Your engine is just like a big air pump, it’s job is to pump air. In the process your engine adds in some gasoline and lights it on fire. You need to make sure that the air is moving in and out of the engine with little to no restriction, and you need to make sure that all the gas that goes in gets burned. If you can do this, your engine will be as efficient as possible.

Air enters your engine through an air filter. The filter is designed to keep dirt and other contaminants out of your engine, which prevents premature wear. Most stock air filters are a compromise between their ability to filter and a longer service interval. New cotton filters from companies like K&N perform much better than your stock filter and can last the lifetime of your vehicle. There is one trade-off, you have to clean and oil the filter at a set interval. It’s best to do this at every oil change to keep your filter operating at peak efficiency. This process can be done with a hose and the special oil provided with the filter.

Once the air has entered your engine, it travels through the throttle body and into the intake. Overtime your throttle body accumulates carbon buildup and needs to be cleaned. If your engine has over 50,000 miles, I would get a can of throttle body cleaner and clean it. This can help how your engine idles and keep your engine operating at peak efficiency.

Your engine cannot run on air alone, and this is where the gas comes in. Just before entering the cylinder, the air gets a shot of gas from the fuel injectors. If your fuel injectors are clogged or stuck, too much or too little fuel will be injected. Regular use of a fuel injector cleaner added to a tank of fuel, can keep your injectors operating like new. If you have over 100,000 miles and have not used a fuel injector cleaner in the past, your mechanic can clean the injectors and most likely get them back to as-new condition.

Now that the air and gas is in your cylinder, the engine fires a spark plug to light the volatile mixture. This happens many times per second and in order for it to happen properly, your ignition system needs to be in good condition. If your spark plug wires are cracked or damaged, they can leak voltage to the engine block and prevent the spark plug from firing completely, or not at all. This can allow unburned gas to exit the engine and reduce the efficiency of your engine. Inspect your spark plug wires for signs of cracking or arcing and replace if you see any damage. Your engine’s spark plugs lead a tough life. They have to endure super high temperatures and very high voltages. The spark plug has an electrode and ground strap, which is separated by a specific distance. This distance is called the plug gap, and can widen with time as the two parts wear. As with air filters, auto manufactures compromise on spark plugs and make them last a long time but lose some efficiency. Most newer spark plug electrodes are made from Platinum, which wears like iron, but does not conduct electricity as well as copper. Older style copper plugs work better, but do not last as long since copper is soft compared to Platinum. I do not suggest you switch to copper plugs, but I would suggest changing plugs sooner than the recommended interval just to be safe. If your service manual suggests changing spark plugs at 75,000 miles, I would change them at 60,000 miles just to be safe.
In the next article I will discuss how your driving style can increase your gas mileage and save you even more money.

Kevin Schappell runs www.AutoEducation.com where he gives advice on auto repair, maintenance and car care. If you would like to comment or ask a question you can email him at Kevin@AutoEducation.com

Myth #1: Buy gas in the morning when the gas is cooler, thus denser.

Gasoline is stored in underground tanks, which remain at a fairly constant temperature. I have personally reviewed the tank readings at my local gas station to confirm this fact. It’s like a cave, which stays at a constant temperature all year long due to it’s distance from the surface of the earth. The only factor that comes into play, is when the gasoline is delivered to the tank. When gasoline is transported in trucks, it will expand with heat. If you buy your gas right after the tank is filled, you will receive warmer gas, but I would not stake out your local gas station to find out when the gas truck delivers.

Myth #2: Driving with the windows down at highway speeds without A/C is better than windows up with the A/C on.

When at highway speeds, keep your windows up. On most vehicles, having the windows open at highway speeds will create extra drag and cost you gas. If it’s a hot day, running the A/C is a necessary evil, and will cost you gas mileage, but the loss is about equal to keeping the windows down on most cars. When driving under 45mph, keeping the windows open and A/C off will be more economical because drag from having the windows is not in effect at the lower speeds.

Myth #3: Keep your engine running if you are making a quick stop at the store, it takes more gas to start your engine than to leave it running for a few minutes.

This myth is not true, starting an engine takes very little extra fuel, and it is always better to turn the engine off.

Like anything in life, cheaper is not always better. When it comes to buying gas there are a few things to remember.

Name brand gasonline generally has more detergents, which help your engine run cleaner and more efficiently. I personally use Texaco due to some personal experiences and the fact that I used to work at a Texaco station in high school and college. At the time, the regular gasoline did not have the same additives as the plus and supreme grade. I switched from regular to plus grade, and got better gas mileage. I was driving a 1979 Mustang at the time with a 4 cyl. engine and went from 18 to 20 mpg just by switching grades of gas.

To find the lowest prices, there are websites online, which post almost real-time gas prices across the country. I would also shop at gas stations, which have competition, which will drive prices down. So the more gas stations in the area, the better the price.

When you are at the gas pump, start the pump and then take a walk around your vehicle. You should check all 4 tires for any signs of low air pressure. In all but the higher performance tires, you can see the sidewall of the tire bulge when air pressure drops. Once per month I would check the tires with a quality tire gauge to be safe. Low tire pressure can create more rolling resistance and will hurt your gas mileage. If you are not a good judge of tire pressure by looking at the tires, consider a cool new product on the market that replaces your valve stem cap. It shows green when your tires are at the proper pressure, and red when they are low on air.

Safe Driving,

Kevin Schappell

Before we get into how you should drive for the best gas mileage, let’s talk about what you should do before you leave the driveway. The first thing you should do, if it’s hot outside, is turn off you’re A/C and roll down the windows. This will reduce the load on your engine, and clear out the super heated air that has built up in your vehicle. Once you are above 45 mph, roll up the windows and turn on the A/C.

We can now start our discussion on driving style and discover how you can save up to 33% on gas. The first thing to think about when driving is conservation of momentum. Consider the following two scenarios…

1. You are driving along at 45 mph and see a red light ahead. You wait until the last second and slam on the brakes, then accelerate away when the light turns green.
2. You are driving along at 45 mph and see a red light ahead. You let off the gas pedal, and coast into the light, while anticipating when it will turn green. If you time it right, you never stop and continue on your way, ahead of where you would have been in scenario #1

This type of thinking in scenario #2 will put money back into your pocket. Your brake pedal is your enemy when trying to get better gas mileage. If you can anticipate traffic ahead of you, and avoid having to push on the gas pedal hard, you will save gas. Any time you use the brakes, you are losing momentum and wasting energy.

I had a friend in high school, whose dad put a vacuum gauge in all of his vehicles. A vacuum gauge in simple terms, measures the load on an engine. It served to remind my friend’s dad how he was driving, and forced him to go easy on the gas pedal to save gas. Consider having your mechanic install one of these gauges, the cost is minimal, and you may learn a little about how you are driving. If you have a newer car with an advance engine computer, it may tell you your instant and average mileage. Use the instant gas mileage readout instead of a vacuum gauge, it’s just as good.

You want to accelerate as mildly and evenly as possible to get to your desired speed. If you have a tachometer in your car, you can watch engine RPM and try to keep it under 3,000. You should be able to get to your destination in a safe and speedy manner, using these techniques and save some gas in the process.

There has been a lot of debate about what is the best speed to drive on the highway. Politics and safety issues have clouded the issue even further. The fact is that every car has it’s own speed where peak efficiency occurs. I had a Corvette that got the best gas mileage at 70 mph. It’s not practical to drive this fast everywhere, so I compromised and kept it legal as often as possible. Depending on your engine, transmission and gear ratio in the axle of your car, you ideal speed will be higher or lower than my car. The most important fact to remember is to keep your speed steady and avoid abrupt stops and starts.

I have heard various automotive journalist report better gas mileage by not using the cruise control. There reasoning was that they were focused on driving for efficiency and could make better decisions that the cars cruise control computer. This theory is valid, if you are on a highway with a lot of elevation changes. If you are not using cruise control, you can allow your vehicle to coast down long hills and build up some extra speed, which will help you climb the next hill. Of course you need to use some common sense here and not allow your car to go too fast to avoid speeding tickets or dangerous driving conditions.

The last tip I can offer on driving, is make your vehicle as light as possible. The lighter your vehicle, the less you engine has to work to move you around. Remove any unnecessary items from the trunk and car to help keep your car as light as possible.

The gas door and cap were accidentally left open when going through a car wash. The tank had just been filled up and it looks like there is a metal door that is closed unless a fuel pump is inserted. What problems may occur and is there something that should be done?

Karen

Answer:

Karen,

I would put a bottle of “Dry Gas” or similar gas line treatment that removes water, into the tank immediately. The alcohol in the treatment removes the water from the gas tank. If you experience sputtering, or poor performance after the treatment, I would have the tank flushed at your mechanic. More than likely, not much water entered, since the tank was full, and the flap in the filler neck should have prevented some of the water from getting in.

Kevin

Hi, I was wondering why fuel is leaking out of my carburetor? When it is running it started as a drip at first and now it is leaking heavily. Would a carburetor kit fix that problem? And what comes in the kit?

Another question is, is it normal for oil to be in my radiator or is there a serious problem that needs attended to right away. i have a 1986 Ford Ranger pickup it has A 2.0 4 cylinder engine i barrel carburetor please help any help would be appreciated thanks.

Answer:

A rebuild kit may help, but the leak may be from a crack in the carb too. I would remove the carb, look for any broken or leaking gaskets. Sometimes there are plugs in the bottom of the carb which can come loose. Carb kits usually have gaskets, float, needle and seat. If you floats are leaking, or the seat is worn, it will cause a flooding condition and you will see fuel leaking.

Oil in the radiator, indicates a leaking head gasket. I would get it checked/fixed ASAP before it turns into more of a problem. A competent mechanic can do a compression test and check for a bad head gasket.

Good luck,

Kevin

Kevin