DEAR CAR TALK: My 1997 Mercedes E420 leads a very leisurely life, sitting in the garage for months before being called on for the occasional road trip. Lately, I’ve been experiencing a rough idle condition, where the engine rpm varies between 550 and 700, like a bad engine miss. Acceleration, driving around town or driving on the highway doesn’t create a miss, with the car performing as normal. No “check engine light” has ever appeared, although it does illuminate at startup, so I know it works. When I had an OBD scan, two codes came up. One code is an oxygen sensor, and the other a secondary air-system code. Can you provide any insight about how to get my baby running well again?
— Martin DEAR MARTIN: Well, if I had to take a wild stab at it, I’d say you need an oxygen sensor and some work on your secondary air system. How’s that for clairvoyance?
Actually, even though the scan identified those two problems, they may not be responsible for your rough idle. Of the two, a rough idle is more likely to be related to the secondary air system, which is responsible for maintaining the right fuel-toair mixture when the engine is cold.
But the rough idle could be caused by something else entirely. And because you drive the car so infrequently, it could be that your injectors are just gummed up. That can come from not driving it enough, and having the same tank of gas in there for six to eight years at a time.
So I’d start by trying a fuel-system cleaner. We use a product in the shop called 44K, which is made by BG. But if you can’t find that, try Chevron Techron, which is widely available. Use it for a few tanks of gas in a row and see what happens.
If that helps, then try driving the car more often and not filling the tank before you store it — so you can add fresh gasoline 11 months later, when you fire it up for the Fourth of July parade.
You’ll still have to take care of those emissions codes that came up during the scan if you want to pass your next inspection. And, remember, without an inspection sticker, you won’t be able to drive the car, and your injectors will gum up again. Good luck.
DEAR CAR TALK: I have been an automotive instructor for 24 years, and recently the college I teach at approached me to teach a course on the “history of the automobile in America.” Understand, I’ve always taught the vocational side of cars (auto-body repair) and maintenance courses for beginners, but this course intrigues me. The good news is that the topic is huge, with almost 2 billion sites and pages on the internet. The bad news is that the topic is huge, with almost 2 billion sites and pages on the internet! How would you lecture on a topic this big, covering it in about six to eight talks? By the way, I love your column.
— Russ DEAR RUSS: Great question.
As you might guess, there are 2 billion ways to approach this topic. So I’ll just give you one way you could potentially organize the lectures.
Your first lecture or two could be about automotive technology. Keep in mind that the most interesting stuff happened in the early days of cars and in the past 30 or 40 years. Early on, you had the internal-combustion engine, the production assembly line, hydraulic brakes and the automatic transmission. And then there was a long period of time with very little meaningful innovation.
Then in the past few decades, spurred by the EPA and by higher gasoline prices, computerization and fuel injection have transformed fuel economy, emissions and reliability.
From there you can lecture on safety innovations over the years, which also have been revolutionized by computers. Tucker and Volvo had some early safety advances, which were mostly ignored. Then, in the 1960s, Ralph Nader started complaining about all the people getting killed in cars. That started a push for some amazing safety improvements, from mandatory 3-point seat belts to crumple zones, air bags, ABS, electronic stability control and, most recently, today’s pre-autonomous driving technologies.
Another lecture could be on our most popular cars. You could spend one session on big hits: the Model A, the late’ 50s Chevy sedans, the Mustang, the VW Bug, the Honda Civic, the Toyota Camry. You can try to figure out why (styling? design? competitive advantages?) those cars were so popular — and why some, like the ’60s Mustangs, are still popular, even though they’re horrible cars when compared with even a modern-day Kia Rio.
You also could lecture on big flops, like the Edsel, the Pacer and the Aztek. You could talk about what the manufacturers thought they were improving, and why they turned out to be wrong.
And then your last lecture could be a look to the future, with fully autonomous cars and vehicle-to-vehicle communication to prevent accidents.
And by the way, Russ, if all that autonomous driving stuff works, it could put you auto-body guys out of business. So it’s good you’re branching out into academia.