Ask the Auto Doctor

Q own crossovers. from : each 2017 the My transmission wife purchased Nissan There’s and Rogue daughter no their noise in my daughter’s my groans wife’s in the Rogue vehicle; lower grunts speed, however, and but no such thing occurs at highway speeds. The dealership service department acknowledges the problem, but the manufacturer doesn’t. Do you have any advice as to Nissan’s CVT transmission? — D.B. A : Yes, some CVT transmissions do emit some strange noises. The dealer is correct; there are no noise fixes for these vehicles. Ask the dealer to check for engine mounts or loose metal shields that could make any metallic sounds. On the plus side, the new CVT transmissions can be manually shifted and you can feel the RPM change under hard acceleration. Q : I installed Pirelli tires on a 2009 Honda Accord. The rating on the sidewall of the tire is 50 psi, but the doorjamb placard says 32 pounds. What would be the correct pressure? When I told my local tire company to put in 50 pounds they said they would go no higher than 38 psi on said tire. What is your recommendation? — David. A : I often get asked this same question. The answer is to go no higher than 5 pounds above what’s cited on the tire placard card — not the maximum psi on the tire sidewall. The only exception is on trucks with load range E tires used for towing or heavy weight; under these conditions using the max air pressure on the tire sidewall is acceptable. After the usage, lower the pressure to the tire placard pressure. Q : on, The sometimes engine light flashes, comes and then my Dodge Dakota pickup truck loses power. The dealer said they have to check while the light is flashing, however, it would not flash during the checkup. Any advice? — Jerry. A : A flashing check engine light in any 1996 and newer vehicle usually indicates an engine misfire. The technician should be able to use a professional grade scan tool and look into the computer memory for history fault codes without the check engine light being illuminated. Q four-cylinder : GMC I purchased Acadia engine with a 2017 and the love everything about it, except the engine auto start/ stop feature, which I finally figured out how to disable. My wife has a 2017 Acadia with the V-6 and on highway cruising it deactivates two cylinders to save fuel. I bought them four months apart and the V-6 actually gets better gas mileage. My four-cylinder engine gets better gas mileage with the auto start off. It loses 0.4 mpg with it constantly starting and stopping. — Dean. A : Some vehicles, such as your General Motors SUVs, do not have a cancel button for the auto start/ stop feature. But, yes, there are some ways to disable it as you have found, though it seems odd that you would see better fuel economy by deactivating it, as this technology is designed to reduce fuel waste while idling (the more you idle, the greater potential for savings). More vehicles will be entering the marketplace with auto start/ stop, and most will have an optional cancel button, or a sport button. As for the vehicles with cylinder deactivation reducing engine cylinders when cruising, there are aftermarket companies that sell performance programmers that plug into the ALDL connector under the dash, and reprogram the engine’s computer settings. The average cost is around $300 to $400. The program can be removed when bringing the car back for warranty service.