Under the Hood: E-85 fuel only suitable for cars designed for it
QUESTION: I see E-85 gas at locations in Pennsylvania. I have a 2011 Chevrolet Cruze with 30,000 miles on it. I put regular gas in my car and usually fill it with a tank of premium every 4,000-5,000 miles and have the usual maintenance done. Is using this gas OK, or will it affect the engine?
ANSWER: E-85 is an environmentally friendly, lower-priced alternative to conventional gasoline. Conventional gasoline is typically E-10, which is 90 percent gasoline and 10 percent ethanol, a renewable fuel made from corn or other plant material. E-85 is up to 85 percent ethanol and a proportionally smaller gasoline percentage. As you have noted, E-85 can be purchased at a lower cost than E-10, but fuel economy will be about 30 percent lower, possibly erasing the cost advantage.
GM and Ford are strong proponents of E-85 and build large numbers of flex fuel vehicles each year. These cars and trucks have more robust fuel system components, which helps to resist the corrosive effects of E-85, and the smarts to adjust to any mix of conventional gasoline and E-85. To the best of my knowledge, your Cruze is not designed for E-85 – you'll want to check for a yellow gas cap and filler door documentation to be sure. If it is not E-85 capable, I'd strongly recommend against trying the fuel. Yellow-cap owners may consider the pros and cons of usage.
Q: I have a 1981 Buick Century with 71,000 miles. It runs pretty well except for one problem that has been bothering me for the past few months. When first starting in the morning, it stays on fast idle for about 10 minutes no matter how many times I tap on the gas pedal. But after 10 minutes, it idles normally.
A: General Motors engines of this vintage used a carburetor equipped with an electric choke heater. The heater was a big improvement over previous schemes to provide exhaust or coolant heat to the choke's thermostatic coil, and typically gave very little trouble. The fast idle linkage is enabled by the choke linkage, so it's possible your engine is also running very rich – wasting fuel and unnecessarily polluting – until the mechanism unwinds due to engine heat. I'm guessing either the heater is not working or the mechanical choke-fast idle linkage is dirty or sticky.
I'd start by purchasing an aerosol can of carburetor cleaner, such as Berryman's B-12 Chemtool. Next, with the engine cold, remove the air filter housing, being careful to notice and disconnect the single black vacuum hose attaching to it. Standing upwind, holding your breath, apply a 10- to 15-second shot of B-12 to the linkage on the passenger's side of the carburetor (behind, above and below the round black choke heater housing) as well as the choke plate area atop the carburetor, approaching from a variety of angles. Next, try gently wiggling the linkage parts, checking for sluggish movement. Also verify the single electrical wire leading to the choke heater is connected.
Reinstall the air filter and try the Buick for a day or two. If it's better, we'll count our blessings. If the symptom remains, professional testing of the choke heater and its circuit would be my best suggestion.
ABOUT THE WRITER
Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, Calif. Readers may send him email at firstname.lastname@example.org; he cannot make personal replies.
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