How to over-ride computer RPM while coasting?

[ksa8907]

Originally Posted by johnlvs2run

I'm interested in your tests of coasting at 1 rpm, and how they support your theory that coasting rpm makes no significant difference to mileage. Likewise, please post some evidence that 3000 rpm, for example, is no worse for mileage then 1500 rpm, and whether this applies to gas use when idling at a stop, as well as when coasting.

Fuel consumption is more dependent on engine load than engine speed, particularly when engine speeds are well below the normal torque curve. The question directly related to the OP and his/her situation: Is the additional fuel usage from the elevated idle enough to actually be concerned with? We don't know until it is measured.

[mcrews]

Originally Posted by johnlvs2run

I'm interested in your tests of coasting at 1 rpm, and how they support your theory that coasting rpm makes no significant difference to mileage. Likewise, please post some evidence that 3000 rpm, for example, is no worse for mileage then 1500 rpm, and whether this applies to gas use when idling at a stop, as well as when coasting.

read this.....again
it's easy to get fixated on something like this....had a tarsus that did the same thing.
But there are probably three other things you could do to get better mileage.half of a quarter of a gallon OVER 1 hour is nothing.
maybe you can reduce the rpm in half, but it doesn't use twice as much gas to run 1500rpm (IN NEUTRAL). And honestly, how much time do you really spend coasting....
__________________________________________________ ____
1.) buy a scangauge
2.) aba test your theory
3.) report back

you can discuss all the 'theories' you want until you are blue in the face.

everything in life is a bell curve. It's not worth dealing w the fringe stuff UNTIL you address the stuff in the middle.
SO....... how much time and distance is spent 'coasting'? (the fringe stuff) Which by the way has the LOWEST consumption of fuel on the whole trip probably only 10-15% of driving consumption.
FOCUS on the stuff that matters.

[j12piprius]

I'd like to see some evidence of 1 rpm vs 3000 rpm not making any difference to mileage when coasting in neutral, and the same when idling at a stop.

In my experience that is not true at all.

Plus if fuel use while coasting made no difference to mileage, then no one would use bump starting and engine off coasting.

[mcrews]

Originally Posted by johnlvs2run

I'd like to see some evidence of 1 rpm vs 3000 rpm not making any difference to mileage when coasting in neutral, and the same when idling at a stop.

In my experience that is not true at all.

Plus if fuel use while coasting made no difference to mileage, then no one would use bump starting and engine off coasting.

it's easy to get fixated on something like this....

[mcrews]

your question was already answered by another poster. you chose to ignore it. you keep repeating the same question.
AGAIN, in 2012 when the op's car was manufactured, Toyota (AND MOST OTHER BUILDERS) really were trying everything they could to get better mileage. So I would bet that the rpms being higher is for a pretty good reason. AND that changing it will have greater negative result than positive results.

Here chase this rabbit down a hole....learn to get out of your car VERY FAST so the air conditioning doesn't escape........and waste fuel.
Pay attention!!!!
FOCUS!

You spend a VERY little amount of time coasting. PERIOD.
Focus on what makes a difference.

[mcrews]

and finally I didn't say "it didn't make any difference"....pay attention!
I said that there was not a simple "if this drops 50% than that drops 50%' relationship.

Which was answered....which you ignored.

[j12piprius]

Originally Posted by mcrews

it's easy to get fixated on something like this....

Yeah I can see that, the bold caps, exaggeration, ignoring facts etc.

Meanwhile, no evidence. When you get that 1 rpm test completed let me know.

Personally I spend the majority of time coasting, instead of having my foot on the gas.

[3-Wheeler]

Maybe this will help....

I drive a Honda Insight, and for the past few months the HV battery is starting to get finicky, so I don't trickle charge it much.

When the HV battery voltage gets low, the ICE engine idle goes from a normal 1000 rpm, to about 1200 rpm or so.

The effect on gas consumption at idle?

FCU display stays maxed out at 150 mpg until I reach a coast down speed of 20 mph when idling at 1000 rpm.

FCU display stays maxed out at 150 mpg until 22 mpg when idling at 1200 rpm.

That's a difference of 10% in fuel consumption at idle.

The consumption at load is much higher than this, so the result of idling at 1200 rpm is pretty small in the grand scheme of things.

Jim.

[mmonce]

So I have an update. I started using the DashCommand iPhone app so I get some data.
I have been looking at the gph while in neutral and while coasting downhill in 6th gear. The RPM's and gph remain the same weather in neutral or coasting downhill in 6th gear. Approx 1,100 rpm = .9gph (this is at 45 mph). So there is no savings in gph between coasting in gear or shifting to neutral.

My base idle at 600 rpm is .3 gph. So my ECU is nearly doubling my rpm and tripling my gph while I coast downhill at 45 mph (no foot on throttle). Tripling my gph is significant when it is not necessary. Older cars used to get better mpg than autos. Now the opposite is true. Part of the new inefficiency is our car's ECU not allowing our engines idle when we are coasting in neutral or gear.

What I did not know is if someone was able to link their laptop to a Toyota ECU and make a simple mod to reprogram this high idle. A friend of mine does some high end car tunes. He says Toyota's ECU's are really locked down for mods.

[oldtamiyaphile]

Originally Posted by mmonce

Older cars used to get better mpg than autos. Now the opposite is true. Part of the new inefficiency is our car's ECU not allowing our engines idle when we are coasting in neutral or gear.

EPA doesn't test coasting in neutral, so that's not why autos sometimes do better on the EPA cycle.

Real world, manuals still beat autos.

Besides, you need to be at 2000rpm before gliding in gear to enter DFCO and use zero fuel. This isn't very useful in an FJ but works brilliantly in small cars. You can also key off with the car in gear, this keeps everything working but essentially means forced DFCO.