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-   -   A case against pulse and glide (https://www.fuelly.com/forums/f33/a-case-against-pulse-and-glide-6270.html)

GeekGuyAndy 10-02-2007 03:00 PM

A case against pulse and glide
 
I drive the same vehicle on the same trip for 5 round trips a day now as a shuttle service for my college. Up until last week, the best FE I could get was 26.5mpg, and I could do it consistantly. I tried EOC a few times and was able to get 29.5mpg, which seemed resonable also.

But then I stopped doing pulse and glide and tried driving with a constant throttle, at 10% most of the time, and 15-20% on hills when needed at 3 points. With that, I was able to get 28.5mpg regularly, and 32.5 with EOC.

So that means that without using P&G I gained 7-10% gas mileage! I'm going to try out several different throttle percents over the next week and see what works the best, but I don't think that I will be using pulse and glide like I used to anymore.

I thought P&G was supposed to be more efficient since the engine is running at a more ideal speed, but apparently that's not the case. Does anyone have ideas? Can anyone with a SGII try this and tell me their results?

omgwtfbyobbq 10-02-2007 03:07 PM

I'ma guess automatic trans. area not good for P&G, and not enough throttle on the pulse.

skewbe 10-02-2007 03:28 PM

Confirmed. Best I could do around town with the auto saturn was like 40 w/p&g, when I put the stick shift in there I could get 60 no prob.

This really is a case against automatic transmissions if you ask me.

GeekGuyAndy 10-02-2007 03:44 PM

It's a Chevy Venture van, automatic, 3.4L.

I'm just surprised how much I read about P&G but no one talks about just constant driving. I guess automatics are the minority here though

2TonJellyBean 10-02-2007 03:46 PM

Phew... I had found the same thing. Once into top gear and especially when the TC locks up, DWL has been better for me than P&G. I was just blaming my poor P&G technique.

skewbe 10-02-2007 04:08 PM

Not in the minority certainly in the US, only 10% of cars sold were manual transmissions in 1998, and a lot of those were sports cars. We haven't been real serious about MPG here in the US.

cfg83 10-02-2007 04:09 PM

2TonJellyBean -

Quote:

Originally Posted by 2TonJellyBean (Post 74890)
Phew... I had found the same thing. Once into top gear and especially when the TC locks up, DWL has been better for me than P&G. I was just blaming my poor P&G technique.

We should be more clear on that. Maybe this distinction needs to go into the FAQ/driving tips section.

EDIT : i.e. the distinction that P&G may not be appropriate for automatics.

CarloSW2

bowtieguy 10-02-2007 04:27 PM

i too have an auto V6(3.8). not convinced of pulse and glide, but i do just glide on the last mile home, getting of toll roads,etc.
preliminary results good so far.

northboundtrain 10-02-2007 04:39 PM

I think there are significant inefficiencies in accelerating with an auto. The torque converter does not transmit energy as effectively as a clutch. As 2Ton said, keeping the TC locked up is probably best for an auto.

rh77 10-02-2007 05:22 PM

Don't P&G often
 
I don't really P&G often with either auto car in the Garage. Most of the time, my P&G involves EO-coasting down a hill at highway speeds, slowing due to drag, and starting back up at about 5 mph under the speed limit.

DWL on hills can be argued as a form of P&G, I suppose...

RH77


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