This is part 2 of the series Fuel economy tips for better mileage.
8: Get a dynamometer tune
Some car buffs visit dynamometer (dyno) shops all the time for real-world dyno tune performance in their quest for power. But did you know a custom dyno tune can also improve fuel economy? The key is to communicate what you want from the dyno tune. By recalibrating fuel and spark curves, fuel economy can improve along with power. What’s more, a good dyno shop can also find trouble items that require attention, such as O2 sensors, malfunctioning fuel injectors, a misfire and more. Do be sure that the work is done properly and that it doesn’t void your manufacturer’s warranty.
9: Sticking EGR valve
The EGR valve gets very little notice until it fails. And when it fails, it can cause a rough idle or an engine that won’t idle at all. The EGR valve cycles open and closed based on throttle movement and intake manifold vacuum to reduce exhaust emissions. If it sticks open due to carbon deposits and heat distortion, it creates a vacuum leak and rough operation. This will adversely affect fuel economy. Check your manufacturer’s recommendation for replacing the EGR valve.
10: Evaporative emissions
Your vehicle’s evaporative emissions control system indirectly affects engine function and fuel economy. The evaporative emissions system consists of vacuum hoses, a charcoal canister, and purge solenoids. The job of evaporative emissions is to trap fuel vapors in the tank and route them to the engine to be burned. With time and use, hoses become dry-rotted, the canister becomes contaminated, and purge solenoids can quit. If your vehicle has over 100,000 miles, check these parts and follow your manufacturer’s recommendation. You can replace 100 percent of the evaporative emissions system every 100,000 miles. This is the environmentally responsible thing to do and it will indirectly help fuel economy.
11: Fresh spark plugs
The “100,000 miles between scheduled tune-ups…” manufacturer’s claim has made us negligent. We believe automobiles are maintenance free aside from worn brake pads, tires, shock absorbers and filters. However, spark plugs should be replaced every 50,000 miles. Oh sure, you can get away with 100,000 miles and even more on a set of platinum tip spark plugs. However, as high-energy ignition systems hammer away on the cross electrodes, the gap gets wider and the spark less consistent and intense. Get yourself a fresh set of spark plugs for better gas mileage. And while you’re at it, check your coils and ignition harness.
12: Vacuum leaks
Vacuum leaks are easily one of the most overlooked malfunctions because we tend to think the worst and miss stray suckage completely. Oftentimes, vacuum leaks defy detection. Because so many operations beneath the hood depend on intake manifold vacuum, there are seemingly miles and miles of vacuum hoses from bumper to bumper. Vacuum hoses dry rot, as do tees and other unions. And when they do, they create vacuum leaks, which can upset the electronic engine control system. O2 sensors pick up on lean conditions and enrich the mixture to compensate. You get a rough or unusually high idle and less power. The result is poor fuel economy.
13: Fuel pressure regulator
Fuel pressure regulators are typically life-of-the-vehicle components, but they can fail. Check your manufacturer’s recommendation, but it’s a good idea to change them every 100,000 miles to keep fuel pressure in the ball park and your vehicle on the road. A failed fuel pressure regulator can cause either too much fuel pressure or none. Too much means high fuel consumption and poor performance.