Hang Time: Exploiting ECU Fuel Maps for Fuel Efficiency

[Amdkt7]

Originally Posted by Sparcoboy

I've tried this but for me it wasn't worth the effort. Doing the same trip every day, I had to fuel up sooner with this technique. The problem is, I think, that in order to accelerate back to your higher speed you burn more fuel than you saved by lifting the accelerator a bit. As long as you're decelerating you burn less fuel, meaning more mpg but the time you accelerate you get only half the mpg's than before. For me driving at a constant speed has proven the best.

Because of pumping losses the pulse and glide technique works. Hangtime is the same thing as pulse and glide. Some use extreme variations of pulse and glide, and it is tricky to know just how much gas to give it during pulse.

The reason it works is due to pumping losses (due to nearly closed throttle). The engine loses energy trying to suck air past the closed throttle). I'm not sure if hang time really works as the fuel does not get shut off like pulse and glide, but I see the same thing on my ecometer. If I time my glides according to the slope of the road I can really get a big boost in FE. During pulse the throttle is open wider, reducing pumping losses, and the engine operates more efficiently.

I'll experiment with hang time some more. I was noticing the same thing, but have not tried to exploit it.