measuring fuel efficiency
in [Design]
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From: Jim Thompson on 12 Aug 2010 11:42 On Thu, 12 Aug 2010 16:24:22 +0100, "Michael Kellett" <nospam(a)nospam.com> wrote: > >"Nial Stewart" <nial*REMOVE_THIS*@nialstewartdevelopments.co.uk> wrote in >message news:8chv95Fto3U1(a)mid.individual.net... >>> Oh yeah, certainly the "gallons delievered" read-out is accurate... but >>> if you're doing as Rich says (and this is what my parents taught me to do >>> decades back), it relies on your filling your tank up to the same level >>> as it previously was, and hence the question is how consistent are the >>> auto-shut-off detection devices from pump to pump? (...this is why Rich >>> says to use the same pump at the same station, to avoid this >>> variation...) >> >> >> This doesn't really matter as long as you finish at the same pump you >> started at! >> >> >> Nial. >> >But if you finish where you started the mpg = 0/gallons :-) > >Michael Kellett > Why all this folderol? You keep a log book. Or in Excel. Just list mileage at which you bought x gallons. Long term averaging gives you an accurate MPG. In Excel I actually calculate (1) MPG since last fill (2) MPG average over last 5 fills (3) MPG average over last 25 fills Makes it easy to spot when you need a tune-up... rarely now-a-days. But you can easily spot needs for PCV valve change or clogged gas or air filters. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Spice is like a sports car... Performance only as good as the person behind the wheel.
From: Ken S. Tucker on 12 Aug 2010 12:04 On Aug 12, 3:06 am, "Nial Stewart" <nial*REMOVE_TH...(a)nialstewartdevelopments.co.uk> wrote: > > We have a tachometer, so would it follow that "squirts" are > > proportional > > to rpm, assuming 1 squirt for every two revolutions in a 4 cycle > > motor. > > Not sure though. > > Ken > > It's not just the number of squirts but the squirt duration which is > how the air/fuel ratio is controlled depending on engine speed, > throttle position etc. > > It should be simple enough for the ecu to maintain a running total > of injector on duration -> fuel used. > Nial. Well I think this site is reasonably accurate, http://en.wikipedia.org/wiki/Fuel_injection#Calculate_fuel-flow_rate_... Since the fuel regulation decision made by the computer is exact at any time it seems plausible to have a report from the computer - in real time - it's fuel order. Ken
From: Joel Koltner on 12 Aug 2010 13:47 "Nial Stewart" <nial*REMOVE_THIS*@nialstewartdevelopments.co.uk> wrote in message news:8chv95Fto3U1(a)mid.individual.net... > This doesn't really matter as long as you finish at the same pump you > started at! That's a good point, if you're OK with just having an average over however many miles/fillups you drove in the interim.
From: GregS on 12 Aug 2010 14:13 In article <s2r666tikq13rei7psmgrmsslgakidgidm(a)4ax.com>, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >On Wed, 11 Aug 2010 18:38:37 -0700, "Joel Koltner" ><zapwireDASHgroups(a)yahoo.com> wrote: > >>"Rich Grise" <richgrise(a)example.net> wrote in message >>news:pan.2010.08.12.00.24.08.626089(a)example.net... >>> 1. Fill up the gas tank at a certain pump at a certain station, just until >>> the nozzle clicks off - don't top it up. Record the mileage from the >>> odometer. >>> 2. Drive. Note driving conditions, if desired for more granularity in your >>> mileage assessment. ;-) >>> 3. Fill up again at the same station and pump, again just until the nozzle >>> clicks off. Note gallons. >>> 4. Subtract previous mileage (see step one) from current mileage. >>> 5. Do the math. ;-) >> >>The more interesting question is how accurate the results are with a random >>select of stations and pumps, since this is what the vast majority of people >>use... > >I think station pumps are quite accurate, at least in those states >that penalize heavily for inaccurate delivery... like AZ :-) > > ...Jim Thompson I'm still pissed off. The other day I was fueling at my Giant Eagle Get Go, "supermarket" Got my 30 cents off per gallon. The darn thing shut off and started computing total, and I still had a gallon or two to go. I complained, but that did not work. I didn't hear or feel anything, like it usually does when the air tube hits gas. greg
From: Jim Thompson on 12 Aug 2010 14:22
On Thu, 12 Aug 2010 18:13:14 GMT, zekfrivo(a)zekfrivolous.com (GregS) wrote: >In article <s2r666tikq13rei7psmgrmsslgakidgidm(a)4ax.com>, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >>On Wed, 11 Aug 2010 18:38:37 -0700, "Joel Koltner" >><zapwireDASHgroups(a)yahoo.com> wrote: >> >>>"Rich Grise" <richgrise(a)example.net> wrote in message >>>news:pan.2010.08.12.00.24.08.626089(a)example.net... >>>> 1. Fill up the gas tank at a certain pump at a certain station, just until >>>> the nozzle clicks off - don't top it up. Record the mileage from the >>>> odometer. >>>> 2. Drive. Note driving conditions, if desired for more granularity in your >>>> mileage assessment. ;-) >>>> 3. Fill up again at the same station and pump, again just until the nozzle >>>> clicks off. Note gallons. >>>> 4. Subtract previous mileage (see step one) from current mileage. >>>> 5. Do the math. ;-) >>> >>>The more interesting question is how accurate the results are with a random >>>select of stations and pumps, since this is what the vast majority of people >>>use... >> >>I think station pumps are quite accurate, at least in those states >>that penalize heavily for inaccurate delivery... like AZ :-) >> >> ...Jim Thompson > >I'm still pissed off. The other day I was fueling at my Giant Eagle Get Go, "supermarket" >Got my 30 cents off per gallon. The darn thing shut off and started computing total, and >I still had a gallon or two to go. I complained, but that did not work. I >didn't hear or feel anything, like it usually does when the air tube hits gas. > >greg Some of those auto-shut-off nozzles are downright flaky. And it depends a lot of how your car filler-tube "fits" the "standard". ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Spice is like a sports car... Performance only as good as the person behind the wheel. |