How much fuel does turning the car on consume?

[jcp123]

I'll put in my $0.02: When I start my car, even warm, it idles high for a good 20 seconds...

[iwilltry]

I started a new thread http://www.gassavers.org/showthread.php?t=5586 about an experiment I think/hope anyone with a scangauge should be able perform to determine the "idle second equivalent" of starting their engine. If you have a scangauge (I don't), please give it a try and post results. Thanks.

[slurp812]

Originally Posted by psyshack

In all fairness. Xcel over at cleanmpg just had to replace the starter in his 04 Accord LXE. But his tires are the oem orig. equitment. Im sure he FAS/EOC more than anybody else in North America.

Im sure his restarting just exposed a slightly weak starter in his case. As the mode of failure on a modern starter is stustaned cranking. People that have to crank alot on there cars to get them to start due to poor state of tune or mechanical failuer. go thru a lot of starters.

psy

well my 1994 accord is on its 3rd starter. They seem to go about 75,000 miles each, with "average" starting. I have 170,000 on it now, and expect to replace it again around 225,000...

[8307c4]

I started the engine off procedures sometimes around the year 2,000...
I have yet to burn a starter, thou I did replace one I thought was defective at one point, we're talking 6-7 years here thou...
The only car I stopped doing it in is my truck, the thing has some kind of crazy electrical problem I have yet to figure out... It only acts up every once in a moon, but when it does it has absolutely no power for however long, I've checked everything from battery connections to relays and further. Now the last thing I need is to get stuck with a 32-foot thing at a busy intersection, I can't even push it out of the way, so that vehicle I don't do it anymore.

But everything else, probably done did this a few thousand times by now...
And for those folks who think fuel hogs can't hypermile, those are the best vehicles to do it in! At a consumption of 10mpg, if I can increase this to 12mpg it's still a 20% fuel savings, I go from a cost of 30 cents / mile down to 24 cents / mile just in fuel.
My first 3/4 ton truck I brought from 8-10 mpg all the way to 14, those were the days but most of the procedures back then are so standard to me nowadays that by the time I get a vehicle I'm already halfway there so the increases aren't as noticeable.

I'd say it depends, fuel maybe 1-2 ounces, maybe 5-10 seconds worth, if that.
Even bigger engines, we're talking mere ounces to start it.
All cars dump extra fuel into the engine for starting yes, but not for more than a few revolutions, once it fires it's over, we're talking a half a pint max for a very cold large truck engine, probably more like 3-4 maybe 6 ounces, a shot glass. For warm engines, maybe an ounce or two, if any.

It's not the cost of the fuel alone that needs to be considered when turning the car off.
It's more wear and tear on the engine, and the starter as well.
These costs, specifically starter replacement and engine wear, must be considered.
So for one, I run synthetic oil.
All in all, 20 seconds off time minimum, by 30 it's paid off for sure.

Other notes: one gallon = 128 ounces.
And no, a diesel consumes little fuel idling, I think this is mainly for gassers.

[DarbyWalters]

I've done both but I think with a Diesel...idling and coasting are not a big fuel consumption factor as with a gasser. The wear and tear on the starter and transmission are probably not worth the minimal savings with a automatic diesel. When I coast the revs drop right down to 750rpm and with a diesel it is not really adding much fuel at all without input from the pedal. Unless I know that I am going to be sitting inline for 2 minutes or so...I just clatter away.

[2TonJellyBean]

Darby, if you're running a ScanGauge could you tell us the idling consumption for your CRD?

[GasSavers_Minger]

Hmm...this is interesting. Usually, coming back from school, I get an average of ~30-35 if I'm lucky...a lot of hills and whatnot...

But today, (I've done this a few tiems before I got my scanguage) I did a P&G about 3 times, probably 30-40 seconds each time...and it read out at about 40mpg. Maybe its too much to do it at the end of a 5 mile trip 3 times, but it worked...bleh for automatics!

[DarbyWalters]

Originally Posted by 2TonJellyBean

Darby, if you're running a ScanGauge could you tell us the idling consumption for your CRD?

I will be doing some work this weekend on the Diesel and using a different kind of setup that will give me that information.

http://www.autoenginuity.com/

A member of my forum at www.LOSTKJs.com has one of the in the "enhanced mode" and we will be running some tests with it this weekend. I will get some good info I hope.

[skewbe]

http://www.google.com/search?hl=en&q...engine+seconds

It looks like the consesus is 10 seconds. I've heard figures from 5 to 8 seconds, so it is probably car dependent, but it isn't much in any event. You just have to put in enough energy to get the engine spinning again, it shouldn't need extra fuel if it's been running (do you re-prime your lawnmower after stopping it briefly)

[iwilltry]

skewbe, have you thought of using your "audio-in laptop oscilloscope" and getting your program to look at cumulative pw vs time just after starting? If you plot cumulative pw vs time then the idle time equivalent of starting should become very clear. It could even be displayed automatically every time you start the car. See image for an explanation. Don't know why scangauge hasn't thought to do this.

This gives the "equivalent FUEL consumption idle time" which will be lower than the "equivalent COST consumption idle time" due to additional wear. But at least it gives a solid lower limit based on empirical data for one's own vehicle instead of a consensus value based mostly on the opinions of multiple vehicle owners. I've heard lots of claims, but have yet to hear anyone explain how they determined their results.