March 2010 Archives

As emissions standards continue to grow stricter, more devices have been added to vehicles to decrease pollutants, ranging from the catalytic converter to exhaust gas recirculation (EGR) and variable valve timing (VVT). Many of these innovations have focused only on emissions; however, variable valve timing has provided a way to help control major pollutants while increasing torque and horsepower through finer control of engine operation. (Fig. 1)

At engine combustion chamber temperatures above 2500°F, nitrogen mixes with oxygen to form oxides of nitrogen (NOx), a major contributor to smog. Because each cylinder experiences combustion temperatures well above that level, a goal for all automotive manufacturers has been to reduce combustion temperatures. 

The use of an EGR valve was an early method for reducing the formation of NOx. Exhaust gas is reintroduced into the intake manifold through a valve, diluting the intake charge and effectively reducing combustion chamber temperatures and the formation of NOx. A side effect of introducing external EGR to reduce NOx is that it causes the hydrocarbon (HC) levels to increase. 

Internal EGR 

A more effective method of controlling emissions is to increase intake and exhaust valve overlap, a version of internal EGR. Valve overlap refers to the amount of time in the four-cycle engine event when both the intake and exhaust valves are open. A reversion occurs in the cylinder as the piston is moving down while both valves are open. Exhaust gas is drawn back into the cylinder, simulating an EGR function. Being able to control the length of this event can substantially lower NOx. HC levels are also reduced by re-burning the tail of the exhaust event that is rich in hydrocarbons. However, placing the camshafts in a permanently increased overlap position would affect idle and low rpm performance. The greater the overlap, the lower the intake manifold vacuum levels. 

Fixed camshafts compromise between smooth idle, good low-rpm torque and high-rpm power. But variable camshaft timing accommodates the sometimes divergent needs for power, drivability, economy and emission control. 

Variable valve timing uses a cam phaser to dynamically change valve timing events relative to piston timing by controlling the camshaft. This allows the position of the camshaft to be changed, dependent on need. At idle and low engine load, overlap is minimum, improving idle quality. At higher engine speed and load, overlap is increased, allowing emissions to decrease. 

The cam phaser allows the PCM to change the relationship of the camshaft relative to the crankshaft, permitting better control over emissions and performance. 

Splined Phaser 

Early cam phasers used a splined phaser, which uses an internal piston that connects the exhaust camshaft and cam phaser sprocket together using helical splines, forming an adjustable mechanical link. The swivel action of the cam phaser (or Exhaust Camshaft Position Actuator) is accomplished via oil pressure applied by an oil control solenoid into the actuator's piston in the hub of the camshaft sprocket. 

A PCM commanded control valve manages the oil pressure to the cam phaser internal piston. The internal piston rides along the helical splines, rotating the cam phaser gear and the camshaft opposite of each other, changing cam timing. 

A spring within the cam phaser holds the piston in an advanced position (0°) when no oil pressure is applied. This allows the engine to start and run with the cam in the home position. When cam phasing is desired, the PCM can retard the cam position up to 25° (50° of crankshaft angle) by varying oil pressure to the piston through the control valve. (Fig. 2) 

Vane Phaser 

Later VVT systems on some twin-cam engine designs use a vane phaser on each camshaft. Inside the vane-style actuator assembly are a rotor and stator that are not mechanically linked together. Instead, oil pressure is controlled on both sides of the vanes of the rotor, giving a hydraulic link to the stator. Varying the balance of oil pressure on each side of the vanes is how the cam is phased. (Fig. 3) 

At idle, the exhaust cams operate at full advance, for minimum valve overlap. Optimizing valve overlap eliminates the need for a separate EGR system and air injection reaction (AIR). 

The camshafts are driven by a roller chain. A hydraulically operated tensioner keeps proper tension on the chain, even as it stretches with mileage (a normal occurrence in all chains), which eliminates need for periodic replacement or adjustment. The cams operate directly on roller-finger followers, which actuate the valves. 

A return spring sits under the reluctor of the actuator to help keep it at a 0° (home) position. The actuator contains two cavities for oil to flow into to either retard or advance the cam. The four-way PWM oil control valve (OCV) controls which cavity receives pressurized oil. (Fig. 4) 

New vane phaser systems feature an electromagnetic coil situated on the oil control valve, mounted directly on the front of the camshaft. 

Intake Camshafts 

Exhaust cam phasing benefits are reduced emissions and greater fuel economy; however, intake cam phasing provides increased low-end torque and high-end power. (Fig. 5) 

Instead of moving the intake cam to affect overlap in the exhaust stroke, intake closure is delayed at the bottom of the intake stroke. At lower speeds, an open intake valve during the first few degrees of compression can lead to air being pushed back out the intake valve as the piston moves upward. But at higher speeds, the open intake valve allows the air that's been moving into the cylinder to keep coming in under the momentum the air charge has acquired. The result is a cylinder with greater volumetric efficiency. 

Overhead-cam engines that phase both intake and exhaust cams use a vane phaser. Pushrod engines with variable valve timing on their single-cam-in-block engines also use a vane phaser, but these engines differ from overhead-cam engines in that they push the oil control solenoid back into a hollow portion of the front of the camshaft. Four small oil holes are situated in the camshaft to line up with the oil control valve/solenoid. 

It seems that the marketplace is finally ready to be green. When it comes to vehicle air conditioning service, potential customers are looking for service centers that have highly trained technicians and the proper equipment to provide environmentally friendly air conditioning service. 

The Mobile Air Conditioning Society (MACS) Worldwide and the U.S. Environmental Protection Agency have developed the Automotive A/C Climate Protection Pledge to help qualifying service centers be recognized for their environmental leadership in performing proper environmental mobile A/C service. (Fig. 6)

American interest in the environment has grown recently. According to the 2009 Cone Consumer Environmental Survey:

·       35% of Americans have higher interest in the environment today than they did one year ago

·       35% of Americans have higher expectations for companies to make and sell environmentally responsible products and services

·       70% of Americans indicate that they are paying attention to what companies are doing with regard to the environment today 

Service centers completing the Automotive A/C Climate Protection Pledge commit to:

·       Use required tools and equipment

·       Train technicians in Best Practices

·       Promote repairing of leaks and discourage recharge of leaking systems

·       Certify that all contaminated refrigerant collected is sent to a certified reclaimer

·       Set continuous improvement goals

·       Allow EPA to review pledge-related publicity materials (signs, press releases, advertisements, etc.) before they are released

·       Upgrade R/R/R equipment, leak detectors

·       Establish a tool and equipment maintenance program

·       Establish a procedure for removal of refrigerant heels

·       Train service writers or others who greet customers to explain the economic and environmental advantages of having leaks repaired rather than just having the A/C system "topped off" 

Required Equipment 

·       SAE J2788 RRR Equipment

·       Refrigerant Identifier

·       Electronic Leak Detector

·       Ultraviolet Dye Leak Detecting System

·       R134a Manifold Gauges

·       Vacuum Pump (stand-alone or built into R/R/R equipment)

·       Temperature Measuring Devices (digital thermometer, digital pyrometer, infrared thermometer)

·       Hose Repair Crimping Tool (if shop makes own hose assemblies)

·       Spring Lock Coupling Service Tools

·       A/C Fitting Service Tools

·       Orifice Tube Service Tools

·       Service Information Resources (manuals, specification books, computerized information, etc.) 

Technician Training 

All A/C technicians are encouraged to complete a self-study training program focusing on best practices for leak detection, service and repair, and refrigerant conservation. These practices are designed to promote shop savings and efficiency, consumer satisfaction and environmental protection. 

The Best Service Practices Study Course booklet, additional training information, A/C service pledge exam and the pledge application are available on the MACS website at www.macsw.org. 

Take the Pledge 

To take the Climate Protection Pledge 

1.     Go to www.macsw.org and click the Climate Protection Pledge link to download the Best Service Practices Study Course. (All A/C technicians should study this booklet).

2.     Log in to the MACS website to take the Auto A/C Climate Protection Pledge Exam and Pledge. (If you're not a member, log in and create a profile.) There is no charge for the exam. 

Register by Mar. 31, 2010 

Testing on May 6, 11 and 13, 2010 

For more information: 1-888-ASE-TEST (273-8378) 

A customer with a "bad" battery typically expects something to be done about it immediately. The customer may not understand that the battery may be "good" but simply discharged. Customers who want to get back on the road quickly may demand a new battery under warranty. 

There are two things wrong with this approach. First, if the battery is otherwise serviceable, it may only need a recharge to return it to health. Second, unless the cause that discharged the battery is resolved, neither a new battery nor recharging the original battery will solve the real problem. 

The technician's job is to recharge the battery quickly and safely, and determine and repair the cause of the battery becoming discharged. 

Testing a battery using a conductance-type tester can determine if the battery is good and can be recharged. (Fig. 9) 

Charging Ahead 

Battery charging involves applying sufficient voltage to the battery to cause current to flow through the battery. Charging causes a chemical change in both the battery's plates and the electrolyte. If the battery is simply discharged, but otherwise good, applying a suitable current for enough time will eventually fully charge the battery as much as is chemically possible. However, continued application of current can lead to overheating, loss of electrolyte and shortened battery life. 

The charging process requires time and current. Multiply the charging rate in amperes by the number of hours and the result will be the ampere-hours of charge applied to the battery. To bring a battery to full charge will require roughly the same number of ampere-hours at a low charge rate as it does at a high rate. Put another way, a higher rate will take less time. 

Since most customers like to have their vehicles returned quickly, it's desirable to get the charging job done quickly by using a high charge rate. 

State of Charge 

It's not possible to measure a battery's state of charge in ampere-hours, so another method must be used. Open circuit voltage (OCV), measured across the battery's terminals, relates to the battery's state of charge. The voltmeter must be capable of reading to the nearest 0.01 volt. 

If the battery has not been charged or used (the engine started or the vehicle driven) in the last 12 hours, a reading may be taken. 

If the battery has been discharged and recharged or used within the last 12 hours, connect a carbon pile and load the battery at 300 amperes for 15 seconds. Remove the load. Wait 15 seconds and then take the reading. 

The OCV reading is accurate +/- 10%. A battery with a state of charge of 65% or greater is marginally charged enough to be returned to service. However, if the vehicle will be used in slow traffic or short drive times, or in very cold or very hot conditions, the battery should be at least 90% of full charge before returning to service. 

Automatic Battery Chargers 

Advancements in battery charging technology now combine diagnostics and charging control systems that monitor and automatically regulate the charging process. These controls maximize the chargers output based on the battery status, while protecting the battery from overcharge. This means you can use chargers with the highest output ratings, so long as the charger makes the necessary adjustments as the battery approaches full charge. 

Automatic battery chargers such as the Midtronics GR1, Associated Intell/Matic Pro or the Cristie PDQ can return a good, but discharged, battery to at least 85% state of charge in 20 to 40 minutes. (Fig. 10) 

Manual Battery Chargers 

Non-automatic battery chargers do not offer the self-limiting features of the latest equipment. It is the operator's responsibility to control the charging process. 

Monitor both charging current and voltage every 30 minutes. Because voltage is not held constant, it will rise as the battery becomes charged. 

When voltage reaches 16 volts, reduce the charging current to 5 amperes. When the voltage reaches 16 volts again, at the 5 amp current, the battery is fully charged. 

Dead Cold 

A completely discharged battery will take more than twice as long as a half-charged battery to bring the battery to a usable state of charge. The electrolyte in a discharged battery is largely water, which is a poor conductor. The battery may accept such a small amount of current at first that it appears not to take a charge. 

Also, chemical reactions in a battery are slower at low temperatures, so a very cold battery will take longer to charge than one at room temperature. 

AGM Batteries 

The Absorbent Glass Mat (AGM) battery uses absorbent glass mats to hold a small amount of electrolyte in contact with the plates. The battery uses a gas recombinant technology, where the gases produced at the plates are recombined to form water before they escape. This battery design offers high power for lower weight and is more resistant to high temperatures, vibration and cycling. 

The AGM battery may be charged using an automatic battery charger, as long as the charger automatically adjusts the charging current as the battery nears full charge. 

When using a conventional charger, limit the rate to 10 amperes or less. Do not allow the battery to charge at 3 amperes or more for longer than 10 hours, or 10 amperes for longer than 5 hours. When these limits are reached, allow the battery to stand overnight, and then resume charging if further charging is required. 

Check the voltage every 30 minutes and remove the battery from charge when the voltage reaches 15 volts at 3-10 amperes. The state of charge should be at 90-95%. 

Refer to GM bulletin #02-06-03-009C for additional information. 

The ACDelco brand stands for quality. To further enhance that reputation in the remanufactured rotating electrical aftermarket, ACDelco has announced product upgrades to Line 33 Alternators and Starters. 

On many top selling parts in the remanufactured product line, ACDelco will use 100% new regulators on alternators and 100% new solenoids on starters. These product upgrades make ACDelco the only brand using 100% new regulators and solenoids in our most popular remanufactured parts. 

New Quality Label 

The upgraded product will be easy to identify with the addition of a gold quality sticker applied to the top of the box. (Fig. 11)

The upgraded products will be shipped automatically as new orders for alternators and starters are processed. 

Root Cause 

When making repairs on rotating electrical systems, in-depth diagnosis is needed before parts replacement, including checking other components and conditions that might affect system performance, such as any Diagnostic Trouble Codes, battery health and fluid contamination 

Fluid contamination is often the root cause of the failure of starters. For instance, oil intrusion into a starter will degrade the brushes to the point where they will not make good electrical contact with the armature/commutator. Inspect the old starter; if it appears to be oil soaked, repair the source of the leak (i.e. valve covers, intake valley, etc.). Fixing the oil leak will reduce the chance of a customer comeback. 

More Information 

For more information on how to prevent early failures of alternators and starters, check out the Comeback Prevention seminar (S-DS11-01.01SEM). 

To learn more about the latest technology used in modern charging and starting systems, attend the Advanced Charging and Starting Systems Diagnostics seminar (S-EL06-20.01SEM). 

Contact your local ACDelco distributor to learn when a seminar will be held in your area. 

On average, 10,000 people each day visit acdelco.com, the ACDelco consumer website, and about 1,600 of those visitors use the ACDelco locator feature to search for a local TSS service center. That's 1,600 potential customers daily looking for service on their vehicle that your shop may be missing if you're not listed on the ACDelco locator. 

There have been several enhancements implemented recently to the ACDelco locator feature, based on changes made to the TSS program. The following results are provided with each locator search:

•         Bird's eye view capability on the map

•         Locator will show Blue and White Level TSS accounts

•         Blue Level TSS accounts will be highlighted with a white star on the pin

•         The locator will number the identified service centers based on their location to the center of the zip code that has been entered, with the number 1 pin being the closest location. 

Placing the mouse cursor over each pin on the map enables a pop-up of service center/contact information, which includes: (Fig. 12)

•         Service center name

•         Address

•         Phone number

•         Driving directions

•         Listing of services 

ACDelco also provides media support through a number of website and search engines to drive additional traffic to the locator to further encourage potential customers to find and contact the TSS service centers in their local area. 

For more details about the ACDelco locator listings, log in to www.acdelcotechconnect.com, click the Total Service Support tab, and then click the Marketplace link. 

The following technical tips provide repair information about specific conditions on a variety of vehicles. If you have a tough or unusual service repair, the TSS Technical Assistance Hot Line can help. Call 1-800-825-5886, prompt #2, to speak with a technical expert with the latest OEM information. 

Squeak Noise from Rear of Vehicle

1999-2007 Chevrolet Silverado (Classic), GMC Sierra (Classic); 2007-2009 Chevrolet Colorado, Chevrolet Silverado, GMC Canyon, GMC Sierra, HUMMER H3, HUMMER H3T 

A squeak noise may be coming from the rear of the vehicle. During normal operation, certain vehicles may exhibit a squeaking noise that may be traced to the rear leaf springs. While this noise is an operating characteristic of leaf springs, the roads that the vehicle is driven on will affect the frequency and severity of this noise. 

This condition may be due to debris getting between the leaf springs. It has been found that the application of grease to the rear leaf springs will correct this condition and do a better job of preventing the noise from reoccurring than replacement of the springs. 

To grease the springs, pressure wash the springs to remove as much dirt and debris as possible and dry the springs with compressed air. 

Apply a liberal amount of grease under the front and rear tip inserts for the #2 and #3 leaves, on top of the tip inserts, and in between the #1 and #2, and #2 and #3 leaves. 

Periodic cleanings and grease re-application may be necessary throughout the life of the vehicle. 

If this procedure does not correct the noise on 1500 Series (1/2 ton) models built prior to October 2004, the noise may be caused by an incorrectly dimensioned splay clip (the band holding the ends of the leafs together) that interferes with the leaf springs. A 5 mm (0.197 in) wider splay clip was introduced early in the 2005 model year to provide additional clearance. To correct this condition, it may be necessary to replace the rear leaf spring assembly. There was no change to the part number. 

For more information, refer to GM bulletin # 06-03-09-004B. 

OnStar^® Power Consumption 

2000-2010 OnStar-equipped Vehicles with Digital Hardware 

During battery parasitic drain testing, it is important to understand the power cycles of the various OnStar systems in order to avoid confusion about normal power consumption readings. 

All OnStar customers with currently active vehicles have digital/analog cellular capability. A green status LED on the OnStar keypad normally indicates an active OnStar account. (Fig. 13) A red LED indicates a system DTC. On Gen 6 and later systems, a clear or "dark" LED may indicate the OnStar system has been deactivated or may possibly have a no power concern/no communication.

The OnStar system will stay powered up after the ignition is off for an extended time in order to allow for remote services like door unlock, horn chirp, light flash, etc., to take place as requested by the driver. Power cycle times vary depending on the generation of the OnStar system, and may be powered up continuously from 48 hours to 120 hours after the ignition is off. Technicians may identify the system generation by using a scan tool or by using www.onstarenrollment.com. 

The expected current draw of the OnStar module is:

IGN ON - 240 to 400 mA

IGN OFF - 3 to 20 mA for 48 hours

IGN OFF - after 48 hours (120 hours on specified VCPs) - 0.2 to 0.8 mA  

Fluid Flushing Requirements 

2005-2010 Chrysler, Dodge and Jeep vehicles 

Chrysler Group vehicle fluid systems do not require regular flushing. These systems include: engine oil, transmission oil, axle lube, brake fluid, power steering fluid, and refrigerant. The only exception to this requirement are those fluid changes that are published in the vehicle maintenance schedules, e.g. engine coolant, and in instances where a failure has occurred and/or the system has become compromised, contaminated or overheated beyond the normal operating range. 

Aftermarket chemicals to flush the engine, transmission, brake or steering systems are not recommended. Chemicals contained in these products can damage the system elastomeric components, and contaminate the component fluid, leading to loss of system/component durability and service life. When necessary, only the original approved system fluid should be used to flush these components using approved equipment. 

If the engine coolant contains a considerable amount of sediment, clean and flush the system, followed by a thorough rinsing to remove all deposits and chemicals. Refill with a minimum of a 50% mixture of the specified coolant and distilled water. 

How to Take ACDelco Training 

Go to acdelcotechconnect.com and click the Training tab to log in to the ACDelco Learning Management System (LMS). 

·       To enroll in an Instructor-Led Training (ILT) course, click the Enrollment link or the Instructor-Led Courses link. 

·       To launch a Web-Based Training (WBT) course, click the Web-Based Courses link to view the catalog and select a specific course. 

·       To launch a TechAssist (TAS) course, click the TechAssists link to view the catalog and select a specific course. 

·       To launch a Simulation (SIM), click the Simulations link to view the catalog and select a diagnostic challenge simulation. 

New Training 

The following ACDelco training programs have recently been made available via the LMS: 

S-AT02-01.01WBT - Automatic Transmissions

This web-based course provides an introduction to automatic transmissions, including automatic transmission specifications, powerflow through an automatic transmission, the characteristics of automatic transmission cases, the proper operation of torque converters, and the function of automatic transmission gear select indicators. 

S-AT02-02.01WBT - Automatic Transmission Gearset

The characteristics and operation of planetary and differential gearsets are covered in this web-based course. Also reviewed in the course is the disassembly and assembly of gearsets as well as how to service differential gearsets. 

S-AT02-03.01WBT - Automatic Transmission Mechanical Apply Components

This web-based course highlights the mechanical and apply components used in automatic transmissions. Topics covered include operation of the 1-2-3-4 clutch, characteristics of the 3-5 Reverse clutch, operation of the 4-5-6 clutch, characteristics of the 2-6 clutch, operation of the Low and Reverse clutch, and Low clutch sprag characteristics. 

S-AT02-04.01WBT - Automatic Transmission Diagnosis

The processes and procedures for diagnosing automatic transmission concerns are discussed in this web-based course. It discusses the procedure for performing a preliminary inspection, the process for performing a road test, and the procedures used in post-road test diagnosis. 

S-AT02-05.01WBT - Automatic Transmission Hydraulics and Electrical Systems

This web-based course covers the components and operation of the hydraulic system and the electronic controls that drive the hydraulic system, including the functions of the valves located in the fluid pump assembly, the valves located in the control valve body, and the solenoids contained in the solenoid control assembly. The characteristics of the electronic control module, the control module inputs, and the transmission adaptive functions also are reviewed. 

Current Instructor-Led Training 

ACDelco's Instructor-Led Training (ILT) courses provide hands-on instruction on the latest automotive systems. The following ILT courses are currently being held at training center locations around the country. Click the Schedule link on the LMS Menu to search the latest training schedule for courses held in your area. 

S-AC07-02.01ILT

Automotive Air Conditioning: Advanced Refrigerant System Diagnostics 

S-AC07-03.01ILT

HVAC Control System Operation and Diagnostics

S-AC07-06.01ILT

Toyota HVAC

S-AC07-07.01ILT

Chrysler HVAC 

S-BK05-01.01ILT

Braking Systems

S-EL06-04.02ILT

Network Communication Diagnosis

S-EL06-10.02ILT

Electrical Power Management

S-EL06-11.01ILT

Automotive Electrical Circuit Diagnosis and Repair

S-EL06-12.01ILT

Hybrid Technology and Service

S-EP08-02.01ILT

Engine Performance: Computer Controls and Ignition System Diagnostics

S-EP08-03.01ILT

Engine Performance: Air Induction and Fuel System Diagnostics

S-EP08-04.01ILT

Engine Performance: Fault Monitoring and Emission System Diagnostics

S-EP08-05.01ILT

Engine Performance: Advanced Drivability Diagnostics

S-EP08-20.01ILT

Toyota Engine Performance

S-EP08-21.01ILT

Chrysler Engine Performance

S-EP08-81.01ILT

Duramax 6600: Diesel Engine Performance

S-SS04-01.01ILT

Vibration Correction Diagnostics

S-ST10-01.01ILT

Supplemental Restraint Systems