Originally Posted by
sugarwaterpurpl damn i get around 400 on 10 gallons hahaha. Baws! And i didnt know that about rolling in neutral. The injectors stop?
Other way around, rolling in neutral = using gas. Going down hill in gear = usually means no gas used.
One time I was low on gas and still had a ton of hills to go through in West Virginia on 64. Well I decided to coast on as many as it was safely to do so. I get to the gas station, my mpg is similar to what it was usually, actually I think it was 1mpg less. That's when I thought coasting in neutral was good for gas.
Originally Posted by
WingmanSR20
Here's what I never got. If you are sitting in your driveway holding at 3K rpm, and take your foot off the gas, the car idles. Air is cut down to idle air, the MAF reacts to that, injectors supply idle amout of gas to match idle air for an idle mixture, and the engine revs down until it reaches idle RPM. So if you do the same while driving, whether in gear or not, why would it be any different?
The injectors are supplying enough fuel for idle as the air supply with your foot off the gas is for idle. It doesn't care how fast you're going, doesn't care if your clutch is in or not, it's just going to supply gas to match the incoming air. It simply engine brakes until you get to idle RPM since that's all the power it's making at that throttle location.
The only true way to conserve is to turn off the ignition when coming to a stop. Nobody's going to do that.
Using no fuel is always going to be better then using fuel, for MPG's. Something to keep in mind while idling you are getting 0 mpg, since your not moving. This is why a lot of new cars turn off on stop lights and then start back up when you depress the clutch.
If you use a wideband, while going down hill in proper gear, (small hills generally are fine up to 3rd gear, if you go to say 5th gear on a small hill, your not rolling fast enough to keep the engine running properly thus you will need gas to keep engine running), anyway while in proper gear going downhill you will see your afr's go to the way lean, mine reads 23afr (because gauge itself doesn't read any leaner), but when datalogging it shows afr's above 50. That's no gas being used. If you have a ScanGauge 2, you can see your MPG's go from 20-30 to 100-200mpg easily.
Originally Posted by
WingmanSR20 Nope, never had a reason to do a wideband. What criteria would a regular car use to decide when to cut injectors though?
Mainly when decelerating and when going on a hill that's steep enough to keep you rolling without needing fuel support.