How to get a newfangled car through the car wash

Dear Car Talk:

I have a 2017 Buick LaCrosse that has the gas-saving feature of shutting off the engine at stops and then restarting when the brake is released. It also has an unfortunate feature of putting the transmission into park whenever the start/stop button is pushed to stop the engine; the only way to leave the car in neutral is to leave the engine running. So, how do I manage to get the car through a commercial car wash? Are they familiar with this peculiarity? I asked a salesman at my Buick dealer this question. His response was that the car-wash tracks are wet and, therefore, slippery: "Just leave it in park and let the wheels slide." That is about the dumbest thing I have ever heard. Is there a way to run the car through a car wash without sliding the tires? The only way I can think of is to leave the engine running, and then the transmission can be put into neutral. However, I don't think the car-wash people would like that. – Newton

RAY: The salesman's an idiot, Newton. I mean, I'm an idiot, too, but since this is my column, I'll call him out first.

Putting the car in neutral is exactly what you should do. If your car wash is the most common type, where the driver stays in the car, then you can leave it running, use the foot brake when you come out the other end, then put it back in drive and go. If it’s a car wash that requires you to exit the vehicle, you may have to open the driver’s door first, before putting the car in neutral, to prevent it from shifting into park automatically when you open the door.

Actually, lots of cars are having trouble getting through automatic car washes these days. Car washes haven’t had this much publicity since “The Bikini Carwash Company II” came out in 1993.

It turns out a lot of the new “autonomous driving” safety equipment is not playing well with these car-cleaning tunnels. For instance, a lot of new cars have a wonderful feature called “automatic emergency braking.” If the car senses an object in front of you – like a stopped car or a human dressed as a tuna fish sandwich – and you don’t brake in time, it assumes you’re distracted and it automatically stops itself for you. Now, what do you think it does when it sees a giant spinning buffer heading toward your grille (unless the system disengages itself when the car is put in neutral)?

Other cars automatically apply the parking brake if the car is stopped for more than a few seconds. This also is a great safety improvement. It’s prevented people from stepping out of the car without putting the transmission in park first and running over themselves. Hey, it happens!

So for people like you, with newer cars, you’ll have to check your owner’s manual. More and more of them now have instructions for going through an automatic car wash. It’s more complicated than in the old days, when all you had to do was decline the muffler polish, give the guy your eight bucks and remember to close the window. Now you often have to disable a bunch of safety features, lest you find yourself at the front of the line, unable to go forward through the car wash, with 16 people behind you getting furious while you scan the index of your owner’s manual.

I’m not intimately familiar with the 2017 Buick LaCrosse, but if it’ll stay in neutral with the car running, and it doesn’t have those safety features engaged, you should be fine. Hope you can clean yourself up, Newton.

Performance unlikely to be affected by bad cam sensor

Dear Car Talk:

I have a 1996 Ford Explorer with 164,000 miles. It runs fine, but a year ago, the check engine light came on and indicated a problem with the cam position sensor. The Explorer lives on a very small island with dirt roads and no mechanic. It is driven a maximum of about 40 miles a year, from the marina to our cabin, which we visit once a month or so. After a year with the check engine light on, the Explorer still runs great. Should I worry? – Peter

RAY: No. I'm guessing you retreat to a rustic cabin on a desolate island precisely so you don't have to worry. So don't start now.

The sensor probably is bad, Peter. But the effects of a bad cam position sensor are most likely to be felt at high speed. So just don’t take any dirt highways on the island.

That sensor helps the computer compare the positions of the cam shafts and the crankshaft. And it uses that information to control the timing of the fuel injectors and the spark.

But, like I said, those things become more critical at higher speeds. And if you’re just moseying (and I hope you are) from the marina to your cabin and back, you might never notice any problem at all.

And at worst, if it fails completely, it won’t disable the vehicle; it’ll put it into a so-called limp-home mode – which is what it sounds like. You might not even know the difference! In any case, in the worst-case scenario, you’ll still be able to limp to the cabin.

At that point, you need to befriend a Ford mechanic, and then invite him to spend a peaceful, bucolic weekend on a secluded island. Then tell him to bring a ’96 Explorer cam position sensor with him.

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