Time spent at traffic lights - Engine OFF

[Clev]

Originally Posted by MetroMPG

I understand Wayne wore out the starter in his Accord, but the number of starts on his will vastly outnumber the typical ecodriver.

A new starter for my Accord costs about $120. I've saved about $850 in fuel so far over what I would have spent getting EPA mileage. I'll risk it. :-)

[cfg83]

jkp1187 -

Originally Posted by jkp1187

Well, I've had to replace starters on several of my cars - 1988 Chevy Celebrity, 1995 Chevy Beretta, 2000 Chevy Impala. Granted, all of them were beyond 100,000 miles at the time of the replacement, but I take it more or less for granted that I'm going to have to replace a starter at least once.

Note that the above replacements were made before I made it a point to turn the engine off at long lights.

For what it's worth, BMW's owners manuals claim that four seconds of idling is the break-even point for idling versus shutting off. Of course, shutting down and starting up for every 4-second delay sounds like you're asking for trouble. My rule is that I'll shut down if I know the wait will be more than 20 seconds AND if the oil is at operating temperature.

I haven't replaced my starter yet (knock on virtual wood), but at 182K miles, it's gonna happen sooner or later.

I believe the 4 second idling number. In colder climates, one caveat to this is unheated oxygen sensors (aka oxygen sensors that only start to work when exhaust gases heat them up to "temperature X"). Heated oxygen sensors are heated using electricity from the battery, so they stay heated as long as the car's key is in the on-position. At extended stops in cold weather, an unheated oxygen sensor could cool off to the point where it is no longer operating normally. The ECU/PCM can detect this state and will spend more time in open-loop mode, which would burn more fuel.

I also wait for the engine to warm up before employing engine off. I won't using engine-off unless I already know the timing of the light. 20 seconds sounds about right for me too.

CarloSW2

[drewwitlin@hotmail.com]

I wish that I could EOC to traffic lights, but being an Auto and not on the list, I would damage the Torque converter.

I had read on another post that someone with at 1.5L had figured out the recoup of shutdown was 11secs. It would be great if it was only 4 secs!

I try to be smart about the shut downs, and today was mostly suburban driving and was able to see well ahead of my self so I could start coasting early, hate those traffic lights that jump yellow with no cars waiting. I made a few mistakes on the lights today, but did the same as yesterday tracking the amount of shutdowns and the time spent engine off:

26 Traffic shutdowns

15:51 total time shut down

11 sec recoup?(i'd really like to know the real number) = 286 secs

official time off = 11min 08secs

137miles driven today

[Matt Herring]

So in two days you have saved about 30 minutes of idle time...in 4 days that would be an hour saved and 1/4 gallon of gas saved (by your numbers). Saving a gallon or more a month will surely impact your mpg positively over the course of a year.

You have to decide for yourself on it's impact on your starter and if the fuel savings by shutting down the car are most beneficial that any effect it might have on the starter...it's your car at the end of the day...but personally I don't think it's that big of a deal with the starter (again...it's your car at the end of the day).

I went through this process when I started hypermiling too. Was afraid to use higher psi for it's effect on tire wear/traction and slowly inched up from 35 to current 52 psi I'm running. I ran into a guy running 60 psi on the same tires the other day...so I pumped mine up to 52 yesterday. I was afraid to neutral coast in my former 4runner and slowly worked my way into doing it.

You find out what you are comfortable with and do it...what you are not comfortable with you search for more info until you're comfortable doing it or not doing it...certainly a process.

[McTimson]

I replaced the starter in my Tercel last summer. Something in the electrical system wasn't working, so I replaced the battery, alternator, and starter, at around 170k miles. I think the starter was somewhere around $80, and pretty simple to replace.

I don't stop at enough lights to memorize the timing, but the ones that I do know, I shut the engine off.

[Ford Man]

Originally Posted by MetroMPG

Really, when was the last time anyone had to replace a starter?

My '88 Escort with 498K miles and 22 years old is only on it's second starter. I think the original starter lasted about 250K miles , that's lots of starts.

[JacobAziza]

If you buy a replacement starter from an auto parts store, they come with a lifetime warranty.

I've had to replace a couple (long before I started shutting the engine to save fuel), and all you do is walk in with a faulty starter, tell them your phone number (because I had lost the receipt but they keep records in the computer) and walk out with a new starter (also with the same lifetime warranty.)

So for the cost of replacing the starter just once you get a lifetime of starting it at every stoplight.

Originally Posted by cfg83

At extended stops in cold weather, an unheated oxygen sensor could cool off to the point where it is no longer operating normally. The ECU/PCM can detect this state and will spend more time in open-loop mode, which would burn more fuel.

Someone posted here recently pointing out that if you start accelerating immediately after starting, it is irrelevant whether the computer is compensating for the temperature because high-idle/open-loop have the most effect at idle or steady state (low throttle, low RPMs)
How many seconds of idling is equivalent to starting your engine? - IWillTry

[Christ]

Originally Posted by JacobAziza

If you buy a replacement starter from an auto parts store, they come with a lifetime warranty.

I've had to replace a couple (long before I started shutting the engine to save fuel), and all you do is walk in with a faulty starter, tell them your phone number (because I had lost the receipt but they keep records in the computer) and walk out with a new starter (also with the same lifetime warranty.)

So for the cost of replacing the starter just once you get a lifetime of starting it at every stoplight.



Someone posted here recently pointing out that if you start accelerating immediately after starting, it is irrelevant whether the computer is compensating for the temperature because high-idle/open-loop have the most effect at idle or steady state (low throttle, low RPMs)
How many seconds of idling is equivalent to starting your engine? - IWillTry

EGADS Jacob! I forgot about the lifetime warranty...

That brings the score down to "if you can change it yourself, you've only got to save one starter's worth of gas in the WHOLE LIFE OF THE CAR!" (if you don't count your time.)

I'm pretty sure that the average person can save $200 worth of gas in the lifetime of the car (the cost of the Saturn's starter) with not too much problems.

[yanlapanic]

Originally Posted by drewwitlin@hotmail.com

Hey ecomodders,

I've been lurking about reading as much as I can. Tightening the nut behind the wheel was the single most beneficial MPG increase that I have made 26mpg prior to averaging 36mpgs now.

I have been shutting down the engine when I know that a traffic light is going to be long, and have read that it take about 11 secs. for the mpg benefit to set in. While sitting at traffic lights and counting in my head the amount of time the car is off, I figured I needed a stop watch to find out how much time I am off during the day.

Please understand I am a Field Service Engineer for IBM and drive a lot. This is my first attempt to make a contribution to this site.

Honda Accord 2.3l Auto

Todays numbers:

125 miles

27 Traffic light stops with engine shut down.

22:27 Time spent with engine off.

27 restarts @ .11 secs = 297secs inefficient start recoup


so I think I was shut down for 17:30

my scangauge says I burn .25gph at idle.


Is this worth it?


Is this valuable information to be tracking?

what are you talking about ? i want to know if its easy and save gaz !!

and what is GPH ? a mesure of currect draw at idle ?

[cfg83]

yanlapanic -

Originally Posted by yanlapanic

what are you talking about ? i want to know if its easy and save gaz !!

and what is GPH ? a mesure of currect draw at idle ?

Page 8 in the Scangauge manual :

http://www.scangauge.com/support/pdfs/SGIIManual.pdf
GPH = Gallons-per-Hour
LPH = Liters-per-Hour
Fuel consumption rate in the selected units. This is
sensitive to throttle, gear and loading changes.

CarloSW2