AfterMarketNews Auto Care Pro AutoProJobs Auto-Video.com Brake&Frontend BodyShopBusiness Counterman EngineBuilder Fleet Equipment ImportCar Motorcycle & Powersports News Servicio Automotriz Shop Owner Tire Review Tech Shop Tomorrow's Tech Underhood Service

Do Training, Technology And Parts Sourcing Issues Keep You Up At Night?

We often hear that the things that keep shop owners awake at night pertain to profitability, productivity, training, keeping up with technology, shop operations/expenses and parts quality/availability. This month, we hear directly from one of your...

Read more...

Top 10 Automotive Repair Shop Pet Peeves

No two days are the same for the owner of a repair shop. Every day brings its unique set of challenges to overcome, but, for the most part, the day progresses along and one day passes to the next. But, there are those occasions when certain daily activities...

Read more...

Keeping Counterfeit Parts Off The Road

One constant refrain in the technical features on AutoCarePro and all of our sister sites, is the need to use quality parts — and trust where that part is coming from. Failing to do so puts your customer and your shop’s reputation at risk. But...

Read more...

Engine Coolant Temperature Diagnostics

While old-school cooling system service often ­focused on coolant leaks and overheating engines, let’s begin thinking “new-school” by looking at modern cooling systems through the eyes of the engine coolant temperature (ECT) sensor. Coolant temperature...

Read more...

Volkswagen: Parking Indicator Sounds Off with No Obstacle

Customer complains that the parking assistance issues warning sounds for both the front and/or rear of vehicle with no obstacle in range. Water intrusion into sensor holders is causing corroded plug contacts and sensor electrical pins, which results in...

Read more...

Volkswagen: Unnecessary Electric Coolant Fan Replacements

Model: 2006 Volkswagen Jetta Sedan Customer concerns of “electric coolant fans continue to run after the ignition is switched off” are resulting in unnecessary coolant fan replacements. It is considered normal operation for the electric coolant...

Read more...

Ford Fusion Alignment Spec (2005-‘13)

Millions of Ford ­Fusions were sold in the U.S. between 2005 and 2013. When it comes to alignments, it is critical to diagnose the customer first, to find out if their Fusion drifts or pulls, and then to check all of the possibilities for the complaint...

Read more...

Nissan Titan Brake Job

The Titan is Nissan’s full-size pickup. The Titan has had no major brake problems or recalls, and the brakes are fairly easy to service. Nissan had a few teething problems with brake judder on 2004-‘06 models, but this was corrected with better...

Read more...

The Case for On-Car Wheel Balancing and Wheel-to-Hub Indexing

Off-car wheel balancers do an excellent job of measuring dynamic unbalance — static and couple — and many also measure tire/wheel uniformity, radial runout or calculate radial force variation (RFV) to help eliminate vibration and verify the assembly...

Read more...

Educating Drivers, Technicians and Service Advisers with Dill’s New TPMS Videos

Dill Air Controls has launched its new TPMS training and educational videos, supporting three audiences — consumers, technicians and service advisers. The consumer videos are available in shortened versions, and are positioned for the customer waiting...

Read more...

Top 5 Tools: Kenny Younkins, Ken’s Auto Service Center

Kenny Younkins, owner Ken’s Auto Service Center Akron, OH While Ken first said his favorite tool is his fishing rod, he said in the shop he prefers these five:   Snap-on 3/8” Drive Impact Wrench Mastercool Brake Flaring Kit Mitchell...

Read more...

Mitchell 1 Enhances Quick Links and Printing Functions in Latest Release of ProDemand

Mitchell 1 announces it has made several important enhancements in the latest release of its ProDemand repair, diagnostic and maintenance information program as a direct response to customer feedback. The implemented changes include an expanded Quick...

Read more...

Home Emissions Tech Feature: Diagnosing Ford Exhaust Gas Recirculation System Problems

Print Print Email Email

By Steve Miele, Ford Accelerated Credential Training (FACT) instructor,
Universal Technical Institute

To diagnose and repair Ford exhaust gas recirculation (EGR) systems properly, it is important to understand how they work and what is unique to the product line.

Ford EGR systems are designed to reduce smog-causing nitrous oxides (NOx) by recirculating a portion of the exhaust gases from each cylinder of the engine back into the intake manifold. This process lowers the combustion temperature to under 2,500° F, above which NOx gases are formed, hurting both the environment and a vehicle’s performance.

Typically, the Ford EGR system doesn’t require regular maintenance, but a valve that is clogged or sticks could result with the check engine light turning on, decrease in gas mileage, a vehicle that idles roughly or fails the next emissions test. Then what?

Ford EGR Systems
Late-model EGR systems are a differential pressure feedback system (DPFE) regulated by a power control module (PCM). The system is composed of a DPFE sensor, EGR vacuum regulator ­solenoid, EGR valve and assorted hoses. 

The EGR valve is interposed between the engine exhaust and intake manifold. EGR flow is controlled by the engine’s computer, which opens and closes the EGR valve as needed.

When the system is functioning correctly, it precisely controls the flow of ­recirculated exhaust and helps reduce detonation under certain driving conditions by using its valve to control the flow of exhaust gases into the intake manifold. Since exhaust gases are inert when introduced into the cylinders, oxygen is displaced and causes the PCM to reduce fuel-limiting combustion temperatures. The gases also absorb heat.

Ford uses both vacuum-actuated and electrical EGR systems to recirculate exhaust gases. Ford’s vacuum-actuated EGR systems are the most common and work with the majority of gas engine applications. The electrical EGR systems are used in some four-cylinder and Ford diesel-powered vehicles.

Both these systems use an EGR vacuum regulator (EGRVR) duty-cycle solenoid to apply vacuum to the valve and a DPFE to monitor the flow rate.

There is a vacuum line coming off the intake manifold to the EGRVR actuator, an electric device controlled by the PCM that regulates how much vacuum is necessary. From there, another hose connects to the EGR valve, allowing exhaust gases to be pulled from the exhaust manifold, past the DPFE tubes, then back into the intake manifold.

The DPFE registers the amount of pressure differential across the orifice and tells the PCM how much exhaust gas is flowing through the EGR system. The PCM uses this report to control the actuator.

System Designs
The two Ford vacuum-actuated EGR systems are as follows:
Differential pressure feedback (DPFE) EGR system — The orifice is located in the EGR tube.
Electronic system module (ESM)EGR system — The orifice is incorporated into the EGR valve gasket.

The two Ford electric EGR systems include the following:
Stepper motor valve — A temperature manifold absolute pressure (TMAP) sensor is used to monitor flow rate. This is used in some four-cylinder Fords.
Duty-cycle solenoid valve — The EGR position sensor and the intake air temperature sensors (IAT 1 and IAT 2) are used to monitor the flow rate. This is seen in Ford diesel vehicles.

Unique to Ford
The DPFE sensor is unique to Ford because it actually measures the flow of the exhaust gases. It is a pressure transducer that measures the pressure differential across an orifice in the EGR tube that runs from the exhaust manifold to the EGR value. This is an extremely accurate way to measure the actual flow of the exhaust gases. Instead of a calculated or inferred value, it is a measured value. The DPFE sensor used in the ESM system measures the exhaust side pressure, and the MAP portion of the sensor measures intake manifold side pressures. The ESM system incorporates the EGR valve, EVR solenoid and the DPFE/MAP sensor into one unit.

Diagnosing Problems
Potential problems could involve the flow of gases — when there is either not enough or too much in the system. Restricted flow can result in high NOx emissions and detonation (engine knock or ping) under certain driving conditions. Too much gas flow can result in rough idle stalling, as well as surging.

EGR valve problems can range from inoperative to sticking valves. There can also be PCM input or circuit issues. Sometimes the DPFE sensor becomes dysfunctional due to heat and moisture in the exhaust. The EVR solenoid vent or vent filter can become clogged, causing excessive EGR flow. Other problems can occur due to a blockage in the EGR passages due to carbon buildup.

The diagnostics associated with any of these potential problems should cover the symptom, system, its components and cause. Determining why the problem happened is perhaps the most important part of any diagnosis in order to minimize the possibility of any repeat failures. If EGR problems are ignored or not diagnosed correctly, the result can be high NOx emissions into the environment.

Engines that do not have detonation sensors to adjust the timing could have excessive detonation problems, possibly resulting in engine damage.

It may seem very basic when identifying the symptoms for EGR system failure, but always verify the concern and perform a visual inspection.

A “flow at idle test” is an excellent way to determine if the EGR system is the cause of a rough idle or stalling concern.

This test compares the DPFE Parameter Identification (PID) value — key-on-engine-off (KOEO) and key-on-engine-running (KOER) at idle. Both values should be the same.

More variation than 0.15 volts indicates EGR flow at idle. It is always important to reset any codes that may have been changed during testing.

There are a number of component tests to diagnose issues in the DPFE sensor, EGR valve control solenoid and the EGR value. These tests involve having access to a number of tools. 

You may need a digital volt/ohm meter, hand vacuum pumps, test probes, scanners, appropriate test procedures and wiring diagrams.

The total replacement of an EGR component is generally an easy repair. On the other hand, carbon-filled, restricted or clogged intake passages along with wiring problems can take much more time. A trained technician can do both expeditiously.  

About the Author
STEVE MIELE began his career in automotive repair working at his uncle’s repair shop while finishing high school. He attended college and worked full-time as an automotive technician. In 1982, Miele opened his own independent repair shop. In 1998, he sold his interest in the business and began teaching at Universal Technical Institute’s (UTI) Avondale, AZ, campus, where he continues to train students to become automotive technicians. He joined the Ford Accelerated Credential Training (FACT) program at UTI Avondale in 2001.

Photos
Photos courtesy of Universal Technical Institute (UTI), a provider of technical education training for students seeking careers as professional automotive, diesel, collision repair, motorcycle and marine technicians. The company offers undergraduate degree, diploma and certificate programs at 10 campuses across the United States, and manufacturer-specific training programs sponsored by the manufacturer or dealer at dedicated training centers. For more information, visit www.uti.edu/news.

 

The following two tabs change content below.
Underhood Service Staff Writers

Underhood Service Staff Writers

Underhood Service Staff Writers

Latest posts by Underhood Service Staff Writers (see all)

Latest articles from our other sites:

Streamlight Launches Compact ProTac 1AAA Light


Streamlight Inc. has introduced the ultra-lightweight ProTac 1AAA, the latest addition to the ProTac series of tactical handheld lights. The new light uses one easily sourced AAA alkaline battery, and...More

Ingersoll Rand Adds Small Rotary Compressors to R-Series Line

Ingersoll Rand extends its R-Series line of compressed air solutions to include small rotary compressors with V-Shield technology to reduce leaks and improve reliability. Built on a common platform,...More

Engine Coolant Temperature Diagnostics

While old-school cooling system service often ­focused on coolant leaks and overheating engines, let’s begin thinking “new-school” by looking at modern cooling systems through the eyes of the engine...More

Volkswagen: Parking Indicator Sounds Off with No Obstacle

Customer complains that the parking assistance issues warning sounds for both the front and/or rear of vehicle with no obstacle in range. Water intrusion into sensor holders is causing corroded plug contacts...More

Diagnostic Strategies For Solving TPMS Errors

The first step in any diagnostic strategy is to figure out whether or not your customer's vehicle actually has a TPMS problem. Any number of things can cause the TPMS warning light to come on or flash....More

Ford Fusion Alignment Spec (2005-‘13)

Millions of Ford ­Fusions were sold in the U.S. between 2005 and 2013. When it comes to alignments, it is critical to diagnose the customer first, to find out if their Fusion drifts or pulls, and...More

Streamlight Launches Compact ProTac 1AAA Light


Streamlight Inc. has introduced the ultra-lightweight ProTac 1AAA, the latest addition to the ProTac series of tactical handheld lights. The new light uses one easily sourced AAA alkaline battery, and...More

Millermatic 190 and 141 MIG Welders Offer Improved Ease-of-Use and Arc Performance

The new MIG and Flux-Cored-capable Millermatic 190 and Millermatic 141 MIG welders (replacing the Millermatic 180 Auto-Set and Millermatic 140 Auto-Set MIG welder models) offer users improved portability,...More