--- MPG Gain With Engine off at Stoplights? ---

[basslover911]

I Am not talking about EOC, since i have an automatic, just turning off the engine at stop lights instead of leaving it idling...

Anyone has any mpg gains by doing this? ...I am trying to see if it really is worth it; If i gain only 1mpg I wount go through the trouble but if its something like 3-4mpg then of course...

[TKWPrime]

Depends a lot on your driving patterns and how much fuel you burn just sitting there at idle. The Blue BAT burns 0.6 gallons per hour stopped, idle, in gear. I can end up spending 15 minutes waiting at lights in a 20 mile urban drive. Let's say I get 20 mpg while in motion. I would burn 1.15 gallons with engine on at lights or 1 gallon with engine off. That is the difference between 20 mpg and 17.4 mpg.

[dcb]

Actually I just tested this. Idling at stops was %17 of my fuel in the test. Every car/driver/route will be different of course, so I added tracking of fuel spent at 0mph to the guino:
http://ecomodder.com/forum/showthrea...ting-5144.html

[tasdrouille]

In typical city driving, you use at least 10%-15% of your fuel idling. I read a research paper that quoted a city EPA figure of 17%, though the exact driving cycle was not specified (see zero inertia powertrain)

[saunders1313]

Turning the engine off at lights, especially ones you know are long is certainly worth it if you tend to do a lot of urban/city driving. You can EonC in an automatic, I do it all the time with my Monte Carlo. It helps if the gear shift is on the floor, but you can still do it if it's on the steering column. Simply shift into neutral (if the gear shift is on the floor you can go between neutral and drive without pushing the button. Coast up to the stop and with the brake applied just shift back into drive. You can usually shift into drive without the brake, but this depends on each individual vehicle.

[99metro]

I don't know about gaining, but I watch my "current" MPG drop off while I am idling. I suppose that any time you are not moving and not using gas, that would be an MPG gain, vice idling and not moving.

The rest of your question - I lose about 1/2 mpg max idling over 30 seconds - depending on how far I have traveled on that trip. The less time it has been since I started the trip the more MPG loss.

[PaleMelanesian]

On a typical drive in my town, I've measured about a 15% difference.

[aerohead]

Originally Posted by basslover911

I Am not talking about EOC, since i have an automatic, just turning off the engine at stop lights instead of leaving it idling...

Anyone has any mpg gains by doing this? ...I am trying to see if it really is worth it; If i gain only 1mpg I wount go through the trouble but if its something like 3-4mpg then of course...

July 1980 Popular Science,page 70:"Stop-go fuel saver",by Zemco Corp.,San Ramon,California.Tested on EPA Urban Cycle,the device(which does as you describe) improves mpg by 7.5%.

[ptsmith24]

Once I get my MPGuino calibrated, I'll test how much fuel I use idling and try to remember to post back.

[bhazard]

One thing I wonder about shutting the engine off is... does the computer go into open loop or does it run a little rich on startup? Or is that only on a cold start.