Diagnostic Dilemmas: The Misfire Code As a Symptom
Without question, the 1996 and newer OBD II systems have greatly simplified the diagnostic process. Veteran mechanics well remember the technical loopholes that riddled the old proprietary OBD I systems. All too often, the complex diagnostic charts supplied by the auto manufacturers were time-consuming, erroneous and often concluded with the infamous “replace with component of
Diagnostic Solutions: Oxygen Sensor Diagnostics
Once considered leading-edge technology, today’s oxygen sensor has become a commonplace service item on modern vehicles. Popularly introduced in the 1970s, the Lambda or, as it’s more popularly known, the oxygen sensor, rapidly became standard equipment as it’s a vital component of closed-loop or feedback fuel control technology. By using a voltage input from the
Diagnostic Dilemmas: The Pressures of Intake Manifold Vacuum Tests
Several years ago, a retired school teacher brought in a 1994 Chevrolet S-10 Blazer that had developed an intermittent rough idle condition. Although a rebuilt engine had been installed a year before, and all of the wiring and vacuum hoses looked as if they were in factory condition, I took nothing for granted. An ignition
Diagnostic Solutions: Throttle Position Sensors
Although conventional throttle position sensors attached to the throttle shaft are considered basic technology on modern engine management systems, the conventional throttle sensor plays an important role in its relationship with other sensors. The voltage inputs of most throttle position (TP) sensors may, for example, be coordinated with the barometric pressure (BARO), manifold absolute pressure
Fundamentals of Electrical System Diagnosis
Electrical principles, like voltage, amperage and resistance, can be described as cars passing along the roadway. Voltage would be the vehicle’s speed, amperage would be the number of vehicles on the road at the same time, and resistance would be the potholes in the road’s surface. Basically, electricity is a supply of atoms with an
Servicing Maintenance-Friendly VW Engines
Volkswagens have always been maintenance friendly. From the very first models, ease of repair and durability have been built into the design. VW has managed to keep basic maintenance procedures relatively uncomplicated throughout the years. In this article, I’ll cover some of the more common underhood procedures on common VW models and include some tips
Ignition Misfires
A flashing Check Engine light and a P0301 to P0312 diagnostic trouble code is a sure-fire indication that one or more cylinders are misfiring. Occasional misfires may pass unnoticed, but a steady misfire is hard to miss. The engine usually feels rough, lacks power and uses more gas than usual. Sometimes a misfire may feel
Nissan: Driveability Issues
Earning Loyal Customers Through Accurate and Efficient Diagnostics This article will take a look at some of the common problems that cause check engine lights to illuminate and/or driveability problems on the popular Nissan line of vehicles. With many states adopting statewide OBD II emission inspections, the days of ignoring the light are over. We’ll
Diagnostic Solutions: Reading Spark Plugs Is As Much An Art As It Is A Science
Barring mechanical contact between the spark plug and piston, just about any randomly selected spark plug will ignite the gasoline and air compressed into an engine’s combustion chamber. Very few spark plugs, however, will continue to perform well under a wide range of engine temperatures, loads and speeds, not to mention lasting well beyond today’s
Diagnostic Dilemmas: Internal Engine Diagnostics
The nuts and bolts of measuring cylinder leakage In OBD II diagnostics, most of us know that an external component like a faulty fuel injector, ignition coil, spark plug or spark plug wire is usually responsible for a P0300-series cylinder misfire trouble code. Nevertheless, even with more sophisticated onboard diagnostic strategies, the PCM usually can’t
Diagnostic Dilemmas: Fuel System Foul Ups
Are the fuel pump returns from your shop going up? Understanding the root cause of technician errors is the first step to successfully managing fuel system parts purchases and returns. Over the years, vehicle fuel systems have become more complex as OEs look to improve fuel burning and engine efficiency. And during that time, industry
Scan Tools: Tune In, Tune Up, Cash In
What is with all the new interest in music? Everywhere in the car industry and the aftermarket, people are talking about the “tuner” market. Are they talking about the old stereo of Dad’s in the den? Maybe they are talking about the newest disk player that can support mpeg and iPod? No! The interest is