The Comprehensive Guide To Saving Money on Gas

Step 7 Steps 15 & 16 - The Obvious

Drive Less

Obviously this sounds horrible, but it doesn't always have to be. Plan your errands so they can be done with one trip instead of two or more. This is doubly important because short trips are terrible for both your engine and your gas mileage.

Park in the first spot you find. Driving around looking for a better spot takes more time than
walking does, uses a ton of gas, and we could all use the exercise anyway.

Maintain Your Car

Keeping your tires properly inflated, your oil changed, your transmission serviced, your air
filter clean, fuel injectors cleaned, and other routine maintenance can make a huge difference. Any one of those factors if left out of check can hurt mileage by 10% or more.

Comments

[fwater]

"Driving around looking for a better spot...uses a ton of gas" A ton. Wow. How about very, very little. You're driving me nuts! "Keeping your tires properly inflated, your oil changed, your transmission serviced..." OK, good. Sound advice. "...your air filter clean, fuel injectors cleaned..." Oh no, you were so close to getting through a whole step without repeating a falsehood! An air filter would have to be literally blocked off to have an effect on mileage. Why? As a filter becomes more restrictive, the engine knows nothing more than the total flow though the MAS, flowing the right amount of gas for engine RPM, load, throttle position, etc. Less flow through the filter causes you to push the gas pedal further, sucking more air, but having no effect on the engine managements system's calculations, again all based on flow through the MAS. "Any one of those factors if left out of check can hurt mileage by 10% or more." Another statistic pulled out of tin air. I'm sure you believe it, but whoever came up with it has an agenda.

[RickO5]

Wow, just picking apart the article... Okay. Uses a ton of gas: Define a ton? To me, if driving around the parking lot for 5 minutes uses enough gas to get you a couple miles down the road, you're using a ton of gas. Moving around a parking lot, at least in my experience, is nothing but speeding up a little, then almost immediately slowing down, repeated over and over again. As for fuel injectors, you're suggesting a clogged fuel injector will produce the same fuel atomization, power out, and combustion efficiency as a new one? Does that make any sense to you? And as far as air filters go, I can't really do anything but flat out disagree with you there. You are correct, the ecu will maintain proper air fuel mixture, but thats not the point. A dirty air filter does make a sizable difference in economy. I might give you some slack here, if I hadn't physically observed lower fuel consumption rates on vehicles after an air filter change. Guess what that observed change was on the 2nd to last vehicle air filter I changed? Thats right, 10%. I can see why you'd say you say that, seeing as though youre backed by the government fuel economy website. (They do admit that carbureted engines show a difference, but in their cited article they did not measure differences in FI cars) If you havent already, take a look at the article. You clearly have a good eye for picking out problems, you'll find plenty in that one.

[fwater]

I do have a good eye for picking out problems, to the point that I come accross as arrogant or argumentative, this being a prime example. Not my intention; I have simply seen too many unsubstantiated claims. You have shown that you are magnetudes past the average "I read somewhere" guy. I myself have never observed a significant increase from an air filter change. My observations could be affected by- air filters may have not needed replacing, the cars were high performance and had filters with perhaps 100% more surface area than required, or any number of variables logging MPG before and after the filter change. As for the fuel injectors, atomization and pattern will affect power output, but an injector simply running at lower capacity due to a restriction will be corrected by the ECU with a longer pulse width or duty cycle, depending on the system. Let's call it a draw. With the edge to you. Just a slight edge.

[RickO5]

Lower output capacity isn't a particularly a concern. If you ever have the occasion to use a fuel injector outside of a car, try using one that's fouled. A normal injector puts out a nice, even spray. A plugged injector does the same, only with fewer jets of mist. A fouled injector (Im making up this term, Im assuming injectors in this state either have a carbon film on them, or the individual ports are partially plugged) will spray in odd ways. One of the ports might spray a straight, non-misting stream, one might be spraying at an extreme angle, one might be spraying intermittently. I only comment again to say its interesting to see injectors that arent "plugged". Plugged injectors probably dont cause as much of a problem. Id also imagine (guessing) that fouled injectors would be easier to clean, as the solvents can penetrate the individual orifices more easily. Also i should concede Im probably misinterpreting some of my past experiences. Previous to the last air filter change I did (which was just an air filter), I replaced an entire intake system on my brothers car. He's averaged about 3 miles per gallon more (~15% increase) and Ive been attributing that to the air filter, though it could just as easily, and probably more likely be the temperature of the air, which is now coming from a different place in the engine bay.

[fwater]

Yep, changing more than one component can muddy up what really works and really doesn't. Drag racing thing, change one thing at a time when going for that last ounce of performance. Sweeping changes (intake manifold, headers, exhaust) are less important to quantify individually. I would expect a contribution to mileage and power be made by both the filter and cold-air intake in your situatuion. Who knows what contributed to what and how much. I have seen a fuel injector operate in free space when installing a water injection system on my Grand National. It was, of course, unfouled, so I cannot comment. But it looked neat.