Quote:
Originally Posted by nj1266
You do not have to turn the engine off during the glide period after the pulse. All you have to do is keep the car in gear and lift off the gas. The injectors will shut off and engine will become an air pump. I have a wideband installed on my car and when I glide in gear with my foot off the gas and the engine on, the wideband reads 20.xx AFR. That means you are getting 20.xx parts of air to one part of fuel. That is way better than gliding when the car is out of gear and the engine is on becuase the AFR is 14.7:1 under these conditions. 20.xx:1 is far far better than 14.7:1 and that saves you more fuel. Ofcourse, shutting the engine off is best of all, but it is also dangerous as hell.
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I disagree.
Shutting off the engine isn't dangerous if done correctly. If you wait until the engine is hot, and use a fuel cut switch, there's very little risk of damage to the engine or other components. The loss of power brakes is very predictable, and if you don't press and release the brakes much, you retain assist. As for power steering, well, you don't need that anyway, but some cars have electric power steering or even manual steering.
The technique you describe is "pulse-and-DFCO", which underperforms pulse-and-glide. Spinning the engine during DFCO takes energy, and you slow down much faster than you would in neutral. Because P&G allows much longer glides, it's more practical so you can use it more often, and your car uses less energy per mile for more mpg.
BTW, your AFR should approach infinity, as you've got clean atmospheric air being pumped through the engine, and almost no combustion products mixed with it.