September MAY 2012 2012
10 ‘Sensing’ Problems stops If the heater circuit inside an O2 sensor fails, or a sensor producing a signal due to an internal failure or a wiring fault (such as a loose or corroded wiring connector), it will usually set an O2 sensor code. And that’s when you come in. Learn more about O2 sensor relacement in this month’s Component Connection.
10 Common Rail Becomes Commonplace 14 The use of Direct Injection technologies has started to seep its way into the gasoline internal combustion engine market. As this trend in engine design becomes more common, you will need to understand the mechanical, electrical and functional distinctions on these fuel systems to make the correct repairs.
14 22 ‘Braking Bad’ other In this article, we’ll take a look at solving brake noise and undercar complaints on the Mazda line of cars and light trucks. While this work is a mainstay for many shops, addressing the nuts and bolts of this work is beneficial to new techs like yourselves.
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Finish Line: Motorcycle Mentors
Book Report: ‘The Hemi in the Barn’
Tech Tips: O2 No-Nos; Hummer Power Loss Fix
Report Card: The X Factor: McLaren X-1 Takes the Stage
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Tomorrow’s Technician: Dedicated to Today’s Automotive Student
edited by Tomorrow’s Technician staff Each month, Tomorrow ’s Technician takes a look at some of the automotive-related student competitions taking place in this country, as well as the world. Throughout the year in “Finish Line,” we will highlight not only the programs and information on how schools can enter, but we’ll also profile some of the top competitors in those programs. Because there are good students in these events, we feel it’s time to give these competitors the recognition they deserve.
BUILD Program Brings Motorcycle Restoration Into Milwaukee High Schools By Colleen Brousil, editor Motorcycle & Powersports News
Milwaukee, Wisconsin’s Iron Horse Hotel, in cooperation with a team of dedicated volunteers and motorcycle enthusiasts, kicked off the second season of the BUILD Motor Mentor Program earlier this year. Six teams comprised of five students each from area high schools and youth organizations were chosen to fully restore a “barn-find condition” vintage motorcycle to American Historic Racing Motorcycle Association (AHRMA) standards during a 100-day build. Each team
was provided with a pre-restoration condition vintage Honda CB 160/175 and a total of $2,000 in cash for parts. By connecting high school students with skilled mentors and faculty advisors, this after-school program offers students the opportunity to learn vintage bike restoration while developing important business, trade and interpersonal skills. Through a formal and very visible competition, students are rewarded for their efforts with incentives given along the way, recognition
through display and the eventual racing of their bikes. “We’re losing our youth to keyboards and joysticks,” laments program mentor Mark Hoedel. Hoedel, a 17-year powersport veteran, is a vintage restoration expert and has experience as a dealership GM. Hoedel was enthusiastic when he heard about the program launch and is proud to lead team Tech Motor Heads at his alma mater, Bradley Tech. “The motorcycle in itself is a perfect vessel: Everybody thinks a
motorcycle is cool — it draws the kids in. BUILD is so inclusive because it gives the kids the opportunity to not only learn the history of the motorcycle that we’re building, but we get into design, engineering, fabrication, the mechanics and machining. We also talk about budg-
eting and racing and sportsmanship. “The kids are so proud when they’re done. They’ve never dreamt that they’d ever do something like this,” he concludes. In addition to the support of the schools and the community, Hoedel is thankful to the motorcycle indus-
Kevin Krutell Named Mitchell 1’s Automotive Technology Outstanding Student Kevin Krutell from St. Claire Shore, MI, was recently named the 2012 Mitchell 1 Automotive Technology Outstanding Student during the North American Council of Automotive Teachers (NACAT) conference held at Tyler Junior College in Tyler, TX. Each year Mitchell 1 recognizes one U.S. or Canadian high school senior for outstanding achievement in automotive technology and auto shop repair scholastics. Krutell received a $2,500 scholarship, a check for $500 and roundtrip airfare and accommodations for himself and his mother to attend the NACAT conference. “Mitchell 1 is proud to recognize Kevin Krutell for his outstanding achievement and strong dedication to pursuing educational excellence in the automotive technology field,” said Nick DiVerde, senior marketing director, Mitchell 1. “With Kevin’s drive and enthusiasm for making a difference in the aftermarket, we know he will one day accomplish his dreams.” Krutell graduated from Lakeview High School in St. Claire Shores in May, 2012. While in school, Krutell was a member of the National Honor Society, the auto club, the rugby team and the St. Claire Shores ski club, as well as a mentor in the Promoting Academic and Social Success Team. Krutell is currently working as an automotive technician at Jefferson Motor Service. He is enrolled in the automotive program at the Ohio Technical College in Cleveland for the fall 2012 semester and may continue
try for their support of the projects providing free or greatly reduced parts to the BUILD teams. The bikes embarked on a summer tour starting May 31, and the program culminated with a reception at the Iron Horse Hotel featuring a live bike auction on August 30.
his education in their high performance or auto restoration programs. Down the road, he hopes to complete an engineering/business degree and achieve his ultimate goal of one day owning a repair shop. His accomplishments include a first place finish in the brake segment of the regional level of the SkillsUSA competition, and holding the record in the OTC Edelbrock Carburetor Challenge with a dissemble and reassemble time of five minutes, 51 seconds. He also took the online exam portion of the Ford AAA Automotive Competition and he and another student were one of 10 teams from Michigan to move to the hands-on level of the competition. “My reasons for wanting a career in the automotive field are simple,” said Krutell. “I like working with my hands, finding and solving problems and being able to install parts on cars to make them into whatever I or the car owner want. I can then step back, admire my work and see the joy it brings to other people. I hope to think differently and push further, blending technical and academic achievements to help combine performance and fuel efficiency in the automotive aftermarket field.” Krutell hopes to lead his generation to new advances in the automotive alternative fuels field. By utilizing aftermarket parts in addition to new hybrid technologies, he hopes to one day build the race car, hot rod or tuner of the future.
Do you have an outstanding student or a group of students that needs to be recognized for an automotive-related academic achievement? E-mail us at email@example.com.
Sensing Failures Knowing When to Replace O2 Sensors Adapted from Larry Carley’s article in
The oxygen (O2) sensor is part of the fuel management system, developed to monitor unburned oxygen in the exhaust. And, the powertrain control module (PCM) uses this information to determine if the fuel mixture is rich (too much fuel) or lean (not enough fuel). To provide the best performance, fuel economy and emissions, the PCM has to constantly readjust the fuel mixture while the engine is running. It does this by looking at the signal from the O2 sensor(s), and then increasing or decreasing the ontime (dwell) of the fuel injectors to control fuel delivery.
The Heat is On
Oxygen sensors don’t produce a signal until they are hot, so the O2 sensors in most late-model vehicles have an internal heater that starts heating up the sensor as soon as the engine starts. Older, first-generation O2 sensors lacked this feature and took much longer to reach operating temperature, which increased cold-start emissions. Once the sensor is hot, a zirconiatype O2 sensor will generate a voltage signal that can range from a few tenths of a volt up to almost a full volt. When there is little unburned oxygen in the exhaust, the sensor usually generates 0.8 to 0.9 volts. The PCM reads this as a “rich” signal, shortens the duration of the fuel injector pulses to reduce fuel delivery, and leans out the fuel mixture. When there is a lot of unburned oxygen in the exhaust — which may be from a lean fuel mixture, or if the engine has a misfire or compression leak — the O2 sensor will produce a low-
voltage signal (0.3 volts or less). The PCM reads this as a “lean” signal, increases the duration of the injector pulses, and adds fuel to enrich the fuel mixture. A slightly different variation on this is the titania-type O2 sensor. Used in some older Nissan and Jeep applications, this type of sensor changes resistance rather than producing a voltage signal.
In recent years, the design of O2 sensors has changed. The ceramic thimble-shaped element in zirconia-type O2 sensors has been replaced by a flat strip ceramic “planar” style sensor element.
Did you know oxygen sensors have been used for about 30 years, dating back to 1980, when the first computerized engine control systems appeared? While the basic operating principle is still the same (the output voltage changes as O2 levels in the exhaust change), the new design is smaller, much more robust and faster to reach operating temperature. You can’t see the difference from the outside because the tip of the sensor is covered with a vented metal shroud, but many O2 sensors from 1997 and up use the planar design. Another change has been the introduction of “wideband” O2 sensors, which are also called “Air/Fuel” or A/F sensors. This type of O2 sensor also uses a flat strip ceramic element inside, but it has extra internal circuitry that allows the sensor to measure the exhaust air/fuel ratio with a much higher degree of preci-
Component Connection sion. It can tell the PCM the exact air/fuel ratio, not just a gross rich or lean indication as other O2 sensors do.
In 1996, vehicles also began using oxygen sensors to monitor the operation of the catalytic converter. A “downstream” O2 sensor is placed either in or just behind the converter to monitor oxygen levels after the exhaust had reacted with the catalyst. If the operating efficiency of the converter drops below a certain threshold that might cause an increase in emissions, it sets a diagnostic trouble code for the converter and turns on the check engine light. First-generation O2 sensors typically have a limited service life, and may need to be replaced for preventive maintenance somewhere between 50,000 and 80,000 miles. O2 sensors on 1996 and newer vehicles typically have a much longer service life of 100,000 miles-plus, and do not have to be replaced unless they have been contaminated or damaged. When O2 sensors get old, they can become sluggish and slow to respond to changes in exhaust oxygen levels. Typical symptoms include a drop in fuel economy and higher exhaust emissions. A bad O2 sensor should not affect engine starting, cause a misfire (unless the spark plugs become carbon fouled), or cause engine stalling or hesitation problems. A sluggish or fouled O2 sensor will typically read low (lean) and cause the engine to run rich. O2 sensors can be fouled by silicates if an engine has an internal coolant leak and the cooling system contains a conventional antifreeze with silicate rust inhibitors. The O2 sensor can also be contaminated by phosphorus and zinc from motor oil if the engine has an oil consumption problem (worn valve guides or piston rings).
If the heater circuit inside the O2 sensor fails, or the sensor stops producing a signal due to an internal failure or a wiring fault (a loose or corroded wiring connector), it will usually set an O2 sensor code (P0130 to P0147). The codes can be read by plugging a scan tool into the vehicle’s diagnostic connector. But many times, other engine problems will set codes that may seem to indicate a bad O2 sensor, but in fact do not. A P0171 or P0174 lean code, for example, means the O2 sensor is reading lean all the time. The real problem may not be a bad O2 sensor, but possibly an engine vacuum leak, low fuel pressure or dirty fuel injectors that are causing the engine to run lean. An engine misfire, leaky exhaust valve or a leak in the exhaust manifold gasket that allows air into the exhaust may also cause this type of code to be set. If an O2 sensor has failed and needs to be replaced,
some aftermarket replacement sensors require splicing the sensor wires to accommodate all the different OEM connector styles. This type of O2 sensor provides greater coverage with fewer part numbers. Others come with the same style connector as the original and are easier to install, but require many more part numbers for the same coverage. Ever wonder what causes O2 sensors to fail? As O2 sensors age, they slow down. But this usually isn’t a factor until the sensor has upwards of 75,000 or more miles on it. As more vehicle owners hold onto their cars and trucks longer, replacement of O2 sensors on some of your regular customers’ vehicles can be expected. But, when an O2 sensor fails prematurely, the cause is often contamination. Contaminants can come from a number of sources. If the engine has an internal coolant leak (due to a crack in the combustion chamber or a leaky head gasket), and the coolant contains silicate corrosion inhibitors (which conventional green coolants do, but long-life orange coolants such as Dex-Cool do not), the silicates can pass into the exhaust and contaminate the O2 sensors. Another source of contamination is the anti-wear ingredients in ordinary motor oil. The amount of phosphorus and zinc in motor oil has been reduced in recent years to reduce the risk of O2 sensor and catalytic converter contamination. Every engine uses a small amount of oil, and over time the contaminants can add up. As the engine accumulates miles, and the valve guides, rings and cylinders start to wear, oil consumption goes up. Consequently, in a highmileage engine that is using oil, phosphorus and zinc, contamination of the O2 sensors and catalytic converter can be a problem. If the O2 sensors are sluggish or have failed, they obviously need to be replaced. But, replacing the O2 sensors will only temporarily restore the fuel feedback control system. Unless the oil burning is eliminated, the new O2 sensors will eventually suffer the same fate.
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By Omar Trinidad, Assistant Professor, Southern Illinois University Carbondale
Become Commonplace Gasoline Direct Injection Gets a Boost in Fuel System Designs Due to the conflict between consumer performance demands and more stringent EPA standards, the use of Direct Injection technologies has started to seep its way into the gasoline internal combustion engine (ICE) market. This trend can be seen through products such as the Ford Taurus, Volkswagen GTI and the Lexus IS lineup. With rumors about corporate average fuel economy (CAFE) requirements increasing to the 40 and 60 miles per gallon range by 2025, the use of Gasoline Direct Injection (GDI) is here to stay. Now the question is: how will this affect the service side? There are several mechanical, electrical and functional distinctions that technicians need to know when working on GDI vehicles. Furthermore, numerous issues have sprung up over the years concerning fuel system problems and deposit buildup on the intake valves.
Mechanical At first glance, a GDI engine appears mechanically similar to a non-GDI system. But it starts to look very different once the plastic covers are removed and the electronics are tested. The first oddity to
Under the Hood be seen is a solenoid-controlled mechanical fuel pump that can step up fuel pressure from 65 psi (448 kPa) to anywhere between 220 and 2,150 psi (1,516 and 14,823 kPa), see Figure 1. The low pressure side still utilizes an electric fuel pump and a returnless configuration similar to the Port Fuel Injector (PFI) systems. A module monitors a fuel pressure sensor on the low pressure side to control low-side fuel pressure. The same module also controls a spill valve Figure 2 solenoid to control high-side fuel to switch up to five times faster than pressure. the conventional solenoid type injecA special gasoline direct injectiontors. GDI injectors are designed with fuel system tester (DI-FST), which nozzles that spray at an angle to is about $1,400, will be needed for allow the fuel to swirl within the diagnostics. cylinder. This swirl effect allows for For most GDI vehicles, the fuel injectors are very difficult to access. a better mixture and an increase in Most manufacturers are utilizing low efficiency. The swirl effect is further impedance (low resistance) injectors increased with the use of specially for their quick response. But, it is shaped pistons and vanes in the very possible that the manufacturers intake runner. Although there are great benefits will soon start to integrate piezo from having the lean burn attribute injectors, currently used in common of the GDI systems, they are more rail diesel applications, that are able susceptible to cold-start problems. To address this problem Lexus has designed its six-cylinder 2GR-FSE engine, found in the IS350, GS350 and GS450h models, with six direct injectors and six port injectors. The port injectors are utilized in conjunction with the direct injectors to improve cold-start conditions and increase power by richening the air/fuel mixture. For the six-cylinder 4GR-FSE engine, found in the IS250, Lexus designed the engine with only a cold-start injector to compensate for cold-start situations.
Electrical Direct injection systems are actuated very differently from conventional PFI systems. Most manufacturers utilize a higher voltage, two shared power drivers and individual ground drivers. It is normal to see voltage readings of 60-65 volts on these systems. 09.12
The computer, usually the Power Control Module (PCM), utilizes capacitors and several transistors to step-up the voltage and control injector on-time. Toyota actuates its injectors through an Injector Driver Unit (EDU). In this system, the PCM indicates to the EDU when and how long to turn on each injector. The initial high voltage is only used to open the pintle. After the high voltage peak, the voltage drops to charging voltage and the PCM or EDU controls the pulse width to control injector current flow (Figure 2). The current ramps up after the high voltage peak and dramatically drops when voltage drops to 12 volts. The amperage never drops to zero until the injector is fully off. Unlike non-GDI systems, each injector is controlled on both the positive and negative side of the circuit. In addition, most systems are designed with two injectors sharing two positive drivers. One driver is used for the high voltage needed to open the pintle and the other used for the lower voltage used to keep the injector open. Figure 3 illustrates a simplified schematic of the system. This is similar to the paired cylinders design used on waste-spark ignition systems. One of the advantages to pairing two injectors together is the utilization of the sister cylinders inductive kick to recharge the capacitor.
Under the Hood While the scope patterns might look odd compared to non-GDI systems, technicians can still apply their scope reading diagnostic knowledge to diagnose GDI faults. The best way to use a scope on a GDI system is to focus mainly on the amperage readings while using the voltage readings as a guideline. Due to the high voltage used on the GDI system, technicians must be cautious when using an oscilloscope. Technicians must always use
an attenuator to prevent any harmful voltage spikes from harming the oscilloscope. Furthermore, caution must be used when using multichannel oscilloscopes due to their common ground design. Some manufacturers do not specify the positive and negative side of their injector circuit. This might lead to some confusion, causing the common ground within the oscilloscope to complete the circuit between two injectors being tested.
Some technicians diagnosing a misfire on a GDI vehicle might be stumped by the scope reading shown in Figure 4. The scope pattern illustrates how the current reading skips every voltage reading due to the sister cylinder design.
Under the Hood Functional
the air/fuel mixture is closer to stoichiometric or slightly richer. Homogeneous lean is used when the air/fuel mixture is leaner.
Each manufacturer has designed its GDI systems to function with several modes to increase efficiency or power. This is accomplished by controlling when and how long the injectors are turned on. Although each manufacturer identifies its GDI system with its own terminologies and modes, homogeneous and stratified are two terms that most manufacturers adopt to distinguish air/fuel mixture strategies. Homogeneous, also known as homogeneous charge, is the term used when the air and fuel mixture is injected during the intake Figure 5 stroke. This allows for an evenly Stratified, also known as stratified distributed air/fuel mixture that is applied when more power is needed charge, is the term used for an air and fuel mixture that is injected duror to warm the engine and catalytic converter. Homogeneous stoichioing the compression stroke. The metric is the terminology used when stratified charge allows the GDI sys-
tem to achieve its highest efficiency gains through ultra lean air and fuel mixtures in the 60:1 or higher range. More efficiency gains can be achieved by utilizing electronic throttle control and variable valve timing. Some manufacturers have designed throttleless engines that eliminate the need for the throttle butterfly as a way to increase efficiency by decreasing what engineers refer to as â€œpumping loss.â€?
GDI Issues Although there are numerous advantages with GDI, there are several issues that must be addressed. GDI systems have experienced fuel delivery system and intake valve carbon deposit buildup issues that cause driveability and performance problems. Several recalls and TSBs have been implemented to resolve these issues. Volkswagen experienced cam follower failures in its Fuel Stratified Injection (FSI) engine caused by excessive friction and design flaws (Figure 5). The worn cam follower would fail and allow the fuel pump shaft to rest directly onto the cam lobe. This would cause the cam lobe to wear and fuel pressure to decrease. This problem would normally cause the MIL to illuminate. The cam follower issue was corrected in the Turbo Stratified Injection (TSI) engine by utilizing a roller design cam follower instead of the tappet type. In addition, Volkswagen published TSB 2015153 to resolve this issue on the FSI engines. One of the first signs of a failing cam follower is a code P0087 (Fuel Rail/System Pressure Too Low). This code is usually accompanied by driveability issues, loss of power and lower fuel economy. Most P0087 problems are associated with a mechanical failure in the fuel pump system. However, this code can also be caused by sensor failure and other electronic issues. 09.12
Under the Hood Carbon deposit buildup on the intake valve was one of the unforeseen issues prior to the implementation of the GDI system (Figure 6). Previously, PFI systems sprayed fuel before or onto the Figure 6 intake valve. This allowed the fuel to clean the valve every time it sprayed fuel into the port. Conversely, the GDI systems inject the fuel directly into the cylinder, leaving the intake valve vulnerable to deposit buildup. This issue has been prevalent since its inception. However, the problem has started to become more apparent in the industry due to the recent increase of GDI vehicles. The carbon buildup in the GDI systems can be associated with valve seal seepage, positive crankcase ventilation (PCV) fumes and unburned fuel from the swirling air/fuel mixture in the cylinder. Figure 7 is a picture of an intake valve from a GDI vehicle that was cleaned 10,000 miles earlier. Notice that the deposits are on the valve stem and intake manifold port walls. Although the deposits on both the intake valve and manifold can be associated with fumes from the PCV system and unburned fuel, the deposits on the valve stem can also be attributed to valve seal seepage.
Symptoms relating to excessive carbon buildup are very similar to carbon buildup problems on nonGDI systems. Depending on the TOMORROWSTECHNICIAN.COM
severity of the problem, excessive carbon buildup can cause random misfires, decrease in fuel economy, rough idle, long cold starts and a lack of power. The measures that have been taken to service the intake valve deposit problem span from induction system cleaning solutions to cylinder head replacement. In a Lexus TSB, L-SB-0029-10, technicians were instructed to pour a cleaning solution inside the cylinder. Similarly, companies such as BG have developed GDI cleaners that require less engine disassembly. Some manufacturers are using walnut shells as an abrasive to clean the deposits. There have been cases where the valves were severely coated with carbon and were not sealing properly. In those cases, the cylinder head was replaced with a new or refurbished cylinder head. As the number of GDI vehicles on the road increases, it is very important for new technicians to understand the various systems and have the proper diagnostic tools to service these vehicles. Caution must be taken when working on the highpressure side of the fuel system. Furthermore, it is very important to monitor both current and voltage with an oscilloscope to diagnose fuel injector malfunctions. There are always advantages and disadvantages when technology advances. For now, the next step is GDI. 09.12
Br aking Ba d:
Solving Mazda Noise Complaints Adapted from Bob Dowie’s article in
In this article, we’ll take a look at brake and undercar service on the Mazda line of cars and light trucks. Since this work is a mainstay for many shops, the nuts and bolts of this type of work should be routine to all but the newest techs like yourselves. With some of those folks cutting their teeth in the shop doing this kind of work, we’ll cover things that will help the rookies while reminding the more experienced techs of this fact: While brake and chassis work can become routine, good work habits are critical for a successful job from beginning to end.
Undercover Every job should start with the customer interview. When the appointment is made, it’s important that some questions that will help ensure a successful job get answered. The first question to ask is why the customer thinks the brakes need service. What is obvious to us is a mystery to the customer so it’s important that we establish what it is that has the customer concerned. There is nothing more disappointing to a customer than to spend money on a repair and not have their concerns addressed. And, with the brakes being the most important safety system in a vehicle, you don’t want folks driving for a week with the brakes metal to metal. If you’re operating a successful shop, you are probably already focusing on preventive maintenance and all of your techs, as well your customers, are aware of the benefits of that practice. Your regular clients are expecting that the brakes will be at least visually inspected whenever the car is in for service and it’s up to you not to disappoint them. Anticipating and pointing out service that will be needed in the future isn’t selling as much as it is performing a valuable service. It is beneficial for both the shop and the customer to anticipate future services, allowing them to tie up the car when it’s convenient for them, while you keep the bays full with scheduled work. Brake problems will present themselves in a couple of ways. The most common complaints are noise-related. Mazdas, like many other manufacturers, make use of the simple and effective tab-type sensor that will contact the rotor when the pads need to be replaced. The resulting, high-pitched squeaking noise has proven to be very effective in getting drivers’ attention. That’s not to say that
drivers won’t ignore it and drive until the brakes are making that distinctive grinding noise that indicates the friction material is gone and metal-to-metal contact is taking place. Of course, in that case, the car should be parked until repairs are made. Many of the occasional, annoying noises that disc brakes make are a small trade-off for the braking performance delivered by the system. Oftentimes, just explaining that to a customer goes a long way toward settling any concerns that something is wrong with his/her brakes. But, any noise that is more than occasional should be investigated. Some noise will be the result of rust on the rotors, calipers, hardware or even the brake pads themselves. Use only the best parts, replace questionable units and make sure that the brake hardware is in good condition or new. This is particularly important with Mazda 3s and 6s that have some problems with the hardware contacting the rotors. There have been some tech bulletins related to this issue so be sure to check your service info. Also make sure that all the metal-to-metal contact areas are lubed with the proper grease that’s designed to do this tough job in a harsh environment.
The first step in any brake inspection should be a test drive, as it’s always a good idea to confirm the customer’s complaint. The test drive will also let you note any other issues with the car that should be addressed while the brake service is being performed. Again, on the Mazda 3s, wheel bearing failures are fairly common and the noise will come on gradually and is often overlooked by the customer. If you’re going to have the brakes apart, this is the time to take care of the wheel bearings. The same can be said for sway bar links. Oftentimes, just letting the customer know that the cause of that banging noise can be taken care of at a reasonable cost will motivate the repair. I think we all agree that it’s more efficient to know the noise is there before the car is on the lift. Of course, you will also be looking for rotor vibration/pulsation, a long pedal or pulling that would be
Tell-Tale SIgNS: leaking calipers or wheel cylinders always leave visual evidence, so inspect the brake hoses and if they need to be replaced, now is the time to take care of it. If you suspect a sticking caliper, take the time to confirm it. Pads that are seized in the brackets or frozen sliders will mimic a bad caliper, even though hydraulically the caliper is fine. 24
Undercover directly related to the brake system. The inspection continues back at the shop and on the lift. It shouldn’t take long to establish that the vehicle needs brake service, but before you call to get authorization from the customer, spend a few minutes so you can provide an accurate estimate. I’ve never had a customer who enjoys getting that surprise phone call that more problems have been found. Spin and shake the wheels before they come off. Any excessive drag should be noted and, it goes without saying, that any looseness in the steering should be investigated and reported. The same goes for cracked CV boots or leaking struts. With the wheels off, it doesn’t take long to get a good look at the pads and rotors. Read them for additional information, and look for signs of overheating or uneven wear indicating a sticking caliper or pads.
equipped with ABS, there is little tolerance for contaminated fluid being pushed back through the system and that sensitive modulator unit. You are going to be bleeding and flushing the system as part of the service, so there is no time lost in this step. And, if the bleeder can’t be opened or needs to be cleaned, it’s better to find out now rather than after the caliper has been serviced and new pads have been installed.
Questioning the Customer The most common brake-related vibration is that which occurs while braking and is caused by disc thickness variation. Ask your customer some questions that could help ensure a quality job. When did you notice the problem, and was there any action that led to the problem? Did you have any tire work done lately? If so, it’s likely you’ll find that the lug nuts are unevenly tightened. To confirm this condition, loosen the lug nuts by hand. More often than not, the overtightened nuts will be obvious.
After the car has been inspected and the job has been sold, it’s time to get to work. As I mentioned earlier, brake work is routine for the most part for most of us, but it’s important that solid work habits are used from the beginning to the end of the job. Be sure to open the bleeder valves before the pistons are pushed backed into the caliper. With most cars today being
The biggest enemy of the rotor is heat. The rotor has a tough job on a system that’s in good shape, but it doesn’t have a chance on a system that has excessive, heat-causing
Undercover drag. Take a good look at the rotors as they’re removed for signs of overheating. It makes little sense to install fresh parts only to subject them to the same conditions. It could be that the last tech who did the brakes didn’t get the caliper brackets clean or missed a point that should have been lubed. More likely, the increased mileage has caused a problem. Either way, if it’s not corrected, your new rotors will soon be in the same shape as the ones you just took off. This leads us to more discussion on work habits. Be certain that all the areas where pad movement takes place are cleaned and lubed. Don’t overlook the area under the tin pad brackets; rust buildup here will result in tight-fitting pads. Also be sure the caliper slides are inspected, clean and lubed. This is important not only for smooth, quiet brake operation, but it is critical for the ABS to operate as expected. Being located in the Northeast, we see firsthand how the harsh environment can be on the brake system. In extreme cases, you may find that it’s more cost effective to replace the calipers rather than spend the time required servicing the originals.
highway speeds, it’s likely that excessive drag is causing the fluid in the calipers to overheat, resulting in brake fade. When the brakes cool, the pedal often will return to what feels like normal to the customer. Many times, the customer will report a burning smell and, in the worse cases, will cause a severe vibration. It takes a stuck caliper to generate the degree of heat needed to cause these problems, and they certainly should be checked closely. You should be able to find the problem wheels by inspecting the rotors. If that much heat was generated, the calipers, as well as the rotors, will show the signs. If you can duplicate the tight wheel, don’t be too quick to condemn the caliper without cracking open the bleeder to be sure there’s no pressure in the line.
Delving into the Job
If pressure exists, backtrack through the hydraulic system until the restriction is found. It could be a collapsed brake hose acting as a one-way valve, or you may work your way back to a contaminated ABS modulator. It’s always a good practice to replace any brake hose that was subjected to extreme heat, even though it may look OK and not leak. There is no “brake pedal sometimes way to know if the integrity of the crimps fades to the floor” were comprised, so for a few dollars it’s better to be safe than sorry. With high-mileage vehicles, you Mazda uses a hand-brake that is could be faced with a “brake pedal incorporated into the rear caliper. sometimes fades to the floor” comThey use a couple of systems to plaint. Although it’s not a common complaint on Mazdas, a little detec- retract rear pistons. The latermodel cars require the familiar tive work is required in such cases. method of turning the piston If the pedal fades as the vehicle clockwise while applying pressure, comes to a stop, often in a situation where others will have a plug on where the pedal is being partially the back side of the caliper that applied in anticipation of coming to provides access for an Allen a full stop, it’s a safe bet the master wrench to facilitate retracting the cylinder is the culprit. piston, but be careful as you If, on the other hand, the condiretract the piston. tion results from a long ride at 09.12
Undercover We know everyone doesn’t use his or her hand-brake on a regular basis, and we also know that a mechanical device doesn’t like to sit around not being used, only to suddenly be forced into service. The same thing can be said for the cables. If the hand-brake levers aren’t returning on the caliper, be sure that the cables aren’t binding. The complexity of the hand-brake does make the rear calipers a little pricier, but I still like to replace them in pairs to maintain the balance of the brake system. Finish off with a good bleed and flush of the hydraulic system, torque the wheels and the car should give the customer many miles of trouble-free braking.
followed by a short flash represents a code 11 for a right front speed sensor circuit problem. To clear the code, go through the same procedure waiting for the codes to be displayed. When the first code is displayed a second time, hit the brakes 10 times at onesecond intervals. If the code won’t clear, be sure the brake light switch is working as expected. Be aware that if the repair involved a wheel speed sensor or control unit repair, the light will stay illuminated until the car is driven over six miles per hour. With 2004 and newer models, you’ll need a scanner with the capability of accessing the ABS system to retrieve codes. Hopefully by now, CheCk The ReCoRdS: as always, it never your shop has made the investment in the necessary equipment, as hurts to check your service information. there are plenty of affordable options available and it’s simply foolish at this point to try and get by without the necessary tools. Scanning for Clues As I mentioned earlier, we have been seeing some When it comes to the ABS system, Mazdas have proven wheel bearing failures on the popular Mazda 3 models. to be very reliable, but that’s not to say they never have The nuts and bolts of the replacement procedure shouldn’t a problem. Codes can be retrieved on the early model present a challenge for most techs, but it’s important to cars by grounding terminal 13 in the datalink -1 conneckeep in mind that the bearings are directional and have tor that can be found under the hood. Install the jumper to be installed with the internal tone ring facing the ABS with key off, and when you turn the key on, the ABS sensor. lamp will be lit for three secMost bearings are colored-coded with the green seal onds before you get the being installed toward the sensor. Since the tone ring is familiar flash codes — magnetic, you can confirm the proper direction by laying with the long flashes a clean piece of paper on the bearing and sprinkling some representing tens shavings from the brake lathe on the paper. It will be and the shorts easy to tell which side is magnetic and, needless to say, being ones. For it’s critical that the shavings do not find their way into example, one the bearing. long flash End stop
1. Underbody components, collectively 5. ‘60s gas slogan, “Put a ____ in your tank” 8. Gear or compression trailer 9. Dashboard channel (3,4) 10. Toddler’s Tonka-truck terrain 11. Under-dash area 13. Clutch components 14. Major engine castings 17. Big-rig wheel count, often 19. Gear teeth 22. RWD car’s differential, slangily (4,3) 23. Budget and Hertz rival 24. OBD scan-tool data 25. Alignment-rack measurement, maybe (4,3) Down 1. Components returned for rebuilding 2. Radio adjunct in auto glass, often 3. Brake-system footwear 4. Auto-tool brand since 1920 (4,2) 5. Accelerator 6. Dash dial 7. Old-car noises, often 12. Motorcyclists’ attire, often 13. Post-1977 tire-sizing system (1,6) 15. Antifreeze and water mixture 16. Power-boosting exhaust manifold 18. Brinks-truck occupant 20. Oil-burner’s output 21. Aftermarket auto-parts retailer
Tomorrow’s Technician September Crossword
Solution at www.tomorrowstechnician.com © M urray J ac kso n
BOOKREPORT The Hemi in the Barn It’s every car lover’s fantasy: the perfectly preserved classic automobile discovered under a blanket in some great-grannys garage. And as Tom Cotter showed us in The Cobra in the Barn, it’s a fantasy that can come true. Cotters’ adventures in automotive archaeology continue in The Hemi in the Barn, with more than forty new stories of amazing finds and automotive resurrections. Avid collectors big and small recall the thrills of the hunt, the tips and hunches followed, clues pursued, the heart-stopping payoff. There’s the forgotten Duesenberg — the only unrestored one around — that Jay Leno found in a Burbank garage. There’s another 1931 model Dusenberg Leno found in a parking garage in New York City that was parked in 1933 and was never moved. There’s a Plymouth Superbird found buried in a hedge out of sight in Alabama. There’s the rescue of the first 1955 Corvette ever built. There’s the find
some are truly corkers — they’re also full of tantalizing hints and suggestions for readers setting off on their own adventures in automotive archaeology. A great read for automotive history buffs, as well as those who enjoy learning about automotive “treasure” finds. The book also is chalked full of automotive trivia and would complement any automotive student’s bookshelf. It also would make a great gift for a favorite auto instructor.
of legendary race builder Smokey Yunick’s Boss 302 Trans-Am car. And, there’s the story of the original Cobra Daytona Coupe built by Peter Brock and sold to Phil Spectre — a story that somehow involves a chauffeur’s daughter setting herself and her rabbits on fire. As entertaining as these tales are — and
Book Notes: Author: Tom Cotter Foreword by: Jay Leno Format: Hardcover, 256 Pages ISBN: 9780760327210 Illustrations: 104 color & 31 b/w photos Size: 6 x 9 Price: $19.46 plus S & H Publisher: Motorbooks To order: http://www.motorbooks.com/
This month’s Tech Tips are sponsored by:
02 No-Nos: Proper Handling Tips for Oxygen Sensors • DO NOT drop or use an oxygen sensor that has been dropped as this may have caused shock damage to the ceramic element; • DO NOT use any compounds on or around the sensor unless labeled as oxygen sensor friendly products; • DO NOT use an impact wrench or conventional socket type wrench to install the sensor; • DO NOT allow the sensor or lead wire to touch
the exhaust manifold or any other hot component; • DO NOT expose this product to water, oil, windshield cleaner, anti-corrosion oil, grease, terminal cleaner, etc.; • DO NOT use leaded fuels, silicone or metalbased additives; and • DO NOT store under high humidity conditions. So urc e : N TK O xyge n Se nso rs
Finding a Fouled Up Fuel Gauge Affected Vehicles: 2007-’10 Nissan Sentra If you confirm the fuel gauge is erratic, inaccurate or inoperative and/or the MIL is on with DTC P0461, P0462 or P0463 stored in self-diagnosis, replace the fuel lever sensor unit (P/N 25060ZJ60A). N ote: Do not replace the entire fuel pump module assembly for this incident, if it should occur. Service Procedure Fuel Lev er Sensor R emov al 1. Remove the fuel pump module assembly. N ote: Perform repairs in a clean work environment.
2. Remove the three wire terminals with red, white and double-wire black wires from under the top of the module. N ote: The white wire may appear yellowish in color. – Press the tab in and then gently pull the wire off its terminal. 3. Remove all wires from under both retention features on the module. See Figure 1 4. Remove the fuel tank temperature sensor from its retention feature. 5. Remove the fuel level sensor from the module. See Figure 2.
2. Install the temp sensor into its retention feature. 3. Install the four wires into the first retention feature. 4. Route the same wiring as shown in Figure 3.
5. Install the wiring into the second retention feature. 6. Install the wires to the correct terminals as shown in Figure 4.
– While pushing the tab inward (1), push the level sensor up (2), and the pull the level sensor away from the module.
Fuel Level Sensor Installation 1. Install the new level sensor onto the module. – Perform Step 5 in reverse, making sure its tab locks into place. TOMORROW’S TECHNICIAN
– Route the wiring on the outside of the fuel line. – Make sure the tabs are securely locked. 7. Re-install the fuel pump module assembly with new packing (O-ring seal). Co urte sy o f M itc he ll 1.
McLaren Automotive’s special operations department introduced the McLaren X-1 Concept at The Quail, A Motorsports Gathering near Pebble Beach, CA, in mid August. The McLaren X-1 is based structurally on the company’s groundbreaking carbon MonoCell, but with a totally unique body that was created for an anonymous car enthusiast. According to McLaren Special Operations (MSO) design director Frank Stephenson, the styling took 18 months to finalize. Stephenson said the X-1 is the most ambitious example yet of MSO’s expertise, adding the car has a whole new body made of advanced materials. Everything on the vehicle
was made to the buyer’s specifications, even down to the lights and wheels, necessitating new testing and track time. The car took two and a half years to build, a process that began before the styling was even signed off. “The client was very clear in his own mind what he wanted. But the only styling feature prescribed were metal brightwork rails running from the nose, over the shoulder line and hips, to the rear of the greenhouse,” said Stephenson. The X-1 had its own development program because this wasn’t to be a fragile concept car that would never see tarmac. Rather, it was developed to be a usable car, road legal and capable of travelling at supercar
speeds. It also had to comfortably seat two adults. A full CFD (Computational Fluid Dynamics) aerodynamic testing schedule ensured high-speed stability, and the car also completed approximately 625 miles of testing, including two intensive testing stints at the Idiada circuit in Spain with chief McLaren test driver, Chris Goodwin. All body panels of the X-1 are made from carbon, and are finished in a rich piano black, as specified by the owner. Body sides are lacquered visual carbon fiber. “The black paint has no metallic or color tints and is one of the most challenging colors to paint, but the finish is absolutely exquisite and befits the car perfectly,” said Stephenson. Components were tooled exclusively for the car. They even include unique head- and taillights, inspired by the McLaren Speed Marque logo. The brightwork is machined from solid aluminum, and a nickel finish is then
applied. The McLaren logo in the nose is specially machined from solid aluminum then nickel-plated. Wheels are also unique to the X-1, and are diamond turned with a tinted lacquer to complement the exterior nickel-plated brightwork. Perhaps the most unusual styling feature is the enclosed rear wheels, an upshot of the owner’s desire to have a car reflecting “timeless elegance.” The wheels are accessed by carbon panels using unique hinges. The X-1’s powerplant is similar to the McLaren MP4-12C that uses a 3.8L V8 bi-turbo aluminum engine with variable valve timing pumping out 600 hp. 09.12
Published on Sep 12, 2012
Tomorrow’s Technician delivers technical information about servicing today’s vehicles to a target audience of 17-to-25-year-old automotive v...