Gary Goms, Author at UnderhoodService - Page 7 of 25
Winter Starting And Charging System Maintenance

In addition to checking the strength of the antifreeze, a cold-weather starting inspection should also include testing and visually inspecting the battery and cables, starter, alternator and changing to the auto manufacturer’s recommended engine oil. Because cold weather slows down the chemical reaction between its electrolyte and its battery plates, the average battery can lose more than 50% of its cranking amperage at 0 degree F. For that reason, cold-weather starting quickly separates OE-specification from non-OE-specification batteries.

8 Common Diagnostic Mistakes

Many diagnostic mistakes that become “diagnostic dilemmas” are caused by basic oversights or incorrect assumptions on the part of the technician. Research time and testing time have become the cornerstones of modern diagnostics.

PCM Diagnostics Case Study: No-Code Misfire Diagnosis On A 1998 Toyota 4Runner

When doing mobile diagnostic work for other shops, contributing writer Gary Goms usually sees more than his share of random no-code engine performance complaints. In the following case study, the customer of a client shop complained about an intermittent rough idle on his well-maintained 1998 Toyota 4Runner, but only when it was driven in hot weather. The client shop couldn’t duplicate the complaint, no matter how long the engine ran. Of course, the lack of DTCs didn’t help the diagnostic process.

Diagnostic Dilemmas: Solving Starter And Alternator Problems

The starter “solenoid” is actually a combination of an electric relay and solenoid. The relay portion electrically connects the starter armature to the battery. The solenoid portion mechanically engages the starter’s drive pinion with the engine’s flywheel gear.

Building Oil Change Profits One Job At A Time

Gary Goms defends the oil and filter change, but suggests introducing the term, “recommended maintenance interval,” and explains how shops can capitalize on profitable lubrication, drivetrain, filter, lighting, battery and tooling services in the process.

Diagnostic Solutions: Variable Camshaft Timing And Back Pressure Issues

When the topic of variable valve timing (VVT) comes up in import repair shops, few realize that the concept of increasing low- and high-speed engine torque by automatically advancing and retarding valve timing isn’t a recent development. For example, I recently discovered an old variable camshaft timing gear that I bought during the 1960s featuring a torsion spring device that retards valve timing in response to the increased rotating torque needed to turn the camshaft at higher engine speeds.

Diagnostic Dilemmas: Building A Plan For Diagnosing Electrical Problems

Every once in a while, I see the topic of a diagnostic check sheet come up on the International Automotive Technician’s Network (iATN) or other industry media. Most often, the question is asked by a shop owner or service writer who is trying to simplify his life by devising a “canned” step-by-step approach to solving various electronic diagnostic problems. Although a canned procedure is a good place to start, it’s not a sure-fire way to solving electronic problems.

Troubleshooting Mass Air Flow (MAF) Sensors

Troubleshooting mass air flow (MAF) sensor problems can become a major headache for import technicians because the failure is usually one that involves a calibration error rather than an outright electrical or mechanical failure. Because calibration errors tend to be “gray-area” types of problems, we will begin by looking at the basics of how a “hot-wire” MAF sensor measures airflow through an engine running at various speeds and loads.

Diagnostic Solutions: Engine Coolant Temperature Sensors

Considering that roughly 1,500 or more different vehicle models are introduced into our domestic market each year, it’s becoming more difficult to predict how a Powertrain Control Module (PCM) will utilize data from a particular sensor or detect an out-of-range sensor in any single vehicle platform. The engine coolant temperature (ECT) sensor provides a good illustration of how many on-board diagnostic strategies have changed.

Diagnostic Dilemmas: Changes In Our Diagnostic Outlook

Everybody likes to read about a Diagnostic Dilemma that has been solved to everybody’s satisfaction. But this month I have an unsolved Diagnostic Dilemma that is more about customers than cars. This particular dilemma involves a 2005 Ford Crown Victoria with headlamps that randomly lose power during night driving.

Drum Brake Service: Single-Anchor, Floating Shoe Designs

Although four-wheel disc brakes currently dominate the import brake service market, millions of drum brakes are serviced each day in independent import shops. Thanks to their age, many drum brakes present problems related not only to normal wear, but also to extended age and mileage.

Diagnostic Solutions: Extended Oil Change Intervals

Extended oil change intervals are a mixed blessing. On the upside, extended oil change intervals are conserving precious oil and reducing carbon emissions. On the downside, many vehicle owners are forgetting to check their engine’s oil level between oil changes. The most common result is an engine ruined by excess accumulations of varnish and sludge due to using motor oils that are not approved by the engine manufacturer.