Another EGR valve question?

Question

How do you know if you need a new EGR valve or if you just need to clean it?

Answer 1

Exhaust gas recirculation (EGR) valves are usually vacuum operated. Assuming this is the case with your car I offer this explanation that might assist you in determining if it needs to be cleaned or replaced.

Either the EGR system is inoperative or it works too well. If its inop, this means it does not open as designed resulting in insufficient flow. The complaint is usually engine "pinging" or failing an emissions inspection. An inoperative EGR system can be the valve itself or the intake and/or exhaust ports the valve is attached to. Determining if the ports are clogged can be accomplished by removing the valve and inspecting the ports visually or by sound. Clogged ports will likely look clogged with a soft or hard tar like substance called carbon. The carbon build-up might be in the ports and/or on the underside of the valve. Occassionally, the ports look clean, but are clogged downstream. To determine this, start the vehicle with the valve removed. One port is the exhaust and if clear, will make a loud exhaust noise (explosions). The other port is the intake port and if clear will make a loud sucking noise. Another way an EGR system can be inoperative is if the valve diaphragm is ruptured (ripped or torn). A ruptured diaphragm will not allow vacuum to build-up to sufficient levels to lift the EGR pintle away from its seat. This can be diagnosed with the use of a hand vacuum pump. If applying vacuum using a hand vacuum pump does not result in building vacuum and lifting the pintle, the vacuum diaphragm COULD be ruptured. I say could because some systems use back pressure EGR valves. These systems require special test procedures that I don't have in front of me right now. One more reason an EGR system could be inop is due to the pintle be seized. This is the case when the valve holds vacuum, but there is no pintle movement. If you're lucky this can be remedied with some penetrating oil and pliers.

Believe it or not, an EGR system can work too well. The complaint in this case is usually hesitation and/or stumble on acceleration or maybe surging at cruise speed. This can be the result of excessive vacuum, but more often than not is due to a weak return spring. When the spring inside the EGR valve gets hot and cold many times over the years, the spring gets weak. Weak spriings allow the diaphragm to lift the pintle off it's seat too fast and/or too far resulting in excessive EGR flow, hence the hesitation and/or surge.

One more way an EGR system can fail is by sticking open. The complaint is usually a rough idle or stalling at idle. This is usually caused by a piece of carbon getting stuck between the pintle and seat.

If you determine the EGR system is clogged with carbon, then cleaning usually is the answer. Carburetor cleaner can be effective. Clogged ports sometimes requires a "roto-rooter" approach. A "snake" can be made from a speedometer cable and a reversible drill. Fray the end of a universal speedo cable available from most part stores and attach the other end to the chuck of a reversible drill. Run the apparatus through the ports to clear the clog. A small pick tool can be used to clear stuck carbon from a pintle and seat.

Ruptured diaphragms, weak springs and damaged pintle and/or seats require replacement of the EGR valve. I recommend an original equipment manufacturer (OEM) replacement part. The cost more, but more often than not, outperform aftermarket parts. FYI.

Answer 2

Usually it the car runs like crap at idle and beautifully any other time and you can't clean the EGR but cleaning the port in the intake sometimes helps for a check engine light with no running problems

But as others said, the EGR is usually monitored with a sensor on or near the valve and the parts houses that do the free scans have a habit of convincing you the part they can sell you will fix it when usually it won't...

Take it to a real mechanic shop, let them diag it for you

Answer 3

You obviously had a parts store diagnosis so maybe you should ask the person that put the idea in your head that the EGR was a problem for the answer. Did you know that an EGR code can be caused by numerous other problems.

Answer 4

Take the car to a dealership (Ford, if you have a ford, etc.) This could save you being ripped off by a shade tree operation. Believe it or not, lol, there are some crooks out there!

Answer 5

Bring it to the dealer, they will take it apart and find out whether it's just clogged or broken or something else - like for example, DPFE sensor on Fords

Answer 6

Check with the dealership. A lot of models have had them recalled so it may not cost you anything to have it replaced!