It's my understanding that higher RPM equals higher fuel consumption. So, if you're going down a steep hill, using engine braking, and your engine is at 4000 RPM, is it needlessly guzzing gas? Or, does gas only flow to the engine when I press the gas pedal?
I'm asking in reference to a 2003 Honda Civic, if that matters.
2006-11-27 09:51:24 · 18 answers · asked by Kramer 1 in Cars & Transportation ➔ Other - Cars & Transportation
I dont think it would "gussle" gas going down hill , you probably would not even notice the difference in mpg since its not under a load. You would be better to wear out your brakes than to wear out your engine though.
2006-11-27 10:14:54 · answer #1 · answered by Thomas H 4 · 0⤊ 0⤋
I love a good discussion. As was mentioned many times above, the only time the fuel shuts off on an '03 Honda is when you turn off the engine. Only Gas/electric hybrid cars like the Toyota Prius may indeed completely shut off the gas engine when driving downhill. Your engine-braking downhill engine speed of 4000 rpm means that the engine is getting dragged along by the drive train as gravity tries to accelerate your vehicle. So even though engine load is light, it is still running at 4000 rpm and drawing fuel on every one of those rpms. What was your engine speed on the uphill slope? It was probably less - much less.
2006-11-27 19:00:41 · answer #2 · answered by db79300 4 · 0⤊ 0⤋
It depends! Most modern FI engines don't burn any fuel when you're in gear with no throttle. The engine only starts injecting fuel when engine speed is low enough that it would stall otherwise. Older cars won't be as advanced and will always inject some fuel. On your car you could try turning the ignition to accessory whilst moving (watch you don't activate the steering lock) and see if it slows down more sharply than if you took your foot off the gas - if it does it means a small amount of fuel is being injected.
2006-11-27 18:16:34 · answer #3 · answered by Anonymous · 0⤊ 0⤋
if you are engine braking then it may use a bit more but not much...fuel consumption normally only increases as you accelerate more. Using the engine to slow you down will normally not increase fuel consumption...it will however save on your brakes. Just don't let it rev so hi...4000 rpms is rather hi for slowing down...if the engine is reving that hi...shift to a higher gear or use the brakes...try to keep it under 3000 rpm for this application.
2006-11-27 18:00:39 · answer #4 · answered by Kenneth S 5 · 0⤊ 0⤋
To the morons saying it doesnt burn any fuel, sorry to say, but you're wrong. Been a mechanic for a while, and trust me, for an engine to run, regardless of the year it was made, it HAS to burn fuel. when coasting down hill it will be less, best bet when rolling downhill, depending on the grade of the hill, shif it in neutral, and use brakes to slow when needed. If its a manual trans, just hold in the clutch. Like I said, depends on the greade of the hill. If its real steep, may have to keep it in gear and suffer through burning a little more fuel.Unless you're real anal retentive about tracking your fuel mileage, you probably wont notice.
2006-11-27 18:37:06 · answer #5 · answered by brassknuckle_mayhem 3 · 0⤊ 1⤋
It always uses gas if running, even at 500 rpm's, and yes it uses more with engine braking, but safer on long steep hills than riding the brakes.
2006-11-27 17:59:21 · answer #6 · answered by Papa John 6 · 0⤊ 0⤋
Most modern cars are 'smart' enough to know when you are simply coasting in gear and they will cut all fuel flow to the engine to save gas. Once you get back on the gas again it starts to deliver fuel again very quickly. So no, it's not using any gas at all when you are coasting.. Older cars might not be as advanced and the engine would continue to deliver whatever amount of fuel it needed to idle, which isn't really that much, but it's still more than none at all!
There are aparently alot of people who don't know about this.
Check out this link.
2006-11-27 17:54:33 · answer #7 · answered by Louis G 6 · 0⤊ 2⤋
if you are going down hill with your foot off of the gas pedal and the rpms are at 4000 the engine is only using as much fuel as it would at idle.
2006-11-27 17:58:37 · answer #8 · answered by vw tech 3 · 0⤊ 1⤋
If the engine is running, it's burning gas. Acceleration causes it to use more gas, but either way, you are burning gas. You can actually run out of gas sitting with the transmission in park. The engine has to have gas to run... period.
2006-11-27 18:00:39 · answer #9 · answered by ihave5katz 5 · 0⤊ 0⤋
in answer to your question,most fuel injected vehicles are designed to shut down fuel or injectors on deceleration to a preset rpm .example 1500 rpm,then the computer will command fuel to be introduced to prevent engine stalling.this works with a number of inputs from various sensors,to the computer.
2006-11-27 18:03:43 · answer #10 · answered by samuel b 2 · 1⤊ 0⤋