AfterMarketNews Brake&Frontend BodyShopBusiness Counterman EngineBuilder Fleet Equipment ImportCar Motorcycle & Powersports News Servicio Automotriz Shop Owner Tire Review Tech Shop Tomorrow's Tech Underhood Service Speedville

Honda Civic: Failed PCMs And CAN System Diagnostics

It’s not unusual for me to get help requests through my e-mail. Sometimes it’s from working technicians, other times it’s from vehicle owners who can’t get their problems solved through professional repair shops. In early 2014, I received one...

Read more...

Servicing Mercedes-Benz AIRMATIC Suspensions

The Mercedes-Benz AIRMATIC suspension system was introduced in 1999 on the S-Class and has subsequently been used on the E-Class and most of the automaker’s SUVs. The system employs electronically controlled air springs that provide an ideal balance...

Read more...

Mazda: Performing Regular Undercar Maintenance

In this article, we’ll take a look at brake and undercar service on the Mazda vehicle lineup, with the footnote that even though this type of work ­becomes routine when you have a preventive maintenance mindset, good work habits from beginning to end...

Read more...

GM Power Steering Noise/Leaks

GM: Power Steering Noise/Leaks from Power Steering Pump, Gear or High Pressure Hose During Extreme Low Temperature Conditions MODELS: -2009-2015 Buick LaCrosse (Equipped with Hydraulic Power Steering) -2010-2013 Buick Regal -2012-2015 Buick...

Read more...

Ford Edge Brake Replacement

Ford Edge Brake Replacement Basics The Ford Edge is an SUV based on the CD3 platform. The brakes on these vehicles are straightforward and do not break any new ground. There were no major changes to the brake systems from 2007 to the current model. For...

Read more...

Live-Axle Wheel Bearing Replacement

Replacing wheel bearings on a vehicle with a live rear axle may not be one of the most frequent jobs, but it can be one of the most profitable. While the basics have not changed in more than 60 years, new seal materials and differential designs have...

Read more...

The Ins And Outs Of Sanders

Sanders are required tools in today’s collision repair shop. Body techs and painters rely upon them every day to achieve that perfect finish on your customers’ vehicles. Whether you’re prepping a panel for paint or removing imperfections before...

Read more...

Are You Regularly Maintaining Your Equipment?

Technicians who are idling because the welder won’t feed wire, the hydraulic ram won’t pull chains, the booth heater won’t heat or the air compressor won’t compress enough air is a costly mistake, as labor time is the most expensive thing in any...

Read more...

Celebrate 'Back To The Future' Day By Watching The Time Machine Get A 2015 Detail

    For many today is just another Wednesday, but for a lot of people it is more than just your average Wednesday, it is "Back to the Future" Day. It is a day that everyone who watched the cult classic trilogy Back to the Future recognizes...

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.

 

Latest articles from our other sites:

GF-6 Oil Specification: What It Means For Your Shop

The Obama Administration finalized fuel economy standards in 2012 designed to increase fuel efficiency standards to 54.5 mpg for passenger cars and light-truck applications by 2025. This push for greater...More

Hunter's Quick Check And Quick Tread Fully Integrated With AutoServe1

Hunter Engineering’s Quick Check and Quick Tread now fully integrate with the AutoServe1 digital vehicle inspection and customer communication system. According to AutoServe1, its product is one of...More

LTI Tools Offers Universal Wheel Bearing Hub Removal Tool

Safely remove all frozen hubs instantly with LTI Tools’ Universal Hub Shocker Wheel Bearing Hub Removal Tool (LT830A). It’s universal fit mounts to all axle bolted hubs – 5-, 6- and 8-lug...More

TrakMotive Introduces New Replacement Intermediate Shafts

Trakmotive has announced the release of two new intermediate shafts to complement the company’s axle program. These units are currently in stock and ready to ship. TrakMotive recommends replacing...More

Plews & Edelmann Couplers Provide More Flow, More Power in Less Time

Tru-Flate HI FLO couplers and plugs provide twice the airflow of a standard coupler and plug, up to 70 cfm @ 90 psi, ensuring your tools will provide maximum torque and optimal performance. They...More

LTI Tools Offers Universal Wheel Bearing Hub Removal Tool

Safely remove all frozen hubs instantly with LTI Tools’ Universal Hub Shocker Wheel Bearing Hub Removal Tool (LT830A). It's universal fit mounts to all axle bolted hubs – 5, 6 and 8 lug hubs. And...More