Improve MPG

I was thinking the same thing but I think what he's saying is that because the pump can stop anywhere from 1-3 gallons short, it'll affect the calculation (not the actual MPG).

So for example, suppose I think the tank is full but it's really 3 gallons short. Thinking it's full, I drive until it comes time to fill again but this time the pump shuts off only 1 gallon short. I've pumped in an extra 2 gallons so it'll make my mpg low for that calculation.

For a one time calculation it would be off but it should average out over many tanks.

 

That's true. The manual and automatic 6cyl have different gear ratios. My manual's rpm at 65 is about 2500 whereas an automatic is usually below 2000 rpm at that speed.

 

Here's the problem, for example let's say you drive 400 miles and fill up with 20 gallons of gas at your favorite gas station because that's where the pump handle clicked, 20 mpg. Next tank 400 miles, same gas station but different pump, and the pump handle clicks at 17 gallons, 23.5 mpg. Given the same sort of daily driving and technique you've artificially raised you mpg by 3.5 mpg, because the pump stopped early. The results aren't consistent. If I couldn't explain the discrepancy such as a change in seasons, city vs highway, etc. I'd be looking for the cause.

^^^What evil monkey said.

 

Ah ok, good point.

 

This is another reason why I'm anal about not just where I get my fuel but which pump I use. If your truck isn't level when you pump the tank won't be level, this will change how much will gas you can stuff in the tank. At the very least, when possible, I've eliminated one of the variables by going to the same pump and station.

 

Ok well we all need to just get scangauges! I fill up at a chevron and used the same pump every time (When I am in this area). Does that consistency negate the possible error you pointed out?

 

Consistency will help but isn't full proof, remember hundreds if not thousands of people will be using the pump while your out driving around. If the station decides to replace the pump handle it will click off at a different time than the old one.

Having a consistent techinque will limit your variables, which is the goal, the only variable we want is how much gas goes in the tank. Experiment a little, the next time you fill up when the pump clicks look at how much you've put in then add .5 gallons, if there are no ill effects add a full gallon during the next fill up. Be nice to the pump handle you don't want gas to splash back out of the fill neck, trickle the gas in. The Taco is really easy to watch this happen.

That being said you can "overfill" a tank on newer vehicles. I've done this to an '05 civic, and '99 ranger. Here's what happened, the ranger being a bit more rude and crude started with no problems, then .2 mile to the on ramp, the on ramp was down hill followed by a quick up hill segment at full throttle, big demand on the fuel system. The fuel system didn't like that with full fuel, the engine started to surge, cut in/out, it never shut down. After 2.5 miles enough fuel was burned and everything smoothed out.

After thinking about it some I realized my mistake, not only did I fill to the cap but rocked the side of the bed to get more air out and put more fuel in. I've never had an issue since. I've had the truck since may 02 43000 miles now have 121000 on the odometer.

The Honda was cool in comparison. I just picked up the car from my parents place in Dayton, OH and was driving back to Grand Forks, ND about 1040 miles. I've owned the vehicle for about 4 hours at this point. First fuel stop I did what I've always done, fill to the cap, but also aware that this might cause some issues. The tank on the Civic for some reason isn't as straight foward as the pick up trucks. I didn't follow my techinque and rocked the trunk lid, bad idea. I didn't even get out of the gas station and the engine started surging. I parked and set the park brake and waited. I revived the engine to burn more fuel, the ECU was having a hard time controlling rpm, the idle was erratic. After about 10-15 minutes the idle stabilized and I no longer needed to control it with my foot. I motored away with no more problems.

I've slowly worked up to the max fuel I can put into the Civic without "overfilling". It still comes up the cap but unlike the Taco the filler neck is harder to see.

Here's some tips for consistency:

1. Fill on a most level surface you can, a lot of gas station pump locations can be far from level.

2. Use the same pump if possible.

3. Use the same grade of fuel everytime, brand if possible.

4. Whatever technique you come up with stick to it, and don't let your significant other fill your truck for you, they won't have the same technique unless they're as screwed up as you.

It's still my belief/opinion that the only way to get accurate fuel numbers is to fill to the cap, the biggest variable being that stupid pump handle which can click off whenever the hell it feels like it, no matter how consistent you are on your end.

I can e-mail you my complete ranger fuel log for reference if you'd like.

 

Actually a scangauge wouldn't eliminate that error. With the scangauge you're supposed to calibrate it every fillup with the amount of fuel you put in at fill time. You'd be introducing the same error into it's calculator.

 

Well said, I proved this myself... I used to drive on the highway with the tailgate down all the time--thinking I was saving on gas. Last month I left it up on a long trip and got way better MPG.

 

Here's the link to actual wind tunnel testing and it's effects with the tailgate up and down, and tonneau covers full and partial:

http://ecow.engr.wisc.edu/cgi-bin/ge...hi1/pickup.pdf

This was posted only a couple of weeks ago, the tests date back to 2004 but the results are still applicable.

 

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Ah its hopeless!

 

I found the old thread:

Ye Olde Tailgate Debate

Started by Brunes, 5/2/09, the link is on the first post.

 

What's better dropping the tail gate? or taking it off completely... I might take mine off it anything else.

 

I'm confused.........Why did you purchase a p/u??? to use the bed and play.it is a truck.......you want 54 mpg's...Prius and no it does not come as a 4x4.

The best thing for mpg's,how YOU use that right foot....My Camry V-6 turns excellent mpg's when I use the cruise instead of my "Lead foot"...the Taco's 4 banga does the same...both in town or highway....

Maintenance will help more than a missing gate....keep "IT" clean,that mud from the weekend takes more rpm's to turn ,that air filter system needs AIR,letting it growl ( breathe) with some back pressure means powa but also efficiency,raw gas out an exhaust is wasted...

Sorry to "rant' BUT "Old School" does work...drive it like a racecar,get race car mpg's.drive it smart and it shows $$$$$..( for some that means more toys)

Snoope

 

Is this road flat?, i mean, maybe on the way back you was going down, and that could help your mpg's, wind is another factor that can be involved.I think a better test shoul be done in the same way, and with similar weather.

I don't trying to invalidate your test, i only saying that there are some variables that can help or hurt your mpg's other than the tailgate.