Has anyone ever tried to maintain DFCO with a 5-speed, example, Coast in 5th gear watch the rpms wait till it hits about 1,000rpm then downshift to 4th.. 3rd...2nd. Or will this approach not work because of the clutch, (when you push in the clutch the rpms go below 1,000). Any advise would be great
I always lose DFCO when the clutch goes down for the gear change.
If you do it at higher RPM so there's time for the change before the RPM drops too far, the ECU may interpret that as a downshift for acceleration, having been programmed for such a sudden and violent downshift to mean you're about to ask for performance...you know, come to think of it, I don't remember testing that particular strategy with the fuel rate meter.
vxdude, that is exactly what I do in my VX, with one exception. When the accessory loads are added the DFCO threshold rises to about 1200 RPM. Then you need to downshift at slightly higher RPM.
I even cycle the AC when its real hot and I know I can not slow down fast enough with DFCO alone.
Timing your DFCO can save a lot of fuel if you can minimize idling, and roll through the intersection without stopping completely.
I have used DFCO to slow down at 70 MPH when drafting downhill and overtaking the host vehicle, as well as to slow down on steep grades where my speed is higher than I want.
Downshifting at RPM lower than 1500 is not that hard on your tranny.
Every time you let off the gas, even when upshifting you have some DFCO.
I usually upshift at 1800 to 2200 RPM. I try to avoid any engine operation above 2500 as well as any throttle imput above 20%.
Most of my driving is local, and I use the cheapest 10% methanol fuel I can buy. Last tank was 55 MPG and the fillup was $2.729 per gallon.
In some cases when I DFCO and need to accelerate I actually go from 5th to 4th or 3rd, when I need to accelerate at a faster rate to not tie up traffic. The light timing here requires you to actually go at least the speed limit, or you get into catching every light too late, and having to slam on the brakes and loose all of your inertia.
I P&G at speeds below 50 MPH, but from there on up I just stay in 5th gear. 5th gear is good down to 30 MPH in my car even with the AC running (which I only use when temps are above 90 degrees here).