you started this thread

 

My ‘06 sequoia idled at .38 gph

i remember because i thought that was a lot.

I miss that ride.

 

Start the truck and get sort of warm, charge the battery, turn off for 40 minutes, repeat. Hunger might get to you more than the gas issue!

 

I measured it directly from the injector on my 2007 5.7 Tundra. Read the data directly off the CANbus. Mine was burning 1.6 gallons per hour at idle.
I never played around with turning the AC off ect but I can.

I only logged about a minute worth of data (1900 ish samples) on startup. It was a 60 ish degree day in Texas. Avg. was 1660 micro liters per second which is about 1.6 gallons per hour.

At 70 Mph I Avg 4.75 gallons per hour burn rate so Avg Mpg of 14.7

https://www.tundras.com/threads/a-d...fuel-use-from-data-logger-instant-mpg.101602/

Reading some of these other post make me thinking my number could be a little high. I know it’s accurate however as this is the exact signal coming from the engine ECU. Might try again with the truck fully warmed up and AC off ect. People saying only .4 gallons per hour sounds kinda low for the 5.7 V8

 

Holy crap I hope that’s off.

 

It's as direct as a measurement you gonna get lol

Obviously a lot plays into factor here:
Cold vs warm ECT
Cold vs warm amb temp
Engine load via consumer draw
Etc

 

There’s always the chance the equipment or reading is off…. He says hopefully.

 

Where did he hopefully?

* reread it - He also did a cold start which I believe pulses injectors numerous times per cycle to help speed up catalyst heating.

 

“He says hopefully” meaning, “I hope”

 

I know what YOU said, I dont see where HE said hopefully.

 

This is why I love this site. Great data points and considerably more than my napkin math.

 

I spent most of my money on women, alcohol and motorcycles. The rest I just wasted on idling my Tundra.

 

Looking into this more now. There is always a chance I missed a unit or scale factor and the data could be off. This is the first time I have thought to look real deeply at it.

So far in my experience the data has always lined up well and made sense but I could have an error.

 

What a great idea to figure this out. I remember a ford ad from a while back with Mike Rowe where they did an MPG test and to visualize the gas used, they had these small transparent gas tanks mounted to the fuel fills riding outside each truck to track usage visually. Like a kitchen measuring cup.

 

Few different tests would be good, few different and a few of the "same".

I'm pretty sure the injector duty cycle on cold starts is two or three per to aid in cat heating.

 

Could be a factor of 4 based on everyone else’s reply of 0.4~0.5 gal/hr.

 

2 or 3%?

I just did some quick math researching that stock injectors flow 370 ish CC/min at 100% duty. That’s 5.8 gallons per hour for each injector at 100%, 47 gallons total per hour (100%)

If idle is 3% duty cycle I think that would be 1.4 ish gal/hr total

If this math is correct to get to a 0.5 gal/hr at idle the injector duty cycle would only be 1%

 

I heard from a trucker that his rig burned about a gallon an hour idling with the a/c on.

 

I pondered this....it only reads OBD data.

I don't know how it could be inaccurate?



side note...I accelerated @ 22GPH on the on ramp.....so there's that.

 

for the math folks...

this is at idle after a 25 mile drive, in park, no a/c...waiting for 5 dim-wits to figure out how to open a locked gate.


if you remove a metric-smidge for the blower drag...you could be just under .5 GPH

I attempted to put all the variables on the screen...IGN was a bonus.

also...on cold start up....1.6GPH.

 

I don't know but...when I had my '15 I got stuck going home from work in an ice storm, the drive was around 30 miles and took me about 8 hours. I'm guessing my top speed was around 35 MPH mainly in 2 WD with a lot of idling and going no where, I don't know if I ever shut it off. I started out with just under a half tank so around 12 gallons and had right at a 1/4 tank left. You do the math because I'm old, cranky, and don't give a rat's butt.