Posted on 04/04/2014 4:14:34 AM PDT by Haiku Guy
The milage in both of my cars had dropped off in the last couple of months. Instead of getting 280 miles per tank, I am now getting 260 miles per tank, or even worse.
I keep a close eye on the milage as a general indication of how my cars are running, but I can't see why this has happened. I have no leaks, no lights, no rough running. I Checked the Engine, and it is still there. The plugs look good.
I think it might be the fuel blend. If that is the case, a lot of people should be seeing the same thing. Before I start tearing things apart, I thought I would ask my friends at FR what they are experiencing.
So how about it? How's the milage on your vehicle these days?
I’m getting tremendous mileage since I installed my new WHAM-O BUMPER GRABBER. I just pull up close behind a car at a stoplight and hit the button and I latch on to that car’s rear bumper. I put my car in neutral and turn off the engine and get pulled by somebody else. I get like six hundred miles per gallon. If we’re not going fast enough, I put on my white hockey mask. They look in the mirror and see me and off we go. I wound up in Oxnard, but I got great mileage.
A clogged or clogging catalytic converter will cause a drop in MPG. It is the first sign. A new Cat Conv = $$$$$$.
If you have the 3.8L V6 the compression ration is advertised at 9.4:1.
I’d say this engine needs 93.
If you run the tank down and refill with 93 you should start to see improved mpg. Then after the next fill up you’ll probably be looking at your steady state mpg with 93. With a little math you can figure out if any increase in mpg is worth the increase in cost per gallon.
I got the ACME version, which includes accessory rocket skates...
I was never a hardcore mechanic but could do OK. But I hardly recognize anything under the hood now either
I recently acquired a CJ7 project jeep and that has enough electrical and electronics for me.
Both cars are about the same age. Maybe that would be a place to look. Is there an easy diagnostic, like back pressure, to check that?
That’s correct. I used to live in Vicksburg, MS. On Saturdays there were up to 20 tankers with different logos parked on the shoulder waiting their turn to load at the local facility. I’ve made it a point to talk to tanker drivers delivering to stations for years to find out where they’re loading. Gasoline is gasoline. The only difference between brands is the additive package.
Oh, I want one of those. Already have the masks needed. I'm going to try different colors of masks after latching on vehicle in front of me with the WHAM-O BUMPER GRABBER. After finding out which mask gets the better gas mileage I'll share my findings. Everything we can do to improve gas mileage and help one another is what FR is all about.
Dang it! I always miss out on the best deals.
I drive a diesel and have noticed a milage slump. Thought it had to do with the studded snowtires.
I don’t think that there is ethanol in diesel.
I drive a diesel and have noticed a milage slump. Thought it had to do with the studded snowtires.
More than likely a combination of things. Winter blend diesel is said to contain less energy per gallon over summer blend, reports of between 4%-10% decrease in mpg. Plus you’re probably running it longer to warm it up in the winter.
+1 on cold weather. More energy required to push through denser air.
I can remember gapping the new spark plugs, gapping the points, replacing the condenser, replacing the distributor cap, wires, retarding/advancing the ignition, using a timing gun, adjusting the carb, changing oil & filter... those days are long over with these new units. Dealers plug them into a computer, it reads all systems, finds ‘glitches’, and indicates modules to be replaced. Meh.
I agree with Perdogg. With this cold winter I’ve seen my gas mileage drop 1-2 mpg. When DC began using 10% ethanol a couple of decades ago my old Chevy Monza (4 spd, 4 cyl. no AC) drop from 31 to 27 mpg on my daily commute.
Have you been starting the car and letting it idle for a bit before driving?
Do you find yourself sitting in traffic more?
I found my travel time increased this winter significantly.
OVer the last year, my mileage has gone from 17.6 MPG to 16.2 MPG, with the same style and amount of driving, and even oncluding a tune-up in that time frame.
Plus you’re probably running it longer to warm it up in the winter.
NO it is garaged. why would something be sold with less in one season than another? Isn’t that lying?
I’d like one. The best I can do is a low geared 65 Willys jeep.
I miss my 67 cougar that I bought from my uncle years ago. Between some financial stuff and a spouse that didn’t like it or me even going out to the backyard to see it or toy with it, it wound up leaving.
However, the composition of the hydrocarbon content in gasoline does change, for two reasons, environmental requirements and economics.
Environmental requirements change from winter to summer, in several respects. But the an important one for mileage is the reduction in light components in gasoline in the summer. these light components tend to cause evaporative emissions and are severely curtailed in summer blends. Light components have fewer pounds per gallon than heavier components. Mileage measured in miles per gallon, is a function of the pounds per gallon of fuel. On the other hand, winter temperatures make the gasoline heavier per gallon than summer temperatures, which offsets this to some degree.
Economically, when gasoline at the wholesale level is worth more than diesel fuel, refiners tend to put some of the molecules that could go into either fuel pool into the gasoline pool. When diesel is worth more, refiners tend to go the other way. These molecules are generally heavier than average gasoline and increase the density of the blended gasoline when they are diverted to the gasoline pool. These heavy molecules are most often from the back end of the gasoline component from a fluid cat cracking unit.
87 octane gasoline generally contains a higher percentage of heavy molecules from the fluid cat cracking unit than does 93 octane gasoline. this increases the pounds per gallon in 87 octane gasoline, which seems to offset the impact of the anti know device “de-tuning” a car running on lower than the manufactures recommended octane. For the past twelve years I have experimented with both 87 octane and 93 octane gasoline in the same car for 1000 miles at a time. I usually achieved about 0.1 mpg higher mileage on the lower octane gasoline, even though the Lexus involved was recommended to use higher octane. Statistically, that is probably not significant. I did not detect any knock.
Density of gasoline can be determined with an API Hydrometer. Unfortunately, this is a bit complicated and requires several hydrometers each calibrated for different density ranges. It also requires a correction to a standard temperature. Hydrocarbon density is generally expressed as “API Gravity,” with a lower number indicating a more dense fluid than a higher number. Here is a link to a Wikipedia article on API Gravity. Included at the bottom of the article are links to hydrometers, instructions for using the hydrometers, and comments on the API adjustments required for temperature. http://en.wikipedia.org/wiki/API_gravity
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