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Q: I will be driving in Utah, Nevada and the valleys of eastern California, where temperatures above 110 degrees are not uncommon. If I start the day at the recommended max tire pressure listed on the door placard, do I have anything to worry about, or should I bleed the tires, and how much? Also, a pretty good pressure gauge always gives a reading 1 or 2 pounds less than the built-in tire pressure sensors. Which is likely to be more accurate?

F.S., Oak Park, Ill.

A: Never, ever, bleed air from your tires. Although the tire pressure may increase a bit while driving, it will be much too low the next time you start out. Inflate the tires to the pressure stated on the door placard and leave it there. The tire pressure sensors are very accurate. Manual tire gauges, not so much, but close enough. Incidentally, some folks mistakenly think that the maximum pressure figure molded into the tire sidewall is the inflation pressure — it is not!

Q: The manager where we bought our 2016 Ford Fusion hybrid mentioned that Ford is thinking of dropping support for their navigation systems in their vehicles since so many people have a similar system on their smartphones. This idea seems ridiculous since using your phone while you drive is less safe than using your vehicle's navigation system, though Ford seems to be coming up with more than its fair share of bonehead ideas recently. Any truth to this rumor?

M.B., Plainfield, Ill.

A: According to the Ford website: "On August 1, 2018, the SYNC Services subscription service, along with the SYNC Destinations mobile app, was discontinued for 2008 through 2016 Model Year vehicles equipped with SYNC, SYNC with MyFord, SYNC with MyFord Touch, or SYNC with Voice-Activated Navigation. If you subscribed to this feature, you can still take advantage of the many features available through your version of SYNC. SYNC Services relied on technology that is no longer being supported. While this technology was useful when the feature launched, it is no longer the best way to support owner needs. We will continue to focus efforts on new technologies, such as FordPass SmartLink." Talk to your dealer or go online to switch to the new technology.

Q: I've got a 2008 Honda Pilot with about 150,000 miles. Intermittently when stopped at a traffic light, I'll hear a dull "thump" coming from the rear of the car. It's loud enough to make me look up in my rearview mirror to see if anything hit me. It only seems to happen when the car is stationary, but in gear, with the brake pedal depressed. I have never heard it when the car is moving, and it doesn't seem to be related to me depressing or removing my foot from the brake pedal. My Honda dealer kept the car for a day, but couldn't re-create the thumping. Techs checked the car over, including the brakes, and found no issues. Any suggestions?

T.K., Barrington, Ill.

A: Something is moving and hitting something else. Sure, that sounds simple, but so is the solution. We have a hunch that it's the exhaust system. At idle, the car has low-frequency vibrations, especially while in gear. There may be a loose hanger or a break somewhere in the plumbing.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician.