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Lambda, Lambda, Lamba: Understanding Oxygen Sensors
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By Counterman
Customers are the core of our business, and communicating with them effectively is critical to our success.
While each customer (and transaction) presents a unique set of opportunities and challenges, individual customers often can be classified into one of several broad types. Obviously, “profiling” or “stereotyping” an individual customer when you first meet them shortchanges everyone involved, but understanding the kinds of customers that make up your clientele gives us an idea of how to deal with each customer type once we actually get to know them.
Depending on which marketing firm or consulting group you choose to believe, there are between four and 10 basic customer types. No matter how many categories you prefer to use, it’s the psychology behind these differences that holds the key to connecting with as many of them as possible. You only get one chance to make a first impression, so a “new” customer is the one with the greatest potential. Even if a new customer has familiarity with your business, they may not have experienced it directly. Your advertising, reputation or a personal referral (presumably all positive) have encouraged them to visit your location for their needs. Now is the time to show them what they’ve been missing!
Consultative selling is a technique that focuses on building a relationship and determining what your products can do for your customer. By concentrating on the customer’s needs, you can further qualify them as one of the many customer types, and then offer the most appropriate solution for their individual situation. The immediate need might be for a battery or brake pads, but discovering the reason behind the intended purchase can open up the conversation in ways that make it easier for you to sell the most appropriate product for your customer. It also can minimize disappointment and build trust, by ensuring that the products and services are truly useful and meet the customer’s expectations.
Once the new customer becomes an “active” customer, you haven’t entirely sealed the deal. There’s a huge difference between gaining a customer and keeping a customer. An active customer isn’t necessarily a loyal customer, so using what you’ve already learned about their needs makes it a little easier to meet those needs each time. Neglecting or disappointing your new and active customers leaves the door open for them to become someone else’s new and active customers. Building upon each successful transaction (and learning from any less-than-successful ones) helps you turn these types of customers into the most desirable customer type: the loyal customer.
Loyal customers are at the heart of the 80/20 rule, which states that 80% of your business comes from roughly 20% of your customer base. New and active customers may come and go (sometimes through no fault of your own), but that solid core of loyal customers is what really keeps your lights turned on and your employees paid every week. As 80% of your business, these are the customers you really need to know and understand. Delivering best-in-class service and focusing on being an integral part of their success will help ensure that these customers remain loyal and even advocate for your business!
With proper care and feeding, we can reap the benefits of that natural progression from “new” to “active” to “loyal,” but along the way we may discover that we have some lapsed or unhappy customers. Timing is critical when addressing these “at-risk” customer types. An unhappy customer (even a loyal one) is likely to become a lapsed customer if we continue to fail them, especially if our competition surpasses us in service, pricing or any other metric. We need to identify and correct the core issues behind their dissatisfaction before that customer has the chance to cozy up to another vendor.
The at-risk customer tends to taper off slowly, so if you aren’t paying attention, you may not even realize it until it’s too late! If a valued customer does become lapsed, you should still attempt to salvage that relationship by determining what caused the lapse in the first place. The feedback also may prove to be useful in the future when dealing with other customers, who might have similar needs and objections.
No matter if it’s a retail or a commercial account, knowing the most effective ways to connect with each customer type helps create repeat business and build your brand.
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By Counterman
While it might not sound like it to the untrained ear, the orchestration of components to achieve the ideal combustion cycle is nothing short of a symphony.
For fuel-injected engines, two important instruments in this precise arrangement are the mass airflow (MAF) sensor and the manifold absolute-pressure (MAP) sensor.
The MAF sensor, typically situated between the air-filter housing and the intake manifold, might be considered the maestro. Also known as an air meter, the MAF sensor uses a heated element to measure the amount of air by weight that’s entering the engine. As the air cools the heated element, this cooling effect changes the electrical resistance of the element. The amount of cooling the element experiences is directly proportional to airflow, and the sensor conveys this information to the engine computer by way of changing voltages or digital frequencies.
The engine computer then uses this information – along with other inputs – to adjust the amount of air entering the engine.
Other inputs that help determine the proper air-fuel ratio include: oxygen sensors, which measure the amount of air in the exhaust gases; throttle-position sensors, which tell the computer if the throttle is closed, partially open or wide open; knock sensors, which monitor for signs of engine knocking; and (on some vehicles) MAP sensors, which measure the amount of pressure or vacuum in the intake manifold.
While most fuel-injected engines today utilize a MAF sensor to obtain a precise measurement of airflow, MAP sensors play a starring role in fuel-injected vehicles with speed-density engine-management systems. However, turbocharged engines often have both a MAF and a MAP sensor.
“In turbocharged engines, the partnership between MAP and MAF sensors isn’t just a technicality – it’s the secret behind the vehicle’s ability to harness forced induction with unparalleled precision,” Walker Products explains.
Let’s take a closer look at each type of sensor and what they bring to the table.
MAF Sensors
Air changes its density based on temperature and pressure. In automotive applications, air density varies with the ambient temperature, humidity, altitude and the use of forced induction (turbochargers and superchargers). Compensating for changes in air density due to these factors is essential for maintaining the optimal air-fuel mixture and efficient engine operation.
Consequently, MAF sensors are better-suited than volumetric-flow sensors to provide an accurate measurement of what the engine needs. MAF sensors offer a more direct and accurate measurement of the critical parameter for engine combustion: the mass of air. This facilitates better engine performance, fuel efficiency and emissions control compared to relying solely on volumetric-flow measurements.
There are two types of MAF sensors used in automotive engines: the vane-meter sensor and the hot-wire sensor.
The vane-type MAF was the first one out there, and it was used on import vehicles from the 1970s and 1980s.
“It didn’t have many actual problems,” Charles Dumont explains
link hidden, please login to view. “However, many of them were replaced, because back then the vehicles didn’t have onboard diagnostic capabilities. Usually after mechanics and DIYers had replaced all the other ignition parts and sensors, the MAF sensor was the last-ditch effort.” These days, you’re more likely to encounter the hot-wire style of MAF sensor. The hot-wire MAF sensor is smaller, faster and more accurate than the older vane-type MAF sensor, making it the preferred choice in most late-model vehicles.
Delphi provides a great explanation of the hot-wire MAF sensor
link hidden, please login to view. “Put simply, a MAF has two sensing wires,” Delphi explains. “One is heated by an electrical current, the other is not. As air flows across the heated wire, it cools down. When the temperature difference between the two sensing wires changes, the MAF sensor automatically increases or decreases the current to the heated wire to compensate. The current is then changed to a frequency or a voltage that is sent to the ECU and interpreted as air flow. The quantity of air entering the engine is adjusted accordingly.”
MAF sensors are pretty dependable, but there are a few things that can undermine their performance.
Any air or vacuum leaks downstream of the sensor can allow “unmetered” air to enter the engine. This includes loose fittings or clamps in the plumbing between the air-filter housing and throttle, as well as any vacuum leaks at the throttle body, intake manifold or vacuum-hose connections to the engine.
Anything that contaminates the surface of the sensor also can hinder its ability to respond quickly and accurately to changes in airflow. This includes fuel varnish and dirt deposits as well as any debris that might get past or flake off the air filter itself.
A frequent cause of MAF-sensor failure is directly related to the air filter. Low-quality or incorrectly installed air filters can allow paper particles or dirt to accumulate on the hot wire, effectively insulating it and affecting the reading of the sensor.
Oil-soaked air filters also can have an effect on MAF-sensor operation, so it’s important to warn someone of this possibility if they’re installing a performance high-flow filter. In some cases, modified intake systems can cause increased air turbulence, which can affect the performance of the MAF sensor as well.
A dirty MAF sensor can cause performance problems and, in some cases, trigger a diagnostic trouble code. You can recommend MAF-specific cleaners (any harsher solvents can ruin the sensor) and air filters as maintenance items before your customer spends the money on a replacement sensor.
Symptoms of a failing MAF sensor could include rough idling or stalling; RPM fluctuations without driver input; and a decline in fuel economy and engine performance. A problem with the MAF sensor often triggers a “Check Engine” light.
MAP Sensors
As the name implies, the primary function of a manifold absolute-pressure sensor is to measure the pressure within the intake manifold of an engine (usually a fuel-injected engine). Essentially, a MAP sensor is measuring the barometric pressure – the atmospheric pressure that’s pressing down on earth. Barometric pressure is influenced by changes in elevation, air density and temperature.
The pressure reading from a MAP sensor is an indicator of engine load, and it helps the engine computer calculate fuel injection for the optimal air-fuel mixture. The MAP sensor helps the engine adapt to different operating conditions, such as changes in altitude or driving up a steep incline, where air pressure can vary significantly.
A MAP sensor contains a sealed chamber that uses a flexible silicon chip to divide the sensor vacuum from the intake-manifold vacuum. As soon as the driver starts the vehicle, the MAP sensor is called into action, performing “double duty as a barometric-pressure sensor,” according to Delphi. With the key turned on but prior to the engine starting, there’s no vacuum in the engine applied to the MAP sensor, so its signal to the engine computer “becomes a baro reading helpful in determining air density.”
“When you start the engine, pressure in the intake manifold decreases, creating a vacuum that is applied to the MAP sensor,” Delphi explains on its website. “When you press on the gas accelerator pedal, the pressure in the intake manifold increases, resulting in less vacuum. The differences in pressure will flex the chip upward into the sealed chamber, causing a resistance change to the voltage, which in turn tells the ECU to inject more fuel into the engine. When the accelerator pedal is released, the pressure in the intake manifold decreases, flexing the clip back to its idle state.”
Typically, you’ll find the MAP sensor in the air cleaner, fender wall, firewall, intake manifold or under the dash, Standard Motor Products (SMP)
link hidden, please login to view. Given their location, MAP sensors commonly fail “due to the constant contact of the movable wiper arm over the sensor element and the exposure to the high underhood heat,” according to SMP. The high heat can melt or crack the electrical connectors. MAP sensors also are susceptible to contamination.
“If the MAP sensor uses a hose, the hose can become clogged or leak and unable to read pressure changes,” Delphi explains. “In some cases, extreme vibrations from driving can loosen its connections and cause external damage.”
A failing MAP sensor will compromise the engine’s ability to maintain the proper air-fuel ratio, leading to a number of potential symptoms. These symptoms could include noticeably poor fuel economy, sluggish acceleration and an odor of gasoline (signs of a rich air-fuel ratio); surging, stalling, hesitating, overheating and a general reduction in engine power (signs of a lean air-fuel ratio); higher emissions that can lead to a failed emissions test; erratic or unusually high idle; and hard starting or even a no-start condition. A faulty MAP sensor also can set off a “Check Engine” light.
Parting Thoughts
MAF and MAP sensors are small components that play a big role in modern fuel-injected engines. With turbocharged engines becoming more and more prevalent in some of the most popular models on the road today, these sensors should continue to play an important role in automakers’ fuel-economy and emissions-control strategies.
“As turbocharged technology evolves, understanding and optimizing the cooperative function of these sensors becomes the key to unlocking the full potential of modern turbocharged engines,” Walker Products explains.
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By Counterman
Wheel-speed sensors aren’t new to any of us. They’ve been around for years, and their initial purpose was to provide wheel-speed data to the control unit for the antilock braking system (ABS). Because of this, they’re often called ABS sensors.
On today’s vehicles, however, the ABS isn’t the only system that utilizes wheel-speed data. Multiple safety and comfort systems such as advanced driver-assistance systems (ADAS), traction control and parallel-parking assist rely on wheel-speed data to function properly.
At a glance, all wheel-speed sensors may appear to be the same. But there are two different types: passive and active. Essentially, both have the same job of providing wheel-speed data to various control units, but they differ in how they do it and how well they do it.
Passive Wheel-Speed Sensors
Passive wheel-speed sensors are constructed with a permanent magnet and fine copper wire and generate a magnetic field. They operate in conjunction with a toothed metal ring, called a tone ring, which rotates at wheel speed. As the teeth of the tone ring pass through the magnetic field, it causes the polarity of the sensor to change and generates an alternating-current (AC) signal.
This AC signal is sent to the ABS control unit, which in turn must interpret it to determine when ABS operation is required. While passive sensors have been effective for many years, they have several drawbacks. A common problem with these and any type of permanent magnet sensor is limited operation at low speeds. In the case of wheel speed, a passive sensor is only able to generate a signal at approximately four miles per hour and higher.
They also do not generate a signal in reverse, and the gap between the sensor and the teeth on the tone ring is critical. Even the slightest amount of rust buildup underneath one of these sensors can cause erratic operation and unwanted activation of the ABS under braking. In addition, the magnetic field of these sensors can attract fine metal particles over time, which further inhibit proper system operation.
Active Wheel-Speed Sensors
The AC signal generated by a passive wheel-speed sensor is an analog wave, or a continuous smooth waveform. An active wheel-speed sensor, on the other hand, produces a digital signal, which is viewed as a square waveform. A digital signal is a very accurate and precise on/off signal.
Many of the other control units associated with today’s advanced systems rely on this type of precision for proper system operation. In addition to the accuracy, an active wheel-speed sensor can read wheel speed practically to zero mph, which is critical data for modern traction-control and driver-assistance systems, and some also can detect reverse wheel rotation.
Active wheel-speed sensors require power to operate, whereas passive units do not. There are two types of active wheel-speed sensors: a Hall-effect sensor and a magneto-resistive sensor. A Hall-effect sensor requires either a toothed or magnetic ring to generate a voltage signal, whereas a magneto-resistive sensor utilizes a slightly different type of encoder ring, allowing it to determine direction of wheel rotation.
The most important part about these sensors is knowing that they’re different. Visually they look the same, but functionally they’re not interchangeable. Some makes and models that are traditionally thought of as the “same” vehicle with different badging can utilize different sensors, even for the same model year.
When it’s all said and done, active wheel-speed sensors are necessary for today’s advanced systems, but regardless, all wheel-speed sensors take a lot of abuse, simply due to their location. Any time there’s a problem indicating a bad wheel-speed sensor, all components must be taken into account including the sensor itself, as well as the wheel bearing and CV joint, which may house or support the tone ring or encoder wheel necessary for sensor operation.
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By Counterman
Continental has added eight new part numbers to its line of OEM knock sensors.
The sensors are the same part that the vehicle manufacturer uses and deliver the exact fit, form and function as the original part, ensuring an easy installation and long service life, according to Continental.
The eight new part numbers provide application coverage for some of the most popular domestic, European and Asian makes and models on the road today. The expanded line covers Chrysler, Dodge, Ford, Infiniti, Jeep, Lincoln, Mercedes-Benz, Mercury, Nissan and Ram models ranging from 2000 to 2023. The new sensors provide coverage for 28.8 million vehicles in operation (VIO) in the United States and 2.4 million vehicles in Canada.
“Our newly expanded line was developed to meet the growing need for reliable knock sensors on some of the most common vehicles on the road today,” noted Brendan Bachant, Continental product manager for engine management and fuel. “The original sensors can be prone to failure due to mechanical damage, excessive vibration, high engine temperatures, and corrosion. Continental has made these OEM sensors available to the aftermarket so that professional technicians can easily and confidently service the most common vehicles in the shop, like the Ford F-150 and Explorer, the Jeep Wrangler and the Nissan Maxima and Altima. Technicians can be confident when choosing the Continental knock sensor that they will avoid comebacks.”
Knock sensors are designed to detect engine ping caused by pre-ignition and relay the information to the electronic control unit to adjust engine timing and help keep the engine running smoothly. These sensors are an ideal repair for a rough-running engine with a timing and knock-sensor fault code and will help shops to restore the performance of their customers’ vehicles to OE specifications, according to Continental.
Continental knock sensors are built in ISO-certified facilities to deliver the highest level of dependability, the company noted.
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By Counterman
Fuel injection is as old as the internal combustion engine itself. However, many of the early systems proved to be somewhat troublesome and quirky. The carburetor, by comparison, was simple and dependable, and therefore the fuel system of choice for the majority of mass-produced vehicles through most of the 20th century.
For those who entered the automotive industry during the reign of the carburetor, fuel injection was so uncommon that as it began to make a comeback during the 1980s, it was largely misunderstood and tagged with the less-than-endearing term of “fuel infection.”
With the help of electronics and computer control, fuel-injection systems began to improve quickly and followed a course of evolution that introduced many different system designs. Suddenly, we were bombarded with unusual terms and acronyms like Jetronic, Motronic, TBI, MFI, GDI, TDI and many more. While it might have seemed confusing at first with so many different coined terms from so many different manufacturers, ultimately there are only two basic types of fuel injection.
Why Fuel Injection?
For efficient combustion to occur, fuel must be atomized first (broken up into the smallest particles possible) so it can mix with the air and vaporize. Only then will it properly burn inside the cylinder.
The job of a carburetor was simply to allow the air flowing through it to atomize the fuel as it draws it out of the various circuits. Carburetors work very well at doing this, but they also are inefficient in many ways, preventing them from remotely coming close to the efficiency required for the tightening emission regulations of the time.
This is where fuel injection proved itself a superior method of fuel metering. Fuel injection atomizes the fuel as it exits the tip of the injector. But even more importantly, with the combined advance in electronics and computer controls, it also provides precise control of the amount of fuel – a critical aspect for fuel economy and emission control.
Indirect Fuel Injection
Indirect means the fuel is injected and atomized before it enters the combustion chamber. Throttle-body injection (TBI), sometimes referred to as single-point injection, is a type of indirect injection in which the injector is located in a throttle body before the intake manifold. The throttle body looks similar to a carburetor and uses many similar components such as the intake manifold and air cleaner.
This was done by design, as it was the most efficient and quickest way for auto manufacturers to make the change to fuel injection, while utilizing many of the same components. Port, or multi-point, injection injects fuel into the intake runner just before the intake valve for each cylinder. Still a form of indirect injection because it occurs before it enters the combustion chamber, the advantage is the ability to precisely control the fuel delivery and balance the air flow into each cylinder, leading to increased power output and improved fuel economy.
Whether an engine is carbureted or fuel-injected, atomization of the fuel is critical for combustion. Many variables affect atomization, and even though a fuel injector initiates the process, the airflow and other objects around it will affect how well the atomized fuel mixes with the air and vaporizes. The location of the injector as well as the design of surrounding components are critical aspects of engine design.
TBI is at a disadvantage because the airflow is interrupted by the injector – another reason that port injection has the advantage and has made TBI obsolete on newer vehicles.
Diesel engines are fuel-injected because diesel fuel doesn’t atomize and evaporate like gasoline. It must be injected into an air stream at high pressure to atomize, and the turbulence of the air is an important factor in causing the air and fuel to mix.
Early on, due to the difficulties of creating an efficient direct-injection system, many diesel engines utilized a pre-combustion chamber that created the necessary turbulence for proper fuel atomization. The fuel was injected into this pre-combustion chamber, making these indirect fuel-injection systems as well.
Direct Fuel Injection
Direct means the fuel is injected directly into the combustion chamber. The challenge with this type of injection is the pressure inside the combustion chamber is much higher than that of the pressure in the intake manifold of an indirect-injection system.
For the fuel to be pushed out of the injector and atomized, it must overcome the high pressure in the cylinder. Indirect systems have a single fuel pump in the tank that provides adequate pressure for the system to operate, usually 40 to 65 pounds per square inch (psi). Direct systems utilize a similar pump to supply fuel to the rail but require an extra mechanically driven high-pressure pump that allows them to overcome cylinder pressure. These systems usually operate at 2,000 psi or higher.
Direct-injection systems can be identified easily by the location of the injectors going directly into the cylinder head as well as the additional lines and mechanical pump, usually visible above the valve cover.
The primary advantage of direct injection is that there is less time for the air/fuel mixture to heat up since the fuel isn’t injected in the cylinder until immediately before combustion. This reduces the chance of detonation, or the fuel igniting from the heat and pressure in the cylinder. This allows a direct-injected engine to have higher compression, which itself lends to higher performance.
Another advantage is reduced emissions and fuel consumption. With indirect injection, fuel can accumulate on the intake manifold or intake ports, whereas with direct injection, the entire amount of fuel sprayed from the injector is the exact amount that will be burned, ultimately leading to more accurate control over the combustion process.
The overall performance and efficiency of direct injection can’t be matched. However, there are still some disadvantages to it when compared with indirect injection. One of the most well-publicized is carbon buildup on the back of the intake valves. Fuel is a great cleaner, and the fuel spray from a port-injected engine keeps the back of the valves clean. Without it, excessive carbon buildup occurs, leading to interrupted airflow into the engine, reduced performance and an expensive repair.
While not an issue for typical everyday driving, indirect injection is limited at high engine rpm because there simply isn’t enough time for the injector to release the fuel and for it to properly atomize. Since port-injected engines spray fuel before or as the intake valve is opening and complete vaporization occurs and the air is pulled into the cylinder, there’s no rpm limit with indirect injection.
Low-speed pre-ignition (LSPI) is a common term you may have heard, and it’s a problem that exposes another chink in the armor of direct injection. The piston and combustion-chamber design of a direct-injected engine is very specific to create the proper air turbulence to completely vaporize the fuel for combustion. At low rpm, the piston is not able to create the proper turbulence, leaving unvaporized fuel pockets that combine with contaminants from oil vapor and carbon buildup, leading to pre-ignition.
While this problem specifically occurs on direct-injected engines, it can worsen with some engine oils depending on the additives they contain. This is why new oils are advertised to prevent LSPI.
As engine technology advanced, diesel engines saw changes in piston and combustion-chamber design that allowed them to make the switch to direct injection and realize the same performance benefits.
So, your two basic types of fuel injection are indirect and direct. There are advantages and disadvantages to both. What’s next? The simplest solution in the book: dual injection. Now manufacturers are building cars with both. Computer control utilizes both systems to eliminate the weaknesses and exploit the strong points of each type of system. It’s the best of both worlds. Wasn’t that easy?
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