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Old 11-28-2023, 07:20 PM   #1 (permalink)
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Question Coasting in Neutral vs in Gear DFCO vs no DFCO?

So the generally agreed upon coasting hierarchy is E-Off Neutral, E-On Neutral, E-On Gear, Brakes.

Was wondering where would coasting in gear without DFCO would fall, and if anyone else has experimented with this. I'm uncomfortable with shifting in and out of Neutral too often, so I've been trying out adding just enough throttle to prevent DFCO from activating, and get close to idle's fuel rate. I noticed that the ignition timing readout correlates pretty well with when the engine nearing DFCO (48+), and I combine it with the A/F data (18+ = no fuel) to be sure I didn't back off too far.

I have had the opportunity to test it out on a couple of longer drives, the engine is spinning at a higher RPM than neutral so slightly more internal friction to fight, but I can let the RPM steadily drop so the throttle can be restricted a bit more than idle?

I don't really have a way of testing the travel distance difference between neutral and in gear with fuel, but it's definitely less braking force than DFCO.

Weirdly I can feel the steering wheel vibrate a bit at very low throttle openings. FF drive, so whatever the engine is feeling is bouncing through to the steering column, not sure why. Lugging is too low RPM, right?

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