I’m sure you have heard about us nut cases who practice “hyper-miling”, the art of driving with the car turned off as often as possible to reduce fuel consumption. My question is this, since I have a digital odometer, I have to keep my key “on” when coasting so I can accurately calculate my MPGs. Am I doing any damage to my electronics or electronic components by coasting with the ignition on like this?
What you are doing is flirting with disaster - no power assist to the brakes, no power steering and no power to the engine should you need it. Just stop doing it. You’re not saving money or the planet that way. Its just plain dangerous - and I think illegal. I’d kind of like to know where you live, what roads you use and when so that I can make sure not to be on them at the same time as you.
With todays computer-controlled fuel injection, the fuel flow is completely shut off when the car is decelerating and the throttle is closed. Turning off the ignition does NOTHING to improve mileage as long as the car is moving. If you are in the habit of coasting up to a traffic light with a “dead” engine, you will soon discover that your starter motor was not designed for that type of service and will fail very prematurely…
My question was more about the electronics involved in the process, not about what you think about the action itself. Thank you for your opinion though, I’ll keep it in mind.
I’m actually only doing it when I can coast upwards of 1/2 mile or more. It is doing something, my mileage improves considerably. My concern, as the question states, is how are the electronics affected, if at all. I understand the fuel cut off concept, but I can coast for a mile or more on many roads with the engine off, and the drag created when the engine is running reduces that considerably, so I am actually increasing mileage.
I’d be more worried about the loss of power steering and brake assist than whatever small fuel I saved. The “electronics” don’t care one way or the other.
Twotone
I must agree with Twotone…You are giving up too much to get very little…In an emergency, the sluggish steering and brakes would be a BIG handicap…
I don’t think that engine-off coasting is necessarily unsafe. Remember that plenty of cars have been sold without PS,PB at all–these cars aren’t considered “unsafe” for lack of these options. Assuming harvest has average-or-better strength for an adult, s/he ought to be able to safely maneuver a car w/o PS.
Also, the incremental risk associated with such ops are offset to some extent by driving at a slower average speed, as well as the increased situational awareness hypermiling requires.
OP, two things I would do:
- Delete the power steering: the real safety problem with engine-off coasting is that the amount of steering input required to corner varies–in an emergency situation, it won’t do to have to “stop and think” if one has PS or not!
Not only will this make steering effort a constant, but it’ll reduce parasitic loads, improving FE.
- Look into a “large capacity” brake reservoir: this will allow more stops with power assist. One could have enough reserve capacity so that one never (or at least very rarely) is without power brakes.
harvest wrote:
I’m actually only doing it when I can coast upwards of 1/2 mile
or more. It is doing something, my mileage improves considerably.
Normal coasting is when a vehicle consumes the least amount of fuel/mile (zero fuel on recent vintage cars). The type of coasting described by harvest (the OP) also represents a tiny fraction of mileage a car is typically driven.
Given the very small opportunity to save fuel (if any), and given the OP’s attitude in his replies, I can’t help but wonder if the placebo effect is occurring here.
This is just not the place to come and post about coasting and saving gas, too many regulars will “flame” you for the practice and pull from thier hip pocket how you are endangering freedom in the Western World by doing it, both ideas are rubbish, you wont save any gas and you are not going to cause a 15 car pileup by doing it either.One look at the Yahoo News each day and there is a story with the daily theme, “how you are doing something that will hurt you, keep you from getting a job, ruin your resume, cause a car accident” theme and it is carried over here.
Your base question, “will I harm my electronics”? the answer is no. Plenty of times the ignition gets left on for hours and hours in cars that mechanics were working on then suddenly decided they had something more important to do, and accidently left the key on, with the cars electronics suffering no ill effect. Now damage to the battery from being drawn totaly flat or from a 'rough" jump start that is a totaly different situation and one you have not asked.
don’t think that engine-off coasting is necessarily unsafe. Remember that plenty of cars have been sold without PS,PB at all
The cars that have been sold without PS and PB, are designed different and your would find that a car that came without PS will be much easier to drive than a car designed with PS when the PS is not functioning. Same with PB.
Transman can answer this better, but if your car is an automatic, shutting off the engine and coasting can be harmful to the transmission. The transmission fluid pump that lubricates the transmission is run off the engine. Other forum members can explain this better or correct me if I’m wrong.
I wouldn’t worry about the electronics, but start saving up for a transmission rebuild.
Ed B.
Only you can answer the odometer question. If you’re coasting a half mile put your odometer in the trip mode to see the tenths. As you coast in your manner… see if it counts up the distance or not.
You’ve never said the vehicle type here but I have a major concern about the transmission too.
Transman cound answere more specifically if we knew the vehicle type.
But generally, an automatic pumps fluid FROM the input TO the output. When coasting with the engine off, the input is not sending any fluid .
But with wheels rolling a portion of the internal parts are being spun form the output end.
Are they getting lubricated ?
Are they drying out sufficiently till you re-engage the engine ?
How much or how little of the parts are affected ?
This would be model specific if you wanted to know,
or we’ll just wait for you to tell how much your new transmission costs,
And therefore how much money was -saved- by shutting down your engine.
From personal experience, I’ve coasted a Ford Contour (2700# curb weight) and found it to be quite manageable >5 MPH. Granted, I’m a reasonably strong adult male with zero upper-body disability, but I “put the car through its paces” and found even extreme evasive maneuvers could be accomplished readily.
I stand by my statement that the “most unsafe” thing about engine-off coasting is that occasionally you have power steering, and occasionally you don’t. I’d still recommend PS delete if one wants to coast engine-off on a regular basis.
And yes, one can realize FE gains, most notably because the typical road gradient on “highway-class” roads matches up nicely with the gradient required to maintain 55-60
MPH indefinitely while coasting.
I tried something similar a few years ago with my 99 Civic just turning into my driveway. The steering wheel was harder to turn than the 65 Chevelle I had at the time(came with factory manual brakes and steering).
When you turn off the car, you can still brake once and if your hyper-miling you will have to start the car ignition to accelerate anyways. Part of hyper-miling is starting the car when you approach a corner to turn (so that you will have power steering) and when you need to accelerate or after braking. When hyper-driving you don’t tailgate or brake hard to decelerate (since the driver is coasting up to cars stuck at red lights), so don’t know why you would need power to the engine. An anti-theft device prevents my car from being able to start while in neutral (has to be in park), however I control my speed, coast up to turns, turn my car off at red lights, coast in neutral when i can, keep tires inflated and add +5 mpg (5*13g tank= 65 additional miles per tank)…and that’s without turning the car off! Also it’s not illegal, only to turn off the car when coasting down a mountain (not advised…you will brake once, roll-on and then no power brakes).
No placebo effect. People that hyper-drive can double the EPA miles per gallon rating on a car. I can’t fully hyper-drive, due to a anti-theft feature on my car, which prevents it from being able to start while in neutral (it has to be in park to start). However I control my speed, coast up to turns, turn my car off at red lights, coast in neutral when i can, keep tires inflated and added +5 mpg (5*13g tank= 65 additional miles per tank)…and that’s without turning the car off!
When you turn off your car thirty seconds at a time…even a minute. The transmission isn’t going to de-lubricate. And an oil pump sends oil to the engine not the transmission. You are right about the engine being off and the oil pump not working. However without the engine on there’s no need for the oil pump to lubricate the engine. Especially for 30 to 45 second intervals.
I don’t see a problem with the electronics being damaged by this practice, but my feeling is that any fuel savings will be negated by the energy used in manufacturing, distributing, and the sale of automotive parts such as starters, ignition switches, neutral switches, etc. that will wear out more often.
Factor in things like the fuel the tow truck burns when hauling a car in that has a prematurely gone south starter motor and it’s a wash in my opinion.
If one thinks that PS and PB doesn’t make much difference then try driving one of my vehicles with the engine off.
Take your pick; Lincoln, Merkur, SAAB Turbo, late 70s Camaro, or '60 Olds Super 88. They’re all a handful with no power assist, especially the Lincoln and the Camaro.
And the comment about the pump in an automatic transmission not functioning when the engine is off is correct. Some cars will tolerate this to a point; some will not.
If one thinks that PS and PB doesn’t make much difference then try driving one of my vehicles with the engine off.
Take your pick; Lincoln, Merkur, SAAB Turbo, late 70s Camaro, or '60 Olds Super 88. They’re all a handful with no power assist, especially the Lincoln and the Camaro.
I was operating on the assumption that the “hypermiler” in question likely drives a ludicrously small car. Obviously a bigger car has more issues, hence “not necessarialy unsafe…”