how does the EGR valve fail

ernest · **Joined:** Sat Aug 06, 2016 2:04 pm **Posts:** 21

I bought a mechanics special Jeep 2006 Liberty CRD and drove it from Ohio to California without doing any work on it. Here in California the emissions check is serious. The jeep gives 2 codes of 1) insufficient boost and 2) no EGR flow. I think I can fix the boost problem. However does the EGR valve fail open, or closed, or partially open. If the EGR valve is soaked in oil does that mean it has failed. Thankyou in advance.

mass-hole · **Posted:** Thu Oct 06, 2016 9:02 pm

ernest wrote:

I bought a mechanics special Jeep 2006 Liberty CRD and drove it from Ohio to California without doing any work on it. Here in California the emissions check is serious. The jeep gives 2 codes of 1) insufficient boost and 2) no EGR flow. I think I can fix the boost problem. However does the EGR valve fail open, or closed, or partially open. If the EGR valve is soaked in oil does that mean it has failed. Thankyou in advance.

The ECU determines the EGR flow via the mass airflow sensor over by the air filter. Basically when the EGR opens it looks for the air flow to be reduced through the intake because of the exhaust that is now being recirculated.

The actual EGR flow is controlled by the flow control valve(FCV) which is basically a throttle body that sits on the intake elbow on the drivers side just prior to where the EGR is connected. When it closes, it forces the engine to partially draw from the EGR. Its possible that this could be malfunctioning causing the "egr flow" issue. Really what that code is saying is that you are getting too much clean air flow through the intake. I think the gears that close the flap on the FCV like to shear teeth.

if the FCV has failed shut then i guess it could be causing low boost too since its blocking the path to the intake manifold where the boost sensor is.

Oil on the EGR is something else. The EGR cools the hot exhaust gases with engine coolant but there shouldnt be any oil.

flash7210 · **Posted:** Thu Oct 06, 2016 9:11 pm

The EGR valve will get clogged up with soot. Never fully opening and never fully closing.

My recommendation:
1. Insert block off plates into the egr ports
2. remove the flapper valve from inside the FCV
3. Leave all sensors and things connected and read through the DIY ECM tune thread in the tech section. Get the necessary hardware/software and load the approriate tune for your ECM and delete the codes for egr and fcv.

jws84_02 · **Posted:** Thu Oct 06, 2016 10:07 pm

By chance was this jeep a silver sport?

ernest · **Joined:** Sat Aug 06, 2016 2:04 pm **Posts:** 21

The color is Inferno Red. I read Sam's NOOB guide and learned alot. Thankyou for the responses. This vehicle is amazing.

papaindigo · **Posted:** Fri Oct 07, 2016 8:13 am

The FCV and EGR are two entirely separate "things" although they may interact. The FCV is a "flapper" valve much like the choke plate in an old carburetor and is driven by a plastic gear that can fail leaving the flapper partially closed resulting in low boost due to a restriction in the intake air flow. Easy fix in this case is simple undo the screw(s) holding the flapper in place and throw the flapper away. As far as I know this won't set any codes. EGR is a valve that opens and closes to direct a certain amount exhaust gas back to the intake elbow to be "reburned". There is an EGR cooler but it's primary function is to keep the EGR from overheating due to exhaust flow thru the EGR valve. If gunked up the EGR can fail in a variety of positions but I assume, based on the fault message, yours has failed closed or partially closed. Options a) any of a variety ECU tunes to turn the EGR off, should kill the error code, including free ones or the GDE tune which does lots of other good things (must use a tune if you block the EGR as blocking without a tune will set a code) or b) clean the EGR, see for example viewtopic.php?f=5&t=59352&p=659410#p659410

WWDiesel · **Posted:** Fri Oct 07, 2016 11:15 am

papaindigo wrote:

(must use a tune if you block the EGR as blocking without a tune will set a code)

Not always the case; some have reported blocking their EGR feed tube and it did not set a DTC, while others have stated it did! So I guess it is not true 100% of the time?
I have no idea why some will set a code and then some do not! :shock:

I know I blocked off the EGR feed tube and ran that way for well over 6 months and only got about 2 DTC's relating to the EGR over the entire period before installing the Weeks elbow kit and re-flashing the ECM...

I did remove the butterfly plate out of the FCV at the same time when I blanked off the EGR feed tube; so I do not know if this makes a difference as related to setting a code or not?

mass-hole · **Posted:** Fri Oct 07, 2016 12:43 pm

WWDiesel wrote: