Better gas mileage?

[jerryjetman]

I am looking for info on getting better gas milage on my 02 Forester, 85K miles on the OD.I have done all I could to increase gas mileage, Platinum plugs NGK, Mobile 1 oil, synthetic gear oil in diff and rear, tire air pressure 35lbs, K&N air filter. Carefull driving habits no jackrabbit starts etc. My best mileage is 24.6 average (8 miles on surface roads and 11 miles on the highway) back and forth to work daily.Any hints out there ?? I found a company on the internet that sells a chip that goes into the IAT module.I purchaced the chip which was actually a 35K ohm resister. I sent it back and did not try it. I was afraid it might of mess something up. Can anyone help me with this or am I doing all I can ?

Thanks jerryjetman

[86subaru]

sounds like you have done alot, i have heard do not use the chip, or magnets on the fuel line, i only get 20 if iam lucky, but only 5 miles to work and back ea day,

[nipper]

Remove the cross bars on the roof rack.

 

I found a big help (or eye opener) was a scangauge. Sometimes there is no rhym or reason that i can figure out. Sometimes Blu will get 24 on the highway, sometimes 32. Around town is 16-21 (low end if its really short trips).

 

 

nipper

[mnwolftrack]

It sounds like you've covered your bases, and there isn't much left that you can do. A few more things might be to remove all unnecessary items cluttering up the inside of the car (some people carry a lot of stuff!) that adds weight. Drive the speed limit or slower (55mph). Wind resistance increases exponentially with speed. Don't use an aftermarket ski rack. If you have a factory roof rack, see if you can take the cross members off easily to further reduce wind resistance. I'm not sure how the forester roof rack attaches (I've only owned outbacks) but they might come off easily. If you have a tow hitch but don't ever tow anything, take the whole thing off.

[jerryjetman]

Thanks for all of the input.

[jerryjetman]

What is a scangauge?

[nipper]

http://www.scangauge.com/

[jerryjetman]

Thanks for the info on scangauge looks, pretty interesting....never heard of it before.Will check it out for sure

[nipper]

Actually 24.6 is pretty good for a brick on wheels

 

nipper

[aircraft engineer]

It would take a LOT of input to justify $170 for another techtoy system. Even if it gets you 1 mpg, that's 4% or roughly .8 gallons per 20 gallon tank - run dry at $3/gallon it's $2.50 (round number to keep the math simple) so that's 68 tanks to pay it off - at 400 miles/tank, that's 40,000 miles more or less. Of course, it will payoff faster if the price of gas goes above $5. Trouble is - it just TELLS YOU STUFF - IT DOESN'T DO ANYTHING "ACTIVE".

 

I'll wait for the cheap Chinese copy.

 

Lighter cars (like the IMP) get better mileage simply because they don't haul the extra weight around. The 24.5 is about right, actually. Any calcs on what you see on long distance driving (hiway)? I'd guess 27 or so, maybe 27.5

 

Not that it would help you much, but I used to have a "can" that had a heater hose attachment in/out and a fuel line that passed thru the can in a coil. When the engine heated up, the fuel going into the engine was warmer and expanded. Since the injectors (old carb system in this case) work on volume, the amount of "energy content" going in was "less" so the mileage went "up" as well. The prime problem was "vapor lock" (usually at idle). Injector systems with a fuel return line might take care of that issue by keeping the fuel "liquid" at all times.

[jerryjetman]

I do not think of my beloved 02 Forester as a "brick on wheels" . If any thing it would be " omni stone on wheels" ( a fancy name for a brick) HA HA

[OB99W]

[...]Since the injectors (old carb system in this case) work on volume, the amount of "energy content" going in was "less" so the mileage went "up" as well. The prime problem was "vapor lock" (usually at idle). Injector systems with a fuel return line might take care of that issue by keeping the fuel "liquid" at all times.

Assuming the engine management system (ECU, O2 and other sensors, etc.) is working correctly, all that will happen with a modern car by using "less dense" fuel will be that the fuel trims will change to compensate. It won't run any leaner, so no MPG improvement results.

 

Jerryjetman, the mileage you're getting seems to be close to what might be expected. Terrain (hilly versus flat), traffic and number of stops, weather conditions, "winter" gas, individual driving habits, etc., obviously all play a part in how far a full tank gets you. You seem to have already done much of what could be. One thing here in the Northeast that sometimes is a problem is corrosion at the brakes; slight dragging that isn't otherwise noticeable can cost you up to about 10% in MPG. (You'd probably notice any brake problems that would affect the mileage by more than that.) I assume that Pittsburgh uses salt on the roads in winter -- if so, it might make sense to inspect the brakes and be sure that everything is free to move. For example, it's not uncommon for brake pad "ears" to stick in calipers.

[garthpro]

Not that it would help you much, but I used to have a "can" that had a heater hose attachment in/out and a fuel line that passed thru the can in a coil. When the engine heated up, the fuel going into the engine was warmer and expanded. Since the injectors (old carb system in this case) work on volume, the amount of "energy content" going in was "less" so the mileage went "up" as well. The prime problem was "vapor lock" (usually at idle). Injector systems with a fuel return line might take care of that issue by keeping the fuel "liquid" at all times.

 

This is an interesting note, as I have seen the mileage in my '00 OBW skyrocket in the South on summer trips when the ambient temp is in the 90s. I have recorded tanks at 30-32 mpg(all Interstate, no stops) some of that with AC on! when earlier in the day up north I was around 28 (same all interstate NO AC!). I do a lot of driving and long xc trips for mtb'ing. I thought it might have something to do with fuel temps, but was unsure.

 

Does anyone else have similar results?

[OB99W]

This is an interesting note, as I have seen the mileage in my '00 OBW skyrocket in the South on summer trips when the ambient temp is in the 90s.[...]I thought it might have something to do with fuel temps, but was unsure.[...]

It does have to do with fuel temps, and other factors. Gas at the stations is almost always stored in underground tanks, where it's cool. That gas expands in your car's tank, so effectively you get "more" gas, which will have some effect on apparent mileage. It's also likely that the viscosity of drivetrain lubricants will be lessened in the heat, resulting in lower frictional losses.

[mdjdc]

Gas mileage on warm days has alot to do with the air temp as well. When the air temp is lower, the air is more dense and therefore more is going into the intake. More air requires more fuel and thus the mileage will go down. Hot days, less dense air and less fuel. Higher mileage. It all has very little to do with expansion of the fuel in your tank and apparent higher mileage as a result. It is mostly a function of air density and the ECU fuel needs as a result.

[idosubaru]

in the 90's when i used to drive 40k a year on long highway trips i recall getting better gas mileage in the colder winter months. i don't notice that any more...maybe it was just that car or new gas or i couldn't divide as well back then!

[nipper]

in the 90's when i used to drive 40k a year on long highway trips i recall getting better gas mileage in the colder winter months. i don't notice that any more...maybe it was just that car or new gas or i couldn't divide as well back then!

 

Fuel injection has made up for a mulititude of sins.

 

nipper