Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - What's better on hills: DWL or Pulse up, Glide down?

Whoops · 05-12-2008, 06:56 PM

You seem to have some presumptions and comments which I would like to make sure you are aware of, prior to my feedback on my experiences, in my car.

When you are commenting, you seem to presume that you are in as high a gear as possible, going up hill, that you are able to maintain your speed and with a throttle opening which is less than 70-80%. Your question is further really restricted by the fact your car has a wide band oxygen sensor, but your question is about what seems to you to be conflicting information and which you have not been able to clearly discern an absolute answer to, for your car.

Presuming my understanding of your presumptions is correct, I am offering this. I am driving a 89 Honda Wagon, 5 speed. At one time I had a voltmeter wired into my oxygen sensor, which is narrow band. What I found was that on my car it would stay in closed loop, monitoring the oxygen sensor, until about 80-85% throttle. At that point, it would go into open loop and the oxygen level would decrease substantially.

If I can keep my speed up, keep the car in 5th gear and keep the throttle below 80% or so, then I use less fuel. However, if I have to drop down a gear or increase the throttle beyond closed loop, then my mileage goes down, drastically.

Consequently, where you are looking for a hard and fast rule, their are probably not a lot. However, if you can keep it in leaner burn mode and you can keep your rpm down, you are going to get better mileage than if you can't. Whether you can, what speeds you can, whether you can keep it in 5th, how steep the hill is, how long the hill is are all subjective issues which are largely only relevant to you, your car, where you are driving and the conditions.

I would focus more on trying to keep the your engine in more of it's lean burn mode, whatever that entails. If it's leaning towards rich, then you are going to using more fuel.

If I can go up a hill, keeping it in 5th, with below 70% throttle I can get better mileage, even if I might lose a little speed. If I can coast down a hill and pick up speed, while driving safely and reasonably for the conditions, then I can use that energy to help get me up the next hill, which will save me some fuel. How much, I don't know, yet, but some.

05-12-2008, 06:56 PM	#35 (permalink)
Whoops EcoModding Apprentice Join Date: Dec 2007 Location: Ventura, Ca Posts: 112 Whoop's Wheels - '89 Honda Civic Wagovan 90 day: 39.09 mpg (US) Thanks: 1 Thanked 9 Times in 7 Posts	You seem to have some presumptions and comments which I would like to make sure you are aware of, prior to my feedback on my experiences, in my car. When you are commenting, you seem to presume that you are in as high a gear as possible, going up hill, that you are able to maintain your speed and with a throttle opening which is less than 70-80%. Your question is further really restricted by the fact your car has a wide band oxygen sensor, but your question is about what seems to you to be conflicting information and which you have not been able to clearly discern an absolute answer to, for your car. Presuming my understanding of your presumptions is correct, I am offering this. I am driving a 89 Honda Wagon, 5 speed. At one time I had a voltmeter wired into my oxygen sensor, which is narrow band. What I found was that on my car it would stay in closed loop, monitoring the oxygen sensor, until about 80-85% throttle. At that point, it would go into open loop and the oxygen level would decrease substantially. If I can keep my speed up, keep the car in 5th gear and keep the throttle below 80% or so, then I use less fuel. However, if I have to drop down a gear or increase the throttle beyond closed loop, then my mileage goes down, drastically. Consequently, where you are looking for a hard and fast rule, their are probably not a lot. However, if you can keep it in leaner burn mode and you can keep your rpm down, you are going to get better mileage than if you can't. Whether you can, what speeds you can, whether you can keep it in 5th, how steep the hill is, how long the hill is are all subjective issues which are largely only relevant to you, your car, where you are driving and the conditions. I would focus more on trying to keep the your engine in more of it's lean burn mode, whatever that entails. If it's leaning towards rich, then you are going to using more fuel. If I can go up a hill, keeping it in 5th, with below 70% throttle I can get better mileage, even if I might lose a little speed. If I can coast down a hill and pick up speed, while driving safely and reasonably for the conditions, then I can use that energy to help get me up the next hill, which will save me some fuel. How much, I don't know, yet, but some.