AfterMarketNews AfterMarketNews Auto Care Pro AutoCareCareerHub Brake&Frontend BodyShopBusiness Counterman EngineBuilder Fleet Equipment ImportCar Motorcycle & Powersports News Servicio Automotriz Shop Owner Tire Review Tech Shop Tomorrow's Tech Underhood Service Speedville

BMW Recognized for Engine-Building Excellence

BMW Group’s engine-building prowess was recognized with four wins at the latest International Engine of the Year Awards. The drive unit in the BMW i8 earned two class wins as well as being declared overall winner, with a further class win being garnered...

Read more...

Diagnostic Dilemma: The Case of the Missing Code

When doing mobile diagnostic work, no-code stalling complaints are a major part of your agenda. In most cases, the client shop is simply too busy to duplicate the failure or, in some cases, a long test drive will yield nothing in the way of useful...

Read more...

Secondary Ignition: The Art of Spark

What is a coil? From the beginning of the internal combustion engine, several different ignition systems have been used to create a high-energy spark. The most popular system, and the one that’s in use today, is a step-up coil. A coil is nothing...

Read more...

Raybestos Partners With Schwartz Performance To Restore Classic '69 Mustang Fastback

Raybestos has joined forces once again with Schwartz Performance to restore an American icon muscle car: a 1969 Ford Mustang Fastback. “Raybestos and Mustang are the perfect match of history, leadership and innovation. Working with the first-class...

Read more...

Top 10 Brake Job Mistakes For Pads, Rotors And Calipers

Here are the top 10 brake job mistakes made by rookie technicians when replacing brake pads, rotors and calipers.   10. Not cleaning the brake slides and hardware: Just slapping new pads where the old pads once resided never works. The...

Read more...

Snap-on Brightens Up Your Workspace With New Rechargeable Shop Light

Get out of the dark and brighten up your workspace with the new Snap-on ECFBAR300 Rechargeable Shop Light. With an innovative Chip-On-Board LED efficiently delivering more light while maximizing battery power, this powerful shop light is ideal for use...

Read more...

Regulators Launch Investigation Into Jeep Grand Cherokee Brake Defect

Federal regulators are investigating whether the automatic braking systems in some 2014 Jeep Grand Cherokees may be defective after receiving a number of complaints from motorists about a potentially dangerous glitch that caused their vehicles to come...

Read more...

Electronic Proportioning Valve: Doing More With Less Hardware

Anti-lock brake systems (ABS) and the HCU are replacing proportioning, combination and other valves to change the braking forces in the front and rear. This is called Electronic Brake Distribution (EBD) and it can dynamically change the proportioning...

Read more...

NHTSA’s GM Brake Line Corrosion Investigation: Reading Between the Brake Lines

There will be no recalls on some GM vehicles for brake line corrosion. Instead, we received an advisory from the National Highway and Traffic Safety Administration (NHTSA) about brake line inspection and car washes. What was not discussed was the corrosion...

Read more...

Hunter's Social Media Contest Includes Trips to SEMA 2015

Hunter Engineering has launched a new, two-part social media contest that offers trips to SEMA 2015 and the chance to win a free SmartWeight Touch wheel balancer at the show. Before SEMA, two shops can win a trip for two to SEMA 2015 by following Hunter...

Read more...

Ingersoll Rand's 'Real Work Real Play' Sweepstakes With Gas Monkey Garage And NASCAR Rewards A Tool User With The Ultimate Fan Weekend

Ingersoll Rand, the Official Power Tools of NASCAR and a preferred tool provider for Gas Monkey Garage, has announced the “Real Work Real Play” sweepstakes to reward automotive fans who “get it done” with a weekend of fun. Ingersoll Rand is working...

Read more...

Bosch Relaunches Boschdiagnostics.com With Mobile-Responsive Design, New Layout For North America

Bosch has announced the re-launch of boschdiagnostics.com in North America, continuing to update all of its sites to a mobile-responsive, intuitive design. The URL contains three separate sites, featuring DIY diagnostic tools (DIY), professional diagnostic...

Read more...

Home Asian Tech Tip: Hyundai Check Engine Light Diagnostics

Print Print Email Email

As techs, we prefer to deal with the car with a driveability issue attached, as opposed to the light being the only problem, but both scenarios should be approached in the same manner.

Attach your scanner and make note of the codes that are ­recovered as you develop the diagnostic strategy for this job. But don’t be too quick to clear the codes; the next step is to review the freeze-frame data to see what was going on when the code was set. This information will be more helpful with certain codes, but it’s a good habit to get into no matter what the situation.

DRIVEABILITY ISSUES
First, we’ll look at some problems that have driveability complaints attached. The most common of these are misfire codes. If the misfire is obvious, you may be tempted to get to work and start switching coils, checking wires or whatever, looking to diagnose the problem. But before you do, check the codes and see if there isn’t more information available; if nothing else, the P0300 series of codes will identify the cylinder causing the problem.

But there are many other clues that may be available that will help in the diagnostic process. If you have a misfire code along with a system lean code, you should be thinking that the misfire could be a ­result of a manifold or other vacuum leak.

Even with no code, take a look at the data with an eye toward the fuel trim numbers: Do we have a high positive number on long-term trim, indicating that the system has been adding fuel? Or, is it the less common problem of a negative number that would have you looking at a rich condition, where an ­extreme case like an injector sticking open or a fuel pressure regulator leaking in the vacuum line could lead to the misfire?

Another common driveability problem that may or may not have an associated code is a stumble or cutting out on throttle tip in. If the check engine light is lit, hook up your scanner and retrieve the code; the most common will be a system lean code (for more information on engine airflow sensors and engine management systems, click here). While you have the scanner installed, take a couple of minutes to look at the other available parameters. Are the temp sensors reading correctly with a cold engine? The coolant and air temps should be close. Taking a look at the throttle position switch, paying particular ­attention to the off idle area, there have been some ­reports of problems with the switches that become apparent when the connector is “wiggled.” Don’t overlook mechanical concerns; be sure to check the air intake hoses for cracks that will open up when the engine moves with torque.

In the case of “no start” problems, it pays to know the service history. If the car has suffered a broken timing belt, it’s a good possibility that some debris from the broken belt has found its way to the crank sensor, causing damage to both the sensor and trigger wheel. On the 2.4L engines, the balance shaft belts have been known to fail and go unnoticed until the pieces finally take out the crank sensor, resulting in a “poor run” or “no start.”

REAL-WORLD EXAMPLEELANTRA GLS
We recently had a 2002 Elantra GLS in the shop that had assorted problems. Let’s take a look at this job, as it’s a good example of some common problems you might encounter. The car wasn’t in great shape and a persistent check engine light was preventing it from passing state inspection.

As is often the case with this kind of job, the ­customer was reluctant to make a big investment, but wasn’t in the position to buy a new car. The obvious problem was a code for a solid misfire in the number 3 (P0303) cylinder, as well as a code for a slow ­response from the front O2 (P0133) and a system lean code. In addition, there was a slight but audible exhaust leak at the flex pipe before the cat. The customer had ­already installed a new O2 sensor, but the code persisted.
We explained to the customer that there was no way we could give a firm price on the job, but received authorization to get started with the diagnosis and get further authorizations as the job progressed.

The first step was to deal with the misfire. Since we also had the system lean code, we knew the problem was with cylinder 3; we went right to the manifold in that area. A quick shot of intake cleaner at the manifold flange smoothed the engine out, letting us know we were on the right track. To confirm and pinpoint the problem, we used a stethoscope where the sound of the leak was obvious.

Pages: 1 2Next page

Latest articles from our other sites:

Top 10 Fuel Pump Fails

10. Strainer Blocks Fuel-Level Sender A fuel pump inlet strainer may be installed that is interfering with the travel of the fuel-level sensor’s float arm, which causes an optimistic fuel level...More

GMC Yukon No-Cranking Complaint: The 1,300-Mile Test Drive

This month’s Diagnostic Dilemma is about the technical and professional issues involved with attempting to diagnose an extremely random no-cranking complaint on a 2003 GMC Yukon equipped with the 5.3L...More

Mazda Miata Awarded Top Honor by J.D. Power Survey

The third-generation Mazda MX-5 Miata is finishing up its model run on a high note, as it was recently awarded top honors in its segment for J.D. Power’s annual Initial Quality Survey (IQS) for the sixth...More

Ten Vehicles Vying For $5,000 Grand Prize In Champion 'King Of The Road' Contest

It’s time for fans of Federal-Mogul Motorparts’ Champion Spark Plug brand to cast their votes to name the grand-prize winner of the Champion “King of the Road” contest. Enthusiasts can vote for...More

Chrysler Tech Tip: Stability Control System Engages Prematurely

Problem:  ESP system may prematurely activate momentarily when negotiating a curve or MIL illumination due to diagnostic trouble code P0340, P0344 or P0116. Overview: This bulletin involves selectively...More

Honda Tech Tip: Dampers Lock Up After Lowering Vehicle on a Rack

You’ve got your service customer’s vehicle up on a rack to do some work. You lower it back down, but now it looks like a 4x4 ready for some serious off-roading or it feels like it’s got a rock-solid...More

GearWrench Expands 120XP Ratcheting Wrench Line

GearWrench has announced the availability of 11 new open stock combination ratcheting wrenches to its 120XP Universal Spline XL Ratcheting Wrench line. According to the company, 120XP Universal...More

Hunter's Social Media Contest Includes Trips to SEMA 2015

Hunter Engineering has launched a new, two-part social media contest that offers trips to SEMA 2015 and the chance to win a free SmartWeight Touch wheel balancer at the show. Before SEMA, two shops...More