What's the best method you have used?
Thanks in advance.
Thanks in advance.
How to clean EGR Valve
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jvmagic
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(Source Jrichker @ Stangnet)
Recommended procedure for cleaning the EGR:
Conventional cleaning methods like throttle body cleaner aren’t very effective. The best method is a soak type cleaner used for carburetors. If you are into fixing motorcycles, jet skis, snowmobiles or anything else with a small carburetor, you probably have used the one gallon soak cleaners like Gunk or Berryman. One of the two should be available at your local auto parts store for $22-$29. There is a basket to set the parts in while they are soaking. Soak the metal body in the carb cleaner overnight. Don’t immerse the diaphragm side, since the carb cleaner may damage the diaphragm. If you get any of the carb cleaner on the diaphragm, rinse it off with water immediately. Rinse the part off with water and blow it dry with compressed air. Once it has dried, try blowing through the either hole and it should block the air flow. Do not put parts with water on them or in them in the carb cleaner. If you do, it will weaken the carb cleaner and it won’t clean as effectively.
** Gunk Dip type carb & parts soaker **

If you have a handy vacuum source, apply it to the diaphragm and watch to see if the pintle moves freely. Try blowing air through either side and make sure it flows when the pintle retracts and blocks when the pintle is seated. If it does not, replace the EGR.
If you suspect the egr system of causing an idle or driveability issue,do the following:
Remove the vacuum hose from the egr valve,plug the hose then take the car for a test drive.This will cause the ecm to delete egr function.Ignore any check engine light during this time.If the idle or driveability issue disappears once the vacuum hose in removed and plugged,thats an indication something is wrong with an egr system component.The valve,evp sensor,evr solenoid and hoses make up the egr system.
The rubber diaphragm portion of the egr valve can develop pinhole size leaks in it causing a vacuum leak and lean condition,but the most common problem is a carbon clogged valve that keeps the egr valve open 100% of the time.Its only suppose to be open during cruise conditions.
Recommended procedure for cleaning the EGR:
Conventional cleaning methods like throttle body cleaner aren’t very effective. The best method is a soak type cleaner used for carburetors. If you are into fixing motorcycles, jet skis, snowmobiles or anything else with a small carburetor, you probably have used the one gallon soak cleaners like Gunk or Berryman. One of the two should be available at your local auto parts store for $22-$29. There is a basket to set the parts in while they are soaking. Soak the metal body in the carb cleaner overnight. Don’t immerse the diaphragm side, since the carb cleaner may damage the diaphragm. If you get any of the carb cleaner on the diaphragm, rinse it off with water immediately. Rinse the part off with water and blow it dry with compressed air. Once it has dried, try blowing through the either hole and it should block the air flow. Do not put parts with water on them or in them in the carb cleaner. If you do, it will weaken the carb cleaner and it won’t clean as effectively.
** Gunk Dip type carb & parts soaker **

If you have a handy vacuum source, apply it to the diaphragm and watch to see if the pintle moves freely. Try blowing air through either side and make sure it flows when the pintle retracts and blocks when the pintle is seated. If it does not, replace the EGR.
If you suspect the egr system of causing an idle or driveability issue,do the following:
Remove the vacuum hose from the egr valve,plug the hose then take the car for a test drive.This will cause the ecm to delete egr function.Ignore any check engine light during this time.If the idle or driveability issue disappears once the vacuum hose in removed and plugged,thats an indication something is wrong with an egr system component.The valve,evp sensor,evr solenoid and hoses make up the egr system.
The rubber diaphragm portion of the egr valve can develop pinhole size leaks in it causing a vacuum leak and lean condition,but the most common problem is a carbon clogged valve that keeps the egr valve open 100% of the time.Its only suppose to be open during cruise conditions.
I tested the EGR valve at an auto parts store and the EGR did not hold any pressure (see video link below). Will cleaning the EGR valve help with this or does it need to be replaced?
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Its not gonna hold any vacuum without the evp sensor/gasket being bolted to it.Thats the reason why theres a gasket mounted between the evp sensor and egr valve.If you view the picture below,you can see the whole area where vacuum will be present inside the egr valve diaphragm housing.Mount the evp sensor & its gasket to the egr valve then try your test again.The main things that cause egr malfunction are:
1) carbon buildup between the pintle valve and seat,which prevents the valve from closing completely
2) pinhole leak in the diaphragm,which prevents the valve from opening because vacuum wont hold to pull the valve open
3) carbon buildup thats so hardened that it cant be removed
4) egr valve is stuck open/closed due to a defective evr solenoid
5) evp sensor is defective
The following link details how to thoroughly test the egr components.
EGR/EVP Codes 31/32/33/34/35 Troubleshooting
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Thanks for the detailed response. I based my results from the below video. I assumed all EGR valves should behave the same. I don't recall a gasket between the EVP sensor and EGR.
- Reaction score
- 536
- Location
- Nashville
Check out the pictures below.You can see the evp sensor and gasket.In the video in your last post,it shows an egr valve that doesnt use a evp sensor,but the egr valve on a 86-93 5.0 Mustang does use an evp sensor.The evp sensor & gasket is what seals off the vacuum chamber,so if the gasket was leaking or the sensor and gasket are totally missing,like they are in the video where you tested the valve at the parts store,that will keep the egr valve from holding vacuum since youve got a big open hole there.The egr valve in the video in post #5 doesnt have an evp sensor attached to it that seals off the vacuum chamber,so thats why their test is working like it should,but yours is not.If you place the palm of your hand completely over that hole where the evp sensor normally sits and use the vacuum pump to apply vacuum to the egr valve,that might seal it up enough to test whether your valve holds vacuum or not,but it only takes 30 seconds to mount your original evp sensor to the valve.
Attachments
I connected everything back up, plugged the hand vacuum, started the car, at idle I added pressure, the car idled a bit rougher, and the EGR held the pressure. Sounds like the EGR valve is good. Should the next step be disconnect the EGR valve and drive the car as you stated before? If not, what else?
The reason for this is the code and the EVAP fail test (CA smog).
Thanks again!
- Reaction score
- 536
- Location
- Nashville
Eventhough theyre all part of the emissions system,the egr system,thermactor system & evap system are all seperate working systems.IOW- if you get a code for the evap system,the egr & thermactor components shouldnt be the cause for the evap code.
BTW- what codes are you getting??
31,32,33,34,35 are egr codes
85 is the purge valve
The following shows the list of evap components on a Foxbody and the diagram at the bottom shows the arrangement of those components:
1) gas cap
2) rollover/vent valve on top of the gas yank
3) vacuum hose that runs from the rollover valve to the carbon canister
4) carbon canister
5) vacuum hose from canister to purge valve
6) purge valve
7) vacuum hose from the purge valve to the upper intake
The main causes of an evap code are dry rotted hoses (causing a vacuum leak) or a defective purge valve.
Yeah it sounds like your egr valve is working correctly.The egr valve is opened by the ecm grounding the evr solenoid.The egr valve is only suppose to open during cruise conditions,so if its opening at idle,during acceleration/deceleration or at wot,the evr solenoid is most likely bad.The evp sensor tells the computer how far open the egr valve is.If youre having a driveability issue,you can remove the egr valve vacuum hose & plug it then test drive it and if the issue goes away,that indicates an egr component is faulty.You can trigger the evr solenoid to open the egr valve by piercing the solenoids Dk Green or Brown/Pink wire with a needle,starting the engine and letting it idle then touch the needle to a good ground and you should see the egr valve open everytime you ground that wire.Check the vacuum hose routing to the solenoid also.
The bottom port should have a hose running from the port to the upper intake vacuum fitting.
The top port (closest port to the wiring harness plug) should have a hose running from the port to the egr valve. If the hoses are on the wrong port,the egr valve will stay open all the time.
BTW- what codes are you getting??
31,32,33,34,35 are egr codes
85 is the purge valve
The following shows the list of evap components on a Foxbody and the diagram at the bottom shows the arrangement of those components:
1) gas cap
2) rollover/vent valve on top of the gas yank
3) vacuum hose that runs from the rollover valve to the carbon canister
4) carbon canister
5) vacuum hose from canister to purge valve
6) purge valve
7) vacuum hose from the purge valve to the upper intake
The main causes of an evap code are dry rotted hoses (causing a vacuum leak) or a defective purge valve.
Yeah it sounds like your egr valve is working correctly.The egr valve is opened by the ecm grounding the evr solenoid.The egr valve is only suppose to open during cruise conditions,so if its opening at idle,during acceleration/deceleration or at wot,the evr solenoid is most likely bad.The evp sensor tells the computer how far open the egr valve is.If youre having a driveability issue,you can remove the egr valve vacuum hose & plug it then test drive it and if the issue goes away,that indicates an egr component is faulty.You can trigger the evr solenoid to open the egr valve by piercing the solenoids Dk Green or Brown/Pink wire with a needle,starting the engine and letting it idle then touch the needle to a good ground and you should see the egr valve open everytime you ground that wire.Check the vacuum hose routing to the solenoid also.
The bottom port should have a hose running from the port to the upper intake vacuum fitting.
The top port (closest port to the wiring harness plug) should have a hose running from the port to the egr valve. If the hoses are on the wrong port,the egr valve will stay open all the time.
Attachments
The only code spitting out is 33. The car initially failed smog due to high NOX but it passed the EVAP test. The fuel pump was failing as well so I replaced the fuel pump. Upon the next smog check, the NOX was a bit better (barely failed) but this time around it failed the EVAP test. So here I am trying to figure out with your help. Also, there is a gas smell (is that what running rich is?) coming out of the exhaust pipes (most of the time)at idle.
I'll check the hose routing today and drive as you stated above.
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- Nashville
Most of the time,vacuum leaks are the biggest cause for the car running too rich.When a vacuum leak is present,it allows air (which didnt get metered by the maf sensor) to enter the exhaust system which then gets measured by the o2 sensors.The o2 sensors see this extra air and their reading triggers a lean condition.The ecm sees the lean voltage signal and begins (falsely) adding fuel to try and compensate.If you let the engine idle then connect a 1-2' piece of hose to a small handheld propane torch and trace the hose around vacuum hoses,gaskets,vacuum fittings,vacuum operated solenoids,etc,youll hear the engine idle surge upwards if you cross over a vacuum leak.The propane will be drawn into the leak.I like to lay a wet towel down over the areas close to where Im checking,just for safety reasons.
A dirty maf sensor can cause overly rich conditions too.Get some CRC MAF cleaner and clean the sensors heated wires very carefully.Let air dry before reinstalling.
Code 33 usually means the evr solenoid isnt working,has a leaking/disconnected/incorrectly routed vacuum hose or the evp sensor is faulty.Make sure the hose leading from the intake is connected to the bottom evr solenoid port and the hose from the egr valve is connected to the top port.Start the car and use a jumper wire to ground the evr solenoid Dk Green wire to a good ground or the neg battery post.The egr valve should open.If not,make sure the evr solenoid red wire shows 12 volts.If it does,the evr solenoid is bad.
With the koeo,touch the red multimeter lead to the orange/white wire and the black lead to the black/white wire on the evp sensor.It should measure close to 5.0 volts.Now touch the red meter lead to the brown/lt green wire and the black lead to the black/white wire.It should read 0.25-0.67 volts.If it doesnt,the evp sensor is bad.
A dirty maf sensor can cause overly rich conditions too.Get some CRC MAF cleaner and clean the sensors heated wires very carefully.Let air dry before reinstalling.
Code 33 usually means the evr solenoid isnt working,has a leaking/disconnected/incorrectly routed vacuum hose or the evp sensor is faulty.Make sure the hose leading from the intake is connected to the bottom evr solenoid port and the hose from the egr valve is connected to the top port.Start the car and use a jumper wire to ground the evr solenoid Dk Green wire to a good ground or the neg battery post.The egr valve should open.If not,make sure the evr solenoid red wire shows 12 volts.If it does,the evr solenoid is bad.
With the koeo,touch the red multimeter lead to the orange/white wire and the black lead to the black/white wire on the evp sensor.It should measure close to 5.0 volts.Now touch the red meter lead to the brown/lt green wire and the black lead to the black/white wire.It should read 0.25-0.67 volts.If it doesnt,the evp sensor is bad.
The EVR solenoid had a broken vacuum line (green). I've replaced it and will disconnect the battery/drive a few times to see if the code went away.
Next is to figure out why the car failed the EVAP test.
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