Quote:
Originally Posted by Old Mechanic
On hills of shallow grade I try to pulse uphill and coast downhill. In an auto tranny equipped car coast in neutral with the engine idling. In some cases when the grade is very slight, I'll pulse downhill to maintain a higher average speed. While coasting with the engine running is not as good as engine off, in most cars that coast will still yield mileage of over 100 MPG to as high as 400 MPG depending on your idle consumption amount and your coasting speed (example @ idle consumption .25 GPH, speed 60 MPH= 240 MPG).
My Sentra reengages without the toruqe converter locked up and I have done it without any issues at speeds as high as 70MPH. If your transmission does not like that type of reengagement then try rev matching with a little throttle "blip" when reengaging.
Pulse and glide is very effective when your average speed is lower that your torque converter lockup point, which in my Sentra is about 42 MPH. If your tranny really hates to reengage at the end of your glide then I would probably just not do it. It helps a lot if you have a tachometer which can tell you which gear the tranny is reengaging to. Typically it's a smooth operation and it was in the Toyotas I have owned (06 Corolla and 04 Scion XB).
It's always better to stay in lockup, but if your average speed is too low the P&G engine on. Never glide with the engine off in any auto transmission that requires the torque converter to be rotating for tranny lubrication. The potential for catastrophic transmission failure outweighs any possible benefit.
I accelerate very gradually, which cost very little in mileage, then coast in neutral and take advantage of the 100+ MPG coasting, particularly on downhills of almost any grade. If the grade is steep enough for your speed to increase significantly, then think backwards and reach the peak of the hill at a speed thatcresults in your speed at the bottom to not be so high as to risk a ticket. Of course all of this is done with respect for other vehicles which may react agressively to your driving with large speed variations. Adjust your technique to inconvenience others the least unitl their agressive driving becomes obnoxious and you feel compelled to let them know you do not appreciate it.
regards
Mech
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Thank you for your reply!
I have a relative who owns a 2008 Nissan Sentra CVT, so I can relate to your post.
So far the way I have been testing DWL is keeping the pedal pressure consistent and allow my speed to lessen up a rolling hill then allowing gravity to accelerate my car back up to speed. On the highway, it varies between 45-60 MPH on rolling hills and 55 MPH on flat sections.
Sometimes if I notice that after cresting a hill, I still continue to slow down so I adjust my throttle slightly until I gradually begin accelerating to my desired speed.
I have only had luck coasting in gear down hills with medium steep grades until my speed tapers off when I have to reapply acceleration.
I am leery of constantly shifting my automatic into Neutral for coasting in fear of wearing out the gear box and transmission parts so I have not tried it much.
This is all without an UltraGauge.
Am I doing this wrong?