DWL/Pulse and Glide/Torque Lockup in an Automatic vehicle

[SilverCrown9701]

Hello,

I noticed recently from reading this forum that driving with load is more beneficial to automatics versus using cruise control in areas with rolling hills.

I'm curious as to actually how one drives with load to increase mileage...?
I drive 55 MPH on the highway as well...but I am really struggling to receive better fuel economy in 20-40 MPH zones in town.


DWL...

1.) Do you keep a constant pressure on the accelerator, allowing my speed to drop down to 45-50 MPH and then allow gravity to increase my speed up to 60 MPH keeping the same throttle pressure?...

OR...

2.) Do you keep a constant pressure on the accelerator on the way up the rolling hill, allowing my speed to drop down to 45-50 MPH and then take my foot off the accelerator and coast in gear with DFCO??...


Pulse and Glide...

1.) How do you pulse and glide in an automatic without damaging your transmission in city and highway driving??...


Torque Converter Lockup...

1.) Is it better to keep the transmission within the torque converter lockup range while performing EITHER technique or is it ok to allow my speed and gears to fall below this top gear/OD range??...

[user removed]

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

[SilverCrown9701]

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

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?

[user removed]

I don't see anything wrong with your current technique and considering the cost of a transmission repair, if you are not comfortable with coasting in neutral then don't do it.

I have been doing it for a long time with no problems, but then I could probably get mine repaired fairly cheap.

regards
Mech

[SilverCrown9701]

Originally Posted by Old Mechanic

I don't see anything wrong with your current technique and considering the cost of a transmission repair, if you are not comfortable with coasting in neutral then don't do it.

I have been doing it for a long time with no problems, but then I could probably get mine repaired fairly cheap.

regards
Mech

Awesome!

So far I'm at 413 miles and my gas needle is halfway empty. If I used cruise control, it would be around the 285-300 mile mark on the odometer. It has an 18.5 gallon tank.

[XYZ]

Originally Posted by Old Mechanic

I don't see anything wrong with your current technique and considering the cost of a transmission repair, if you are not comfortable with coasting in neutral then don't do it.

I have been doing it for a long time with no problems, but then I could probably get mine repaired fairly cheap.

regards
Mech

Nothing beats hearing an honest response here.

I'll add what I know: You can coast in neutral in virtually any car that has an automatic transmission. Any detriment to the transmission will only occur when shifting back into drive. However if you coast to a stop or a near stop (10 MPH or less) before shifting back into Drive, it won't harm your transmission. As far as I know this works with all automatics, no matter how old the vehicle is.

[SilverCrown9701]

I DID IT!

I drove 504 miles this past trip cycle in mixed traffic and averaged 37.4 MPG!!!

This is the most I've ever earned and I'm very proud of myself!

Excuse my excitement, I'll calm down lol. I just can't believe how well I did in such a big car as the Camry. WOOHOO! My biggest changes were implementing DWL and not using air conditioning. I've listed my fuel up in my garage along with what I did differently from my last trip cycle.

My new goal is to reach 40 MPG average

[Daox]

Woohoo, congrats!

[mcrews]

cant imagine the a/c would cost too much w a big V8

edited: cant imagine I confused this with the crown vic poster.....

edited#2: his screen name is "CROWN".....Come on....give me a vowel!!!!!

[Daox]

Hes running a 4 cylinder Camry.