Diagnostic Dilemmas: Symptom Diagnosis…The Journey Begins
When I first began my automotive career way back in 1957, the symptoms of an ailing engine were very apparent. A carburetor with a worn accelerator pump, for example, would characteristically stumble on acceleration and a closed-up set of distributor contact points would cause the engine to become very sluggish. Low fuel pressure caused by
Diagnostic Solutions: Fuel System Pressure & Volume Checks
For maximum efficiency, modern import fuel injection systems require that fuel be delivered at a specified volume and pressure. Because the fuel injector’s job is to mix fuel with the intake air charge, it must produce a finely misted, conical spray pattern through the fuel injector nozzle. Lower-than-specified fuel pressures not only fail to provide
Diagnostic Solutions: Cooling Fan Failure Diagnosis
Cooling fan operation is often taken for granted by many technicians because testing a cooling fan requires at least 15 minutes of fast idling or running until the coolant temperature reaches 220-230° F. If the cooling fan doesn’t activate, a coolant temperature sensor, fan relay, fan electrical circuit or the fan itself may be at
Diagnostic Dilemmas
It’s Mechanical, Stupid! Just about every student of politics remembers President Bill Clinton’s famous campaign slogan, “It’s the economy, stupid!” Allow me to paraphrase by saying, “It’s mechanical, stupid!” Yes, that’s right, mechanical failures can cause diagnostic trouble codes and, all too often, we tread the Primrose Path because we become lost in a maze
Diagnostic Solutions: Catalytic Converters
The design and function of catalytic converters has changed dramatically since their introduction in 1975. The first “two-way” catalytic converters were oxidizing-only designs that combined hydrocarbon (HC) and carbon monoxide (CO) with oxygen to form water vapor (H2O) and carbon dioxide (CO2). Oxidizing converters were originally manufactured in pellet bed or monolithic “honeycomb” styles. Currently,
Diagnostic Solutions: Springs and Things
Maximizing Ride Control…Steering Response & Handling
Diagnostic Dilemmas: Getting In-Sync with a Couple Wranglers
It’s axiomatic in the diagnostic trade that, as soon as one thinks he has command of a particular system, the gods of technology pitch a curve ball that unerringly slips under the swing of the diagnostic bat. Not that I’ve never seen a 4.0L Jeep engine before; I’ve serviced dozens, perhaps hundreds of them. The
Diagnostic Solutions: A Little Homework Goes a Long Way….
In Diagnosing Intermittent or Hard Starter Failures
Tech Talk: Positioning Yourself to Handle TP Service
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
Diagnostic Solutions: Oil Filters… Are Working Harder Than Ever to Supply Clean Oil to Vital Engine Parts
Although oil filtration isn’t a new science, it’s important to remember that modern engine technology is placing new demands on oil filters. At the very least, modern engines require extremely clean oil for maximum reliability and longevity. But, more important, the use of synthetic lubricants and on-board monitored oil change intervals has allowed manufacturers to
TechTravel: A Speedweek Racing Diary
Jim Linder “Fuel Injector Guru” needs no introduction to the readers of Underhood Service. His reputation as a technical writer and as a provider of quality technical training and electronic fuel injection service extends industry-wide. By now, many of Linder’s fans know that his record attempt was rained out by the third day of qualifying
Diagnostic Solutions: Steering Gears
Keeping Your Customers’ Vehicles on The Straight & Narrow Modern automotive steering gears evolved from the quaint tiller-controlled steering systems used in the first automobiles to the hydraulically controlled systems now used in most import vehicles. Unfortunately, steering tillers that attached to axles with little or no steering geometry didn’t provide much steering feedback from