Tested: The Most Efficient Way To Accelerate With An Automatic (Toyota Matrix)

[mechman600]

Originally Posted by E.Roy

Could you also place a resistor inline in the voltage signal wire to the ECU, would that reduce voltage?

Nope.
A resistor inline with the signal wire will not reduce voltage, at least not reliably. However, a resistor between the signal wire and sensor common (ground) will by pulling the voltage towards ground. The best way to manipulate the signal voltage is to do this with a variable resistor so it can be fine tuned.

[BLSTIC]

No, the circuit for the throttle position sensor doesn't work like that. The internal resistance of the computer and sensor is too high (and so current flow is too low) for a dropping resistor to function correctly. The part you are looking for is called a potentiometer (pot). The pot is a voltage divider, and they effectively split the voltage evenly between two sources and output that voltage on a third.

So cut the TPS output. Wire the TPS side of this wire to one end of the pot and *sensor* ground to the other (both wires are present at the sensor). Wire the ecu side of the cut wire to the wiper arm terminal (typically the middle one on knob-style pots).

You now have "standard TPS signal" at one extreme of adjustment and "computer sees the TPS as always closed" on the other. However that can effect open loop running (necessary for engine and cat converter health at high loads) and other things like a/c cut-out at high loads. But it will affect the kickdown on a fully computerised gearbox

[Joggernot]

Originally Posted by Old Mechanic

Now the bike is a different game for me. It's fun to just get it on down the road and I can do that on the bikes and still beat 60 MPG. I confess I was trying some coasting on the 94GS today, it might get me another 10% if I can maintain the effort, but I don't like to create distractions when riding on two wheels. It's kind of a passive agressive technique which maintains best separation from the inattentive and imbecilic, especially now that deer season is here.

regards
Mech

I use coasting in the foothills of TX to improve mileage on my bike. There are some hills with a 2 miles coasting distance, if done right. Always engine on, not off.

Joggernot

[sbestca]

Trusting the scangauge or onboard readout can be a bit tricky in these situations, just as trusting a vacuum gauge was in the old days. My on-board display tells me that brisk acceleration to speed gives the best accumulated average fuel economy. Brisk acceleration in this case is 1/4 to 1/2 throttle. Feathering it at less than 1/4 throttle and a slow ramp to speed holds a low economy for longer time period. I don't know if I trust this total for the reasons others have given about how the economy data is generated.

Experimenting with driving style in tank to tank results seems to back up that the brisk acceleration returns the better tank averages over extremely slow acceleration.

The original poster's comments about lock-up speeds and loads are very astute too.
I find I have to accelerate to the shift point speeds dictated by the transmission.
Then I can back off and coast or lock the cruise on to keep over downshift speed.

Very interesting. Steve

[rajadaja]

Has anyone tested different acceleration rates on hilly terrain? I live in an area with rolling hills and I try to minimize my acceleration while on inclines and accelerate harder on the tops and downsides on any hills. Hitting peak speeds (even above speed limit) in the valleys and allowing the car to slow a bit as I climb the hill - this seems to give me better mileage than cruise control

[Daox]

I typically accelerate up a hill (or maintain speed), and coast down. This maintains a more steady speed and IMO is probably less annoying to other drivers.

[christofoo]

(Doax beat me.)

Originally Posted by rajadaja

Has anyone tested different acceleration rates on hilly terrain? I live in an area with rolling hills and I try to minimize my acceleration while on inclines and accelerate harder on the tops and downsides on any hills. Hitting peak speeds (even above speed limit) in the valleys and allowing the car to slow a bit as I climb the hill - this seems to give me better mileage than cruise control

P&G(/EOC) is the best way to treat hilly terrain. The gains are on the downhill. The only point of DWL, for example, is to avert downshifting in an auto. The end-game should always be minimizing total number of revolutions (barring WOT, lugging and braking).

If you never get into neutral it tends to be a wash (barring WOT, lugging and braking).

Conventional tranny Otto-cycle vehicles have only 2 efficient modes: brisk-acceleration (or up-hill) and neutral (EOC incrementally better than Glide [engine-on]).

[sbestca]

Originally Posted by christofoo

(Doax beat me.)

P&G(/EOC) is the best way to treat hilly terrain. The gains are on the downhill. The only point of DWL, for example, is to avert downshifting in an auto. The end-game should always be minimizing total number of revolutions (barring WOT, lugging and braking).

If you never get into neutral it tends to be a wash (barring WOT, lugging and braking).

Conventional tranny Otto-cycle vehicles have only 2 efficient modes: brisk-acceleration (or up-hill) and neutral (EOC incrementally better than Glide [engine-on]).

I would agree with this. My 2012 Grand Caravan will glide in gear with little engine holdback and will shut off all fuel so the downhills really make up the fuel lost on the climb IF you stay off the pedal. Whereas coasting down in neutral shows 2.5 L/100kms and maintaining load shows the same 5-9 L/100kms it would get on a level. On the climb I use enough gaspedal to hit my maximum speed at the bottom and just hold enough throttle to keep it above the 60kph downshift speed at the top. I may accelerate slightly over the crest if there is not enough slope to do so on the other side, otherwise I let the slope do the work in gear with my foot off the gas.

Other auto transmissions did not work quite the same. 2000 Jeep Cherokee would downshift at about 75kph on a hill climb, really wrecking fuel mileage so I had to keep it above that speed. 97 Taurus still fuelled the engine with foot off gas and had lots of hold back so I used neutral a lot.

Using these techniques (that you guys have been teaching me!) I have seen tanks of 5.8-6.5 L/100kms in my Dodge Caravan over 400-1000kms. My Cherokee showed me tanks of better than 10L/100kms and the Taurus actually broke 7.8L/100kms when values of 9/15/11 are more common for these vehicles. Grand Caravan is regularly showing me 750-800 kms per tank and as much as 1100 on flat highway trips when it used to be as low as 400kms (and still is in winter and city driving).