Acura’s engine light stays on

Dear Doctor: I purchased a 2004 Acura MDX with the 3.5-liter V-6 engine from its original owner. The vehicle has 177,000 miles and runs great. The engine light comes on indicating an emissions problem. The previous owner had the catalytic converter and gas cap changed. He told me the light comes on because of the gas cap. Sometimes I unscrew the gas cap and put it back on and the light goes out. But it does eventually comes back on. What should I do?

— Andy

Dear Andy: Whenever the check engine or service engine light comes on a fault code will also be set. Technicians use a professional scan tool — not just a code reader — and can review all systems from the moment the computer activated the engine light. This is called freeze-frame mode. I have seen a lot of V-6 Honda engines set misfire codes for tight engine valves that need to be adjusted.

Dear Doctor: I bought a used 2015 Nissan Altima with the 2.5-liter four-cylinder engine with 17,000 miles. I’m only getting 17 mpg in city driving, but the owner’s manual says this car should get 27 mpg in the city. The dealer checked the car and said everything is fine. What is going on?

— Forrest

Dear Forrest: To achieve the 27 mpg city rating you would need perfect driving habits and conditions. I would expect low 20’s in the city and maybe 35 mpg highway on a midsize four-cylinder vehicle like yours. I know the advertised mileage is 26 to 27 mpg city and up to 39 mpg highway. You can have the dealer check to make sure the odometer is correct and that the oxygen sensor is working as designed. Also, make sure your tire pressure is set at the recommended setting.

Dear Doctor: I have a 2016 Ford F-150 pickup with 2,000 miles. When can I change over to Mobil One oil?

— Ben

Dear Ben: Some vehicles come from the factory with full-synthetic oil. Today’s engines are much improved over older engines, so too, are the oils manufactured today. At 3,000 miles it is safe to switch over to full-synthetic oil in any engine.

Dear Doctor: With most new cars using synthetic oil does the 3,000-mile or three-month rule still apply to changing synthetic oil as it did in the old days with regular standard oil? It seems to me that changing oil with greater frequency is throwing money away since the synthetic oil is designed to last longer.

— Vinnie

Dear Vinnie: The new regular-based petroleum oil is much improved and comes in multiple viscosity offerings. Synthetic oil also comes in many forms, additive packages and qualities. The full-synthetic oil mileage change intervals range from 6,000 to 10,000-plus miles, depending on the vehicle manufacturer. You must make sure the oil being used in your vehicle meets the manufacturer requirements. Using the wrong oil will cause engine damage.

Dear Doctor: I had both front wheel bearings serviced for “clunking and growling” sounds on my 1996 Mazda B4000 4×4 pickup truck. I’ve had these front wheel bearings serviced nine times. The mechanic said the Mazda B4000 series trucks are known to have wheel bearing issues. Also, the front and rear suspension is very noisy. The mechanic said the bushings for my suspension are pretty much shot due to age. I was told to spray a can of silicone at the front and rear bushings, stabilizer bar, and leaf springs to quiet them down. Finally, the back of my truck is leaning a bit to the left. I got a tape measure and measured from the top of the extended wheel hubcap to the bottom of the wheel well and did the same for the right side and found a 1-inch difference. I had all 4 shocks replaced in December. What do you think? Charles

Dear Charles: There are a few possibilities causing a wheel bearing to wear prematurely. Make sure the wheel bearings are correct and the correct grease must also be packed onto the new bearings. Rear suspension bushings will make more noise during the colder months. Yes, the use of any spray lubrication will quiet down the dried out suspension bushings. As for the 1-inch difference in ride height, check the front height to see if there is also a difference. Check all tires to make sure they are all the same size. If there is a difference on the front height, then correct the front first, as it’s the easiest to do, The rear (if it has leaf springs) would be expensive. The new shocks will not affect ride height, unless they are the spring-over-load type.

— Junior Damato, Motor Matters

Copyright, Motor Matters, 2017

(Manufacturer photo: 2004 Acura MDX)

Junior Damato is an ASE-certified Master Technician.

E-mail questions for publication to info@motormatters.biz

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