How To maintain brakes while engine off coasting

[ecomodded]

Originally Posted by ksa8907

what he said, and to elaborate, engine controllers will read the crank sensor for timing up to around 2500rpm then switch to the cam sensor above that, because it runs at half the engine speed.

That is a good piece of information. For my TDI, highway rpm is less than 2200 rpm

[UFO]

I doubt there is much benefit on steeper hills (engine braking), as fuel is cut anyway, but obviously coasting out of gear saves 0.8-0.9 gallons/hour, idle consumption.

Looking forward to results.

[ecomodded]

The kill switch is more effective at saving gas then engine on braking on the steep hills, as follows.
It will be best to use neutral when ever the full power brakes and steering is not needed. The steep grade hills will be approached engine off and coasted for the first few 100 meters until the speed increases then put in gear, at the bottom of the hill it will be put back in neutral,still engine off and coasted until i need to restart the car.
Simply put there is nothing more fuel efficient then a non running motor.

The idle consumption is more then i anticipated, .8 or .9 of a gallon a hour is large. I should be seeing a hefty mpg gain. With a modest 10% mpg improvement it would mean 6 mpg with my car.

[Piwoslaw]

Originally Posted by ksa8907

what he said, and to elaborate, engine controllers will read the crank sensor for timing up to around 2500rpm then switch to the cam sensor above that, because it runs at half the engine speed.

This shouldn't be a problem for us hypermilers since we hardly ever rev that high, plus the engine will get killed after returning to idle at the soonest, to allow the turbo to cool off somewhat.

Ecomodded, someone here once remarked that kill switches should be of the momentary type, since it is possible to push and forget, especially if something suddenly grabs your attention. I believe there was something about a situation when he needed to bump start fast, but forgot to flip the switch and the engine wouldn't start. Lots of panic but no serious consequences, thankfully.
Just something to keep in mind.

Originally Posted by ecomodded

The idle consumption is more then i anticipated, .8 or .9 of a gallon a hour is large. I should be seeing a hefty mpg gain. With a modest 10% mpg improvement it would mean 6 mpg with my car.

That is high. My 1.6 turbodiesel consumes ~0.52 liters per hour (~0.14 GPH) when warmed up. Even with A/C on it's between 0.8-1.1 LPH (0.21-0.29 GPH).

BTW, is your PS pump electric, or is it run off of the engine?

[UFO]

Originally Posted by ecomodded

The idle consumption is more then i anticipated, .8 or .9 of a gallon a hour is large. I should be seeing a hefty mpg gain. With a modest 10% mpg improvement it would mean 6 mpg with my car.

I have a decimal point off. I think the idle consumption is more like 0.08 - 0.09 gallons per hour.

I'm sort of anxious to ruin my automatic, I want to convert mine to see what I could do with a manual.

[ecomodded]

I was originally one of the people thinking the momentary switch would be the best way to go, because of safety.
Then (see 1st post) i realized that i could have brakes and power steering if i used the on/off rocker type switch.

I would not be able to engine off coast in gear if it was the momentary type of switch, the car would just start up.
I put the rocker switch in because i wanted to EOC with brakes, my safety concerns were met plus some, as i also have power steering. Beats a momentary switch, for my purposes.

[ecomodded]

Originally Posted by UFO

I have a decimal point off. I think the idle consumption is more like 0.08 - 0.09 gallons per hour.

I'm sort of anxious to ruin my automatic, I want to convert mine to see what I could do with a manual.

a) if you find it, please re post, you may of been right the first time.

b)If you replaced it,you could sell the auto !

[ecomodded]

Quote Piwoslaw:

That is high. My 1.6 turbodiesel consumes ~0.52 liters per hour (~0.14 GPH) when warmed up. Even with A/C on it's between 0.8-1.1 LPH (0.21-0.29 GPH).

Aha ! this also clarifies UFO's first numbers as incorrect, they may of been .8 or .9 Lph ? rather then gph a posted.

[UFO]

My Scangauge is set to 1.9 liters, dieselA and -21% fuel. This gives me accurate mileage estimations for my daily commute, but I suspect it is significantly off on idle fuel consumption. It shows 0.09 gph when warm at idle.

However, I don't know what it really is because I went on a 360 mile road trip through the mountains last weekend, and with all the coasting and engine braking, as well as all the hill climbing, my scangauge mileage was 65 mpg at the end of the trip. Actual tank mileage: 50mpg.

[ecomodded]

My car uses about 1 gal. per hour while driving, so the less time the motor is running the better. I do a lot of engine on coasting now so my gains will not be as much as someone else, who doesn't coast around constantly to begin with.

The switch is going to take some time before it becomes routine,in two weeks i should be adept at it..
I have to flip the switch off then reset the ignition to have it ready for the next start , move the key down one position then back up.
I find it bothersome all the same but i will get used to it shortly as with all new things.

I have to comment on the quietness and the great feeling you get coasting engine off/ in gear with power steering and brakes, the motor becomes powered by the wheels the wheels by the hills or momentum, its reversed, its perfect.