Dear Car Talk:
I was wondering how much traffic noise comes from engines and how much from tires on pavement? My house is near an urban expressway.
Will our neighborhood get any quieter when all vehicles are electric and there are no internal combustion engines on the road? -- Larry
CAR TALK: Internal combustion engines make the most noise when they’re working hard -- like when they’re accelerating or moving a car up a hill. And they’re not generally working that hard when a car is just cruising down the highway.
If you’re near a flat section of highway, Larry, those cars are in high gear. That means most of their engines are turning at a modest 1,800 to 2,500 rpm. So, the bulk of the noise you’re hearing is tire noise.
You can confirm this yourself. Next time you’re cruising down the highway, turn off Beyonce for a moment and see what you can hear most -- the engine or the wind and road noise. It’ll be the latter.
Sound energy doubles for every 10 mph or so of speed. So road noise from traffic at 70 mph is going to be a lot louder than road noise from 30 mph traffic. As you and your family can attest.
Electric cars are more likely to help with noise on slower and residential streets, where acceleration can make as much noise as tires. And they’ll be particularly helpful in reducing noise when large trucks go electric. That’ll help your situation, Larry. But electric drivetrains, on their own, won’t solve your highway noise problem.
The good news is there are other technologies that may help. Lots of places are using rubberized asphalt to pave roads now. That’s asphalt mixed with bits of old tires. Kind of a homeopathic approach. Tire vs. tire. Those roads are a lot quieter. And there are experimental road surfaces being developed that might reduce noise even more.
And in the meantime, there are noise-canceling headphones.
For phantom car issues, check the ‘pending codes’
Dear Car Talk:
I have a 2004 Saturn Vue with a Honda V-6 engine and 150,000 miles. I bought the car with 54,000 miles on it. I have no significant problems with it except that when going uphill at about 1,700 to 1,900 rpm, there is a slight “stutter” in the engine.
My mechanic, who is a great, honest guy, cannot get the engine to do this despite several test drives. A friend advised me to change the transmission fluid. What do you think? -- Mark
RAY: Changing the transmission fluid is like chicken soup, Mark. It can’t hurt. But I think it’s much more likely you have what we call a “miss.”
Not to be confused with the Saturn Vue, a vehicle that was widely considered to be a “miss” for Saturn. A miss is an engine misfire. It’s most likely to be noticed when the engine is under load, like when you’re climbing a hill. It’s often electrical in nature and usually easy to fix -- once you can find and identify the cause.
Normally, an engine miss will turn on your car’s “check engine” light and store a fault code in the computer. Your mechanic would then use his scan tool to check the code, which will tell him what part has malfunctioned.
But if a problem is intermittent and of short duration, the computer might consider it a phantom event, and not store a code or turn on the check engine light.
In that case, it may store the information as a “pending code.” That’s information about something that went wrong, but it hasn’t happened regularly enough to become a pattern yet. So ask your mechanic to check for pending codes.
Misfires are most often caused by bad spark plugs, bad plug wires or bad ignition coils. Those all are part of what we call the secondary ignition system. And you’ll be glad to know none of that is home equity line of credit level stuff.
If there are no pending codes, you can wait until the problem gets worse, at which point it will turn on your check engine light. Or, if they’re due to be changed anyway -- and, at 150,000 miles they probably are -- you can take a guess and replace the plugs and wires and see what happens. Good luck.
Got a question about cars? Write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.
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