View Single Post
Old 09-30-2009, 09:28 PM   #56 (permalink)
cfg83
Pokémoderator
 
cfg83's Avatar
 
Join Date: Dec 2007
Location: Southern California
Posts: 5,864

1999 Saturn SW2 - '99 Saturn SW2 Wagon
Team Saturn
90 day: 40.49 mpg (US)
Thanks: 439
Thanked 532 Times in 358 Posts
Jammer -

Quote:
Originally Posted by Jammer View Post
Thanks again. I mean no offense, after all your the mechanic, but I can not see where downshifting down a mountain with the engine running results in NO fuel being burned. After all I think the DFCO cut off is around 2,500 RPMs, so I have to assume gasoline is burning to that point. I guess I am curious if it is possible to go EOC down hill by gearing down to slow down with the key in the off position, or will this idea end up burning gas some how? My mind is real fuzzy on this one.

Also there seems to be a limit to braking during EOC in my Cobalt XFE, or is that my imagination? As far as I can tell if I am going a long distance in EOC my brakes work fine for a few pumps then do not work until I start the motor back- which can be extremely dangerous around these curves here. I am still learning how to do all of this safely, but I no longer have the fear I did back when I first tried it and had trouble.

I do plan on getting some home insulation and taping it around the battery in the trunk and see if that helps my battery to charge/keep a charge or not.

My best.
I just started doing this on a steep hill I have when I leave for work. If I keep it in 3rd gear and actually accelerate such that I am at about 2800 RPM, I get the DFCO without using EOC. I know this because I have a digital A/F ratio guage, so I see it go lean. The benefit is that as long as the RPMs are above 2500 RPM, I have full brakes and full steering all the way down the hill and I have less need to use my brakes because I have engine braking in my favor, just like a semi. I do use a little fuel to get above 2800 RPM, but I am 100% safe doing it. I learned this recently, so now I can't wait for a great big hill on the grapevine to test it on.

My rule of thumb is that I have one lonngggg power assisted brake. I say this because I gleaned (incorrectly?) on this forum that the vacuum reservoir doesn't dissipate as long as I keep my foot in the brake. I also don't try EOC in curves because I need my (mechanical belt-driven) power steering.

CarloSW2
__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote