strong>Dear Doctor: I have a 2015 Chevy Silverado long wheelbase regular cab pickup truck with 20-inch wheels. It suffers from what the service manager describes as "Chevy shake." We discussed the shocks, tires and driveshaft, but changing them and doing a wheel balancing didn't help. The service manager has a 1/2 ton four-door truck with the shake and says General Motors admits to this intermittent highway speed shaking problem -- but they do not have a fix for it. Several of my friends with these Chevys have the same problem. Have you heard of it? George
strong>Dear George: You're not the first owner to experience a shake or vibration on some 1500 pickups. I have seen it all over the years. Transmission and torque converters are the most common issues that cause a shake. Very seldom it is axle-related.
strong>Dear Doctor: I have a 2008 Chevy Silverado V-6 with 120,000 with a slight hesitation. My fuel mileage has dropped from 16 mpg to 13 mpg. The plugs/wires were changed at 80,000, and then again at 110,000 miles due to hesitation. When recently removing the iridium plugs I noticed the gap was substantially larger. The new plugs help but there's still hesitation, unless I use premium fuel. This truck has a "non distributor" ignition (there's no cap to change). Should I change the coil or spider injectors? Anthony
strong>Dear Anthony: Your first step is to perform a full-engine diagnostic series of sensor values. Hesitation can be caused by any number of worn or dirty fuel-injected input sensors. It takes the entire system to function correctly. With this said, a lazy oxygen sensor, dirty mass air-flow meter, low engine temperature, low fuel pressure or restricted fuel filter, early opening EGR valve, even carbon build up on the valves can cause problems. The use of premium unleaded gasoline burns hotter and slower than the regular 87 octane gasoline. There could even be a small vacuum leak in the system.
strong>Dear Doctor: I just purchased a brand new Chrysler 300S equipped with the 5.7-liter V-8 engine. It has a Multi-Cylinder Displacement System that shuts down cylinders based on engine load. Does the Multi Cylinder Displacement System cause excessive wear and premature failure of top engine components? Chuck
strong>Dear Chuck: There is no harm in cylinder deactivation, and many automakers are using deactivation as a way to improve fuel efficiency on at highway speeds when not all cylinders are needed. However, some car owners do complain about it, as they do about transmission lock-up converters and occasional bucking.
strong>Dear Doctor: What do you know about a new car from Hyundai called the Kona: Maureen
strong>Dear Maureen: I do believe Hyundai is building some of the best cars on the market. This Kona is unlike any Hyundai before it. This is a combo multi-function vehicle that is fun to drive. The new Kona Ultimate is powered by a 1.6-liter turbocharged 175 horsepower four-cylinder hooked to a seven-speed dual clutch automatic that feels just alike a manual transmission when starting from a stop. The engine RPM rises up before the car moves, just like driving a manual transmission. The shifts are very smooth and seamless under normal acceleration. That all changes when the accelerator is to the floor; the shifting is firm and precise, the engine revs to the red line and sounds great.
strong>Dear Readers: Some advice about the winter and your vehicle: I
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