Q: I've watched the automotive marketplace from the sidelines and have noticed that many manufacturers are going to the continuously variable transmission, or CVT, as their transmissions of choice. In fact, it seems that most manufacturers have stopped offering manual transmissions entirely.
I live in western Pennsylvania, where we have a lot of hills and get moderate amounts of snow and ice each winter. I've driven manual transmission cars and SUVs for over 35 years and like the control they offer in these conditions. I am concerned that a vehicle with a CVT might leave me, as they say, high and dry, or _ more likely _ stuck, cold and wet. What is your experience in situations like this? Thanks for your assistance.
_Doug R.
A: I confess to not having any personal experience with a CVT-equipped vehicle in snow, so I did a bunch of checking around in hopes of best answering your question.
CVTs have largely replaced manual and automatic transmissions on many new vehicles, limiting traditional choices. CVTs provide a seamless, shift-free application of torque by using two variable diameter pulleys and a steel belt. CVTs are lighter, simpler and more reliable than traditional transmissions and enhance fuel economy by a measurable amount. It does, though, take a little getting used to the almost continual drone of the engine when in automatic mode.
Most folks seem more than satisfied with how their CVT-equipped rides perform in snowy conditions, particularly with vehicles that include easy-to-use manual "shifting" controls. Subaru's X-Mode is a great example of how a vehicle can add slippery road countermeasures that reduce accelerator sensitivity, bring the CVT, anti-lock braking system, and stability control up on their collective toes, and provide descent control at lower vehicle speeds.
Q: I just purchased a 2002 GMC pickup. When I start the engine on a cold morning, I hear a knocking sound that lasts for about 15 seconds before fading away. What is this? Is it harmful? Did I get snookered?
_Eric P.
A: I believe you're hearing piston slap, which is a fairly harmless condition caused by excessive piston clearance in one or more cylinders. The noise is caused by the pistons wobbling or striking the cylinder walls until they warm up and expand. Common to many GM truck engines of this vintage, this is caused by a short piston skirt design, rings pushed as high as can be on the pistons to reduce emissions, normal wear, and perhaps not the sweetest piston-cylinder fit when built.
While the noise is disconcerting and potentially lowers resale value, it really is harmless. If the noise lasted just a second or two, it could be bearing rattle, a much more serious issue.
Q: My vehicle recently produced a misfire code relating to cylinder 1, and I've been thinking about replacing the spark plugs to see if that fixes the issue. Which cylinder is this on the engine?
_Paul K.
A: Cylinder 1 is the furthest forward (pulley end) on both an inline and a V-shaped engine. On V-engines, if you look closely, the cylinder banks are slightly staggered so the connecting rods of opposite cylinders can attach to the crankshaft. Other V-engine cylinder numberings depend on layout (as in, 12}56 or 135/246). If your engine is equipped with a coil-on-plug ignition system, swapping coils is a neat way to isolate a bad one.
