Oxygen Sensors Read the Amount of Unburned Oxygen in the Exhaust
The O2 sensors located in the exhaust manifolds provide the essential feedback for the fuel control loop that regulates the air/fuel mixture. On V6, V8 and V10 engines, there is one O2 sensor in each exhaust manifold. On four and straight six engines, there is usually only one O2 sensor in the exhaust manifold.
OBD II Engine Diagnostics: Not as Simple as it Seems
Anybody can plug a scan tool into a vehicle and read codes. But do they know what the codes mean, how to diagnose the fault or, most importantly, how to fix the vehicle? The problem with reading OBD II codes is that the code tells you only that a fault has occurred. It does not
Emissions Update: Understanding How Wide Ratio Air/Fuel (WRAF) Sensors Work
Instead of giving a simple rich/lean indication, wide ratio air/fuel sensors measure the “actual” air/fuel ratio. A WRAF sensor can measure mixtures that range from extremely rich to extremely lean (even straight air!). This ability allows the PCM to control fuel mixtures much more precisely, to handle much leaner fuel mixtures, to reduce emissions and
Catalytic Converter Diagnosis
The catalytic converter is probably the most important emission control device on a vehicle because it cleans up the pollutants in the exhaust. Thanks to fuel injection, oxygen sensors in the exhaust manifolds, and a feedback fuel control system, emissions are kept to a minimum. Even so, some pollution is still produced and must be
The Wheels on the Bus Go Round and Round
Now that school is out, school bus inspections and maintenance is taking place in preparation for the next session in the fall. Many school districts are outsourcing the maintenance of their buses. This could be your chance to increase your shop’s customer base. While the coach work (body) of buses is changing to incorporate features
Oxygen Sensors: Are You Up to Date on the Latest Designs?
If you’re a technician who works on late-model import vehicles and diagnoses engine performance and emissions problems, you probably have a good understanding of how oxygen (O2) sensors work. You know that all late-model engines have at least one or more “upstream” O2 sensors in the exhaust system to monitor the air/fuel mixture, and one
‘Sensing’ Problems: A Drop in Fuel Economy and Higher Exhaust Emissions Signal O2 Sensor Replacement
Oxygen sensors have been used for more than a quarter of a century, dating back to 1980 when the first computerized engine control systems appeared. Part of the fuel management system, the oxygen (O2) sensor monitors unburned oxygen in the exhaust. The powertrain control module (PCM) uses this information to determine if the fuel mixture
You Can Tune a Carburetor, but You Can’t Tuna Fish
I don’t know where the term “master engine tuner” originated, but I suspect it parallels that of “master piano tuner” because both disciplines transform apparent discord into apparent harmony. In this day of electronically managed engines, we forget that mechanically controlled spark advance curves and carburetor mixtures don’t compensate for changes in barometric pressure and
PCV Service: Helping an Engine Catch Its Breath
I’m certain that each and every one of you have, at some time in your life, experienced the horrific event of having the wind knocked out of you. If you can remember back to the first time it ever happened, before you knew that you would, in fact, breathe again, it was like you were
Diagnostic Solutions: Air/Fuel Ratio Sensors
Diagnose and Solve the Root Cause of Sensor Failure Before Sensor Replacement
Cleaning Carbon from TDI Intake Systems
Volkwagen has been selling diesel-powered cars in the U.S. for almost 30 years. Turbocharged versions have been available for 25. That is a lot of experience and a testament to the development of a reliable, efficient and durable powerplant. The introduction and development of the TDI (turbocharged direct injection) brought the VW diesel into the
Hot Tips From Hot Rod Builders
Sometimes the best opportunities are cleverly hidden in plain view. As one example, when Chris Lafferty of Lafferty Engine Creations was asked why he opted to expand beyond race engines into the hot rod and muscle car arenas, he snorted, “Just look outside.” His North Carolina facility sits squarely in the middle of both NASCAR