Diagnose Driveability Problems by Adjusting Carburetor Jet Screws? Not Anymore

With today’s rapidly advancing automotive technology and electronic controls, it’s more important than ever to match diagnostic skills with today’s world.

To say that repairing cars has changed over the last 30 years is really a gross understatement. In the good old days (let’s say the period of time just before the end of the muscle car era, around 1972, and earlier), diagnosing a driveability problem was as easy as asking when the last time a tune-up was done (for you youngsters who are unfamiliar with the term tune-up, go read a history book). If it was more than 6 months, it was a good bet that the ignition points were worn and/or the dwell angle had to be re-adjusted. End of problem.

Vacuum leaks were easy to diagnose for two reasons: (1) the vacuum hoses were easy to find and (2) you could actually hear the vacuum noise. Dirt was a common enemy to the carburetor (if you don’t know what a carburetor is, see the above paragraph) and it was easy to learn how to disassemble one and clean it. Finally, spark plugs did not last anywhere near 100,000 miles. Installing a new set after 25,000 miles would breathe new life into a car.

Today, the typical passenger vehicle has several computers that control almost every aspect of operation. And, diagnosing a computer-controlled car can be quite a challenge. It requires a whole new set of skills, training and tools. As with many things in our society, efficiency and performance has brought complexity along with it. The perfect example is the TV. HDTV has outstanding color and resolution. Back in the good old days, the picture and sound were OK. If there was a problem, you took a look at the tubes. And you took these suspect tubes to the local drug store, which had a test machine. If the tube was bad, you bought a new tube. End of problem. By contrast, “fixing” an HDTV requires specialized skills and technology. Just like today’s cars and trucks.

Yesterday’s Car vs. Today’s Car

In many ways, today’s passenger car is not that different than the car of yesteryear. The basics of the internal combustion engine, suspension and transmission really are not that different from cars of 30 or 40 years ago. But the major difference is how the engine, suspension and transmission are controlled. In the past the control was done mechanically, or by vacuum. For example, the air/fuel ratio was set by the size of the jet screws in the carburetor. Ignition timing was set by rotating the distributor to a set point and locking it in place. The automatic transmission shifted gears by sensing engine vacuum. Control is not done that way anymore.

Control in now done by computers—and lots of them. Take a look at Figure 1. This wiring schematic is for a very simple device on a 2007 minivan; namely, the front headlamps. The front headlamps are actually wired through a computer! The wiring schematic for a complex system such as the airbags could not fit in the space of this article. What does this all mean? It means that the person that diagnosed problems 40 years ago could not do the job today. It’s a different job that requires new and different skills.

The use of computers has brought with it an unprecedented level of reliability. Some routine maintenance, such as oil changes and wheel alignments, should still be done on a regular basis, but today’s automobile has become turn-the-key-and-drive. When a particular component does fail, it is usually replaced, not rebuilt.

For example, brush replacement in alternators, along with Bendix drive replacement in starters, were common tasks at the corner gas station. Carburetors were often disassembled, cleaned and rebuilt. None of these jobs are done anymore (even fuel injectors are replaced with Mopar® O.E. or Mopar reman units, not rebuilt). So the skills to do these tasks are no longer needed.

Today’s Challenges for the Technician

In the good old days, what do you think were the most important tools in a mechanic’s tool box? The spark plug socket and ratchet? The set of box wrenches? Screwdrivers and pliers? Do you know what the most important tool in a technician’s (we don’t use the term mechanic any longer) tool box is today? It’s a diagnostic scan tool, such as the DRBIII® or equivalent (see Figure 2).

Due to the extensive use of computers in modern vehicles, automotive technicians must have knowledge of how these computers work, how the computers control the different systems, and how to diagnose a problem when it occurs. Technicians, however, still need to understand the basics of how an engine develops power, how the suspension controls the vehicle and how the transmission transmits power. But that knowledge must be supplemented with coursework in electronics to understand the control systems for the engine, suspension and transmission.

Additionally, new systems have been developed that were unheard of a generation ago. These include emission controls, airbags, antilock brakes and navigation systems. Repairing and diagnosing these systems also require new skills.

Training Today’s Automotive Technician

There is a critical shortage of qualified automotive technicians in the U.S. today. “Estimates on the shortage of technicians range from 35,000 to 60,000 per year, depending on the source,” said Richard White, Senior Vice President of Marketing and Member Relations for the Automotive Aftermarket Industry Association. “Every industry is looking for educated, skilled, talented and experienced professionals.”

So if you want to succeed as a skilled automotive technician and diagnostician, where do you start? Many community colleges and vocational schools offer state-of-the-art training programs that reflect the advanced technology of today’s vehicles.

If you’re interested in a Chrysler, Jeep® or Dodge dealership setting, you’ll want to check out Chrysler’s College Automotive Program (CAP)—a two-year automotive service program that leads to an associate degree in automotive technology www.chryslercap.com. But there are a number of other resources that will match diagnostic skills with today’s advanced technology. Universal Technical Institute www.uti.com is a large training program that encompasses automotive, motorcycle, marine and diesel industries.

Opportunities abound in today’s automotive service market. As the vehicle fleet in the U.S. continues to age, more and more vehicle owners take their cars and trucks to independent service and repair shops. Techs at these shops need to be as well trained as dealership technicians. Here are some other resources to consider for those wanting a fulfilling career in the 21st century:

• National Institute for Automotive Service Excellence (ASE): www.asecert.org
• Automotive Youth Educational Systems (AYES): www.ayes.org
• National Automotive Technicians Education Foundation (NATEF): www.natef.org
• Automotive Careers Today (ACT): www.autocareerstoday.org

As we look toward the future, changes in automotive technology will continue to be developed for which technicians will need ongoing training to keep current. The CAN bus system, now being used across the board on all Chrysler vehicles, is the next generation of onboard communications networks. And this system requires the use of the new StarSCAN® scan tool. Other new technology on the horizon that will require additional training and new skills is the hybrid powertrain. For Chrysler, this technology will debut with the 2009 Aspen HEMI® Hybrid and the 2009 Dodge Durango HEMI® Hybrid.

Automotive diagnostics has never been more challenging—or more rewarding—than it is today. Therefore, it’s more important than ever to match diagnostic skills with rapidly advancing technology.