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Maximizing Your Truck’s Performance and Mileage

For many people, trucks are more than a way to get from point A to point B. We use them for work, towing race cars, hauling the kids' baseball team, and other tasks that a car or minivan just can't handle. The price we pay for our vehicles' utility is less than stellar fuel mileage.

But all is not lost. Believe it or not, there are things you can do that will not only improve your truck's mileage, but will also bump up its performance as well. We can't promise these products and tuning tips will make your Hemi Ram pickup run 12 second quarter-miles and get the mileage of a Toyota Prius, but you will notice the extra power-and enjoy a measurable improvement in fuel mileage.

It's All About Efficiency
The more efficiently an engine burns air and fuel, the more work it can do per unit of fuel consumed. Translated, an efficient engine can make more power while using less fuel. That's your goal-making your existing engine operate as efficiently as possible.

Since most of the trucks and SUVs we drive are fuel-injected and have a computer-controlled engine management system, we'll concentrate on those types of engines. Here are the key factors we will talk about:
• Air and fuel
• Exhaust
• Ignition and electronics
• Tuners and programmers
• Maintenance
• Driving habits

Air and Fuel
Since a gas engine is basically a glorified air pump, the amount and type of air you feed it is critical to performance. Stock air intake systems are designed to flow adequate amounts of air while keeping sound levels low and costs in check-not a good recipe for maximum efficiency. You can upgrade the factory intake with a high-flow, reusable air filter element; the extra airflow can improve both power and fuel economy.

The next step would be a cold air intake system. It replaces the restrictive factory air intake with a high-flow filter element and a larger diameter intake tube to draw in colder, denser air. Cold, dense air holds more oxygen-oxygen the engine can use to make more power. A cold air intake will improve throttle response and overall driveability as well, and your fuel mileage should increase if you can stay out of the throttle.

Another airflow-enhancing upgrades is a throttle body spacer. A spacer is an easy bolt-on upgrade that doesn't involve recalibrating or parts upgrades. The spacer fits between the throttle body and the intake manifold; most designs either speed up or impart a swirl action to incoming air to increase air velocity. That helps improve low and midrange power and fuel mileage.

Keeping the fuel system, especially the injectors, clean will go a long way to maintaining performance and mileage. Clean injectors atomize fuel better, improving economy and performance. Changing the fuel filter religiously and using a high-quality fuel system cleaner at regular intervals will keep dirt and junk from clogging the fuel injectors' tiny openings. If your performance enhancements are limited to bolt-ons like cold air kits and cat-back exhaust systems, the stock fuel system can handle any amount of additional fuel needed.

Exhaust System
The other half of the airflow coin is the exhaust system. Just like getting more air in, getting more of the spent exhaust gasses out will improve an engine's power and efficiency. The most effective upgrade is a cat-back exhaust system. Like the name implies, a cat-back replaces the factory exhaust from the catalytic converter(s) back. The system features larger-diameter pipes and free-flowing mufflers to better scavenge exhaust gas from the engine. Better exhaust scavenging lets the engine pull a fresh air/fuel charge into the cylinder heads more quickly, which improves both power and mileage. Cat-backs are legal in all 50 states, and one will make your truck sound pretty cool, too.

Another component that affects performance and mileage is the catalytic converter. The converter's primary function is to turn combustion byproducts into relatively harmless CO2 and water. Over time, a converter's core will plug up with contaminants or break apart from the intense heat. A bad cat will make an engine less efficient due to the increased backpressure and buildup of contaminants in the exhaust. While federal law prohibits removing a functioning converter, you can replace a defective one with a high-flow performance converter that is less restrictive to exhaust flow.

While the OEMs have made great strides in designing efficient exhaust manifolds, a good set of tubular headers is more efficient still. While more involved from an installation standpoint, headers in combination with high-flow catalytic converters and a cat-back exhaust will give you a measurable boost in power; in most cases, fuel mileage will remain the same or even improve a bit.

If you notice a drop in fuel mileage and performance around the 50,000 to 75,000 mile mark, the oxygen sensor is the most likely culprit. It monitors the oxygen content in the exhaust stream and sends the information to the Engine Control Module (ECM), which adjusts the engine's air/fuel ratio for maximum power and mileage based on that data. If the oxygen sensor fails, the computer goes into a default mode that uses a richer air/fuel ratio (more fuel than air) to protect the engine from damage. Using more fuel, of course, means poorer mileage.

Ignition and Electronics
A strong, reliable spark is a must for efficient combustion. An ignition that misfires or puts out a weak spark will cost you power and mileage due to incomplete combustion of the air/fuel charge in the combustion chambers. In extreme cases, you will send unburned fuel straight out the exhaust system.

Since the computer controls ignition timing, ignition system improvements are limited to maintenance items like the dsitributor cap and rotor (if so equipped), ignition wires, and spark plugs. When it is time to replace these components, use premium-quality parts or upgrade to performance-oriented parts like high-output coils and ignition boxes.

On-board electronics include the ECM and related sensors. A bad sensor can significantly impact performance and fuel mileage, and even cause engine damage if left unattended. Most sensors are simple “remove and replace" items, but a good diagnostic scanner or code reader is needed to troubleshoot a Check Engine light and track down the offending device.

Tuners and Programmers
One upgrade that can deliver power and mileage benefits with minimal effort is modifying your truck's ECM with a tuner or programmer. They can improve performance by modifying the computer's fuel and timing calibrations; just hook up the device to your vehicle's diagnostic port (it's under the dash in most trucks), choose a tuning level, and press a button. The programmer downloads the desired tune into the vehicle's ECM, and you get better performance.

Power increases can be significant-anywhere from 20 to 100 horsepower depending on the tune selected-and some programmers have a fuel economy setting that can increase mileage by two to six miles per gallon. Most programmers can also reset or eliminate rev and top speed limiters, alter shift points for computer-controlled automatic transmissions, and let you recalibrate a speedometer to compensate for new axle gear ratios and tire sizes. If you decide you want to change the calibration or wish to reset the ECM back to the factory calibration, just hook up the programmer and download the tune you want.

Maintenance
Changing your oil and oil filter regularly is a performance and mileage no-brainer. Clean oil reduces friction and wear, allowing the engine to rev cleanly and run at maximum efficiency. Switching to a good synthetic oil is an excellent idea. Synthetic oil reduces friction and wear better than conventional oil, boosting both power and fuel mileage. Synthetic oil has the added benefit of longer drain intervals.

Don't forget to check things like accessory drive belts, thermostats, hoses and lines, EGR valves, and PCV valves, and and replace them as needed. Check the throttle body and Mass Air sensor (if so equipped) and clean out any carbon deposits. Make sure all fluids are clean and at proper levels. Small things like these have a big impact on engine efficiency.

Your vehicle's tires and suspension also affect performance and fuel economy. For example, tires that are under-inflated by as little as two psi will increase rolling resistance. Since the engine has to work harder to overcome the resistance, it will consume more fuel. Follow the manufacturer's recommended tire pressures; you can find them in the owner's manual or on the decal on one of the door jams. Worn front suspension/steering components and wheel misalignment will also increase rolling resistance and reduce fuel mileage. Things like uneven tire wear, sloppy handling, pulling, and “darty" steering are signs that you have out-of-balance wheels and tires, need a front-end alignment, or require other suspension repairs.

Driving Habits
One of the biggest changes you can make to increase fuel economy is changing your driving habits. Here are just a few things you can do:
• Go easy on the gas and the brakes. Accelerate and stop gradually, and avoid sudden stops and long periods of idling. If you anticipate a lengthy wait, shut off the engine
• Limit warmup times in the winter whenever possible
• Use the air conditioning only when absolutely necessary, primarily on the highway where open windows creates fuel-consuming drag. In stop-and-go traffic or city driving under 30 miles per hour, roll down the windows or use the fresh air vents
• Don't haul around unnecessary cargo. Each additional 100 lbs. of weight you stuff in your vehicle reduces fuel mileage one to two percent
• If you have a pickup, consider getting a tonneau cover for the bed. It can improve mileage by smoothing out airflow over the bed, which reduces drag
• Always use the highest transmission gear possible based on the speed you're traveling. If your vehicle is equipped with an overdrive transmission (most late model vehicles are), shift into overdrive as soon as your speed is high enough
• Plan your trips wisely, especially around town where your fuel mileage is typically lower.  Combine as many small trips (store, gas station, etc.) as possible into one big trip

The glory days of inexpensive gasoline may be behind us, but that doesn't mean we should park our trucks and hide under the bed. Choosing the right upgrades, performing regular maintenance, and paying attention to your driving habits will go a long way to maximizing every tank of fuel you use-and putting some of the fun back in driving. That's not a bad deal at all.