Driving Tips

[kickflipjr]

Its seems like there are tons of threads on ways to modify your car to save gas. We need some talk on driving. If anyone has tips (stop and go/ freeway driving/ hills) please share.

-I really have started looking way ahead for brake lights so i know when to let off the gas.

-For hills a try to build up speed before the hill and slowly
slow down (i try to time it to crest the hill).

-I ride down hills in nutral (unless it's really big then i leave it in gear so i don't die).


i put some more on another day.

[SVOboy]

Get on the saturn forums and ask about fuel injection when your foot isn't on the gas. I know with hondas if your foot isn't on the gas and rpms > 1100 you will inject no fuel, so if you're coasting down a huge hill or to a stop, in gear is good (this does not hold true for auto hondas).

[MetroMPG]

Originally Posted by SVOboy

I know with hondas if your foot isn't on the gas and rpms > 1100 you will inject no fuel, so if you're coasting down a huge hill or to a stop, in gear is good

my car purportedly has the same injectors-off feature (haven't independently confirmed it yet).

but even with that feature, decelerating "in gear is good" may not always be true.

you have to weigh the benefit of being able to coast further in neutral (while using a tiny amount of while fuel idling) against coasting in gear while using no fuel but experiencing greater deceleration from engine braking (meaning you won't coast as far).

which scenario is best depends on the circumstances:

example 1: going down a hill with a stop required shortly after it levels out? descending in gear is best, since you're using no fuel right up to the point that you're almost stopped.

example 2: coming off the freeway on a level exit ramp? coasting in neutral with the engine running could be more efficient. you go further on less fuel overall than when engine braking for a shorter distance using no fuel (since you either have to maintain highway speeds longer before letting off the gas, or you'll have to get on the gas after engine braking to drive to the end of the ramp).

i haven't done the math, but if you knew your car's specifics, you could figure out a formula of which is best when.

[chesspirate]

Originally Posted by SVOboy

Get on the saturn forums and ask about fuel injection when your foot isn't on the gas. I know with hondas if your foot isn't on the gas and rpms > 1100 you will inject no fuel, so if you're coasting down a huge hill or to a stop, in gear is good (this does not hold true for auto hondas).

I'm not the smartest guy when it comes to modern day fuel injection, so, with that in mind, i'm going to ask a very direct,simple question.
How does the engine survive without injecting fuel?

[SVOboy]

It's just an air pump. The wheels provide the force to spin it around, so it's not doing anything itself, that's why there is so much resistance coasting in gear, because the wheels are pumping the engine too.

[rh77]

Since I have a switch and wiring all set up, would it be beneficial to wire-in all of the fuel injectors to disconnect on decel (via the switch) and leave it in drive -- then like a manual, switch to neutral and leave the car off while rolling to a stop, or re-engage the Fuel Injectors for idle? I know the car uses fuel on decel, so theoretically it could work...

RH77

[MetroMPG]

i've been incorporating "pulse & glide" into my sub/urban driving, and it really seems to work. i am coasting in neutral much much more than i used to.

today i was out for a half hour or so, and managed to get 50 mpg in local driving. that's wild, considering 50 is my current hwy mpg average, and it's cold out. my avg in-town driving is currently 42.6 mpg (us).

this was in light sub-urban traffic, not stop & go. just stop signs, traffic lights & max speed of 60 km/h.

ironically, the scangauge is causing me to use even more fuel while i adapt this technique to my driving. i have to leave the engine running at all times, or the scangauge goes to sleep (and takes 20+ sec to wake up again, skewing the mpg calcs).

there are times i would switch off the motor and restart it with the clutch (e.g. descending a grade), but i have been leaving it on to see the MPG figures on the SG.

note - i haven't been doing pulse & glide to maintain a steady speed, just doing it where speed up/slow down is part of normal driving.

[rh77]

What I'd love to do (I know it's been discussed here) is to develop something that disconnects the fuel-injectors on throttle lift (0% throttle) and when the throttle is applied at all, the FI's re-engage. Problem is, I can do this with a switch hooked to the throttle linkage, but I'd also like to disable the system when the speed is less than 5-10 mph so I have power available after stopping (which would involve wiring a circuit into the speed sensor through the ABS or something -- which is beyond my expertise). Any wiring advice would help a load...

RH77

[SVOboy]

You could just wire it up with double switches, one that clicks on when the gas is off and another that click on when the vss read above 5mph, and wire them in series so it'll only work when both conditions are met.

[Flatland2D]

Does an automatic stay in gear if the engine gets shut off? You have to be able to overdrive the engine in order for this to work. Compare it to push starting, which you can't do on an automatic (at least as far as I know).

As for "pulse and glide" I'm coming to the end of my tank in which I've done that. So far it doesn't look like there was much improvement. Will post in appropriate thread when I calculate my results.