^ that's true if it's off at a stoplight it can accelerate using only battery power as long as the load isn't too great. I don't think it shuts off until you come to a stop though, it's not smart enough to know if you're slowing for a turn or a stoplight.

 

Doesn't shifting between D and N while coasting increase your transmission wear?

 

Some people did buy their SUVs a long time ago while gas was still cheap.

 

why stop with this? Put car in neutral and just push your car around.

 

However it does not start like a conventional car, it has a smaller starter then most cars and I believe it feeds some fuel, and then the ignition kicks in on cylinders that have received the fuel and that usually starts it with minimal to no starter engagement.

 

fixed x2

 

Yeah, I really dig it when a guy tries to kill me right off the bat. Good stuff.

 

The guy drove a accord which he claimed he could get 50 or 60 mpg out of. In the news program they used a expedition(or explorer) and had the news guy drive it and he got like 10mpg then the guy drove the same route and got like 18

 

heres another new gas-saving craze... stay home.

 

 

wanna carpool?


You push and ill steer.

 

Jesus, I never thought I'd witness this but a lady in a Hyundai Tiburon did it in front of me today!!

 

Gas mileage wise, you're better off leaving the car in gear and coasting down. Most ECMs have a "fuel-decel-cutoff" where injector pulse width drops off to nothing a few seconds after you lift the throttle. The trans keeps the engine running. I don't downshift or anything, just coast down until about 11-1200rpm, then kick it out of gear and complete the stop.

I turn my car off if I'm sitting at a railroad crossing, or long light.

 

I know this is an old thread but I was searching for this exact post (go figure it was the last post in the very last thread of seaching) with a question that's bugging me.


If in my 6SMT I'm coasting IN GEAR, foot OFF the accelerator; and if the car uses no gas say, above 1,200 RPM, then why does the car sound like it's running? I understand how the momentum keeps the engine turning (I'm a master at push starts) but don't you need combustion to hear the sound of the engine through the tail pipes? I'm just trying to figure out how the car SOUNDS like it's running without any fuel being combusted

 

Actually, the car is using fuel when the engine is on, regardless of car speed-- the engine is just idling when coasting.

The engine sound should be the same as at idle, but you'll also get transmission, road and wind noise as the car is coasting.

 

WTF? Why wouldn't it use gas, it is running?

 

Hahahaha

 

You're better off using cruise control. Newer cars use different forms of cylinder management to save gas. Acuras included.

 

Because its using cylinder managment to alternate shutting off different cylinders but not the entire motor. It also alternates the shut off so you don't have any buildup in the motor.

Honda Worldwide | Technology Picture Book | VCM

Check the URL above. It doesn't use fuel since it suspends the engine mid cycle. Plug in an OBD II reader and see what happens to the fuel rail when you're off the throttle. Fuel is shut off completely under decel.

 

SurfingScotty has a 3G TL-S, which did not have VCM (Variable Cylinder Management).

 

It may not the exact same system that's employed but if you look at the short term fuel trim when the car is coasting or cruising there is no fuel flow detected. I'm not entirely sure what they use for the TL but it is one of the reason's why the real time economy systems show a huge boost in economy when you're off the gas.

 

I'm pretty sure fuel is entirely cut off while coasting above a certain rpm in modern cars - carburetor'ed cars would be using fuel while coasting.

 

A 3G you say

 

This is what I thought but there is a lot of discussion on the net saying that there is 0% fuel being injected into the cylinders during deceleration/coasting while in gear. But I disagree, with real world experience:

My motorcycle's starter died. Until I could fix it, I had to park on hills. I would simply coast in neutral until a suitable speed was obtained. I would then let out the clutch while in 2nd gear. The whine of the motor turning over could be heard until combustion (finally) occurred, about 2-3 seconds depending on clutch position, speed, and hill grade.

It's easy to tell the difference on the bike because I have straight pipes and the engine thunders to life when fuel is combusted but is nearly silent when NO fuel is combusted. Seeing how both my car and bike are fuel injected, I don't see how there would be a difference.

I appreciate the replies but I'm still looking for a scientific explanation as to how the engine isn't burning any fuel in my Type-S upon coasting in gear.

 

Called Deceleration Fuel cut off or DFCO for short.

as stated, the computer shuts off the injectors above a certain RPM with the car in gear

we know this because we've read fuel tables with an OBDII reader.
most modern cars have this feature.

 

 

If you care this damn much about not burning gas, ride an effing bicycle. Jesus

 

Que the ignorant child who is unable to comprehend the discussion to chime in and state his non-contributing opinion:

I'm not overly concerned with fuel savings, but rather educating myself on how this is possible and how it works. Education is not a bad thing, "CJ".

 

Adding something like this to the list of all the other things I have to worry about in a given day seems absolutely ridiculous.

 

So don't worry about it. Browse the site for things that interest you.

 

 

Thanks, Justn. How you found this.....beyond me.

 

/thread.

 

Okay I am still not convinced. Theoretically, if gas is stopped, wouldn't the car lose power steering and power brakes, just like if you ran out of gas while driving? Again, just trying to understand.

 

Your engine isn't off. Gas is not being sent into the motor. Your pistons and drivetrain still have inertia and the parts are in motion. So you get the same effect in both cases, engine braking. Your accessory belt is still driving every hydraulic system in the car.

 

Also when you run out of gas, everything works until you slow down to around 5-10 mph. At that point you aren't rolling fast enough to keep everything moving.

 

anything made since the late 1990's/early 2000s has fuel cut and this is the easiest thing to verify if you have a data scanner as you can actually SEE the injectors turn off...until the RPMs reach a predetermined set point at which point you will see the injectors start to pulse again... most likely engine noise you hear is the mechanical noise plus the air being sucked in, being compressed and then spit out the exhaust

 

The engine is a giant air pump. Even when off gas coasting the pistons and valves are opening and closing sucking and blowing air in and out of the cyls which in turn is still rotating the crank driving your ps steering/ac etc...

 

Thanks for the explanation, guys. I appreciate it. It's nice to know there are still guys on here willing to explain things to each other and not just post stupid-ass comments. It really is time consuming to have to read through all the bullshit replies to find the solution to your paticular issue.

 

^i viewed it as you wanting to understand and not because you cared about gas mileage.