EGR Valve Solenoid?

[blu02expy]

I have a 4.6 XLT Expedition and I have been having an EGR problem for a while now. In the beginning I was getting the check engine light and bucking so I had the value cleaned and the sensor replaced. After about a month the light came back on so I just replaced the EGR with one from AutoZone. Since doing that I have still having the same issues but now have a whistling (sp?) noise coming from the EGR. The other day my brother-in-law looked at it and said he thinks it has something to do with the green tube that runs from the top of the EGR to the egr valve solenoid because it is barely sucking air while the red tube that runs from the solenoid has a strong suction. My question is..... Is there suppose to be a strong suction coming out the EGR value (green tube) to the egr valve solenoid. Has anybody else has this problem and fixed the problem by replacing the solenoid?

Thanks in advance...

 

[blu02expy]

Forgot.... It's a 2002 with 78K miles

 

[mustangswan]

The green is for vaccum to the egr valve from the solenoid and should have vacuum only when the vavle is being actuated. The red line is manifold vacuum and should have 18-20 in-hg at idle. A common problem on the 4.6/5.4l is that the egr port in the elbow between the throttle body and the intake manifold gets clogged with carbon. This will give you a check engine and most of the times the code is a P0401. If you remove the neck it will easy to see if it is full of carbon, use a long pick and throttle body cleaner. You will also need to replace the gasket at the base and at the egr valve.
Hope this is helpful.

 

[blu02expy]

Thanks....Silly question but where is the egr port located? Do have have to take the egr value off again to get to it?

 

[mustangswan]

The port is in the elbow that the throttle body is mounted to and also that the egr vavle is mounted to. I would recommend that the elbow be removed for cleaning because large pieces of carbon would go in to the intake and could get stuck on a valve. There is also a chance that the DPFE sensor could be causing the light.

 

[blu02expy]

Alright I ended up taking the entire throttle body off. As soon as I did I saw two pieces of black crust (cardon) sticking completely out of two little wholes which were at the base of the EGR port. Took two bottles of Carb cleaner and a lot of scraping to get them clean. Went ahead and cleaned the inside of the throttle body also. Hopefully that fixes the CEL, if not DPFE is next I guess.

Thanks mustang!!!

 

[blu02expy]

Man this problem sucks, my CEL came back on. I have cleaned the upper intake completely out, installed a new EGR, new EGR vac solenoid, my dad's friend (ford mechanic) the dpfe on a few months back and I am still getting the low flow code for the EGR. Whatelse could it be? I called myself trying to save money buy doing it myself instead of taking to the dealer. I am going to seaform my truck today....could that be the problem? My symptoms are still the bucking while driving, hesitation/"spudder" at take off, and a feeling that the truck is struggling to get air, gas, or something. I put 1/2 a can of seafoam in the gas tank yesterday (tank was a little below half full). Could my engine just be so dirty that is throws the low egr flow code? Could a dirty lower intake be the problem? Being the DPFE was replaced back in Jan/Feb could it have gone bad again just based on how dirty my egr ports were before I cleaned then? If everything else was good and clean expect DPFE would that alone cause my symptoms or would I just have a CEL?

I am truly at a loss now.

 

[mustangswan]

Sorry to hear that the clogged ports did not fix the entire problem, but if they were full, they needed to be cleaned. Do you have access to a scanner/code reader and a hand vacuum pump?
Those are the tools I use to find out where the problem is. I guess you could use a volt meter and read the voltage at the dpfe sensor ( you will have 5v on one wire, ground on another and around 1v on the third). And the erg vacuum regulator works on a voltage duty cycle.
When the computer commands EGR flow, it sends a signal in the from of a duty cycle to the vacuum regulator. The regulator should have manifold vacuum at idle on the red hose. when the vac reg is being commanded on by the computer it will supply vacuum onto the green hose that goes to the EGR valve. This vacuum supply is what opens the valve. This lets exhaust flow into the manifold thru the egr port in the elbow behind the throttle body(the part that was full of carbon). The Dpfe sensor reads a difference in pressure across a restriction in the egr tube that is between the exhaust manifold and the egr vavle. The DPFE sensor sends a voltage signal to the computer in the form of a voltage reading. At idle/ no egr flow, the signal should be about 1 volt, some older type of sensors(metal ones) signals would read about .5-.6 v. This signal will increase to about 4.5 voltes with full erg flow.
If you have a way of reading the voltage at the dpfe sensor and a hand vacuum pump you should be able to trace down the problem with the info above.
Here is a list of some of the things that could cause a code p0401.
no vacuum to the solenoid.
no vacuum from the solenoid.
no signal to the solenoid from the pcm.
no power to the egr vauum regulator
stuck shut egr valve.
no vacuum to the egr vavle.
bad dpfe sensor
a bad or clogged dpfe sensor hoses.
a bad solenoid
clogged egr port in the manifold.
a bad pcm

also the vacuum solenoid has 12v to one of the wires and is grounded by the pcm(duty cycle).

Read thru all that and see if it helps. And also remember that just because a part is NEW, it does not mean that it is GOOD.
Hope this helps.
By the way,could you tell I am a FORD TECH?
GOOD LUCK!

 

[blu02expy]

Okay I had the codes pulled again...

p0401---EGR flow insufficient

p1401---DPFE sensor circuit high

p0302---Misfire Chamber 2 (this is now the one that worries me the most. I changed my plugs about 6 months...7k miles ago. Hopefully this is being caused by the EGR problem... Going to replace the sensor tomorrow.

 

[blu02expy]

Okay I had the codes pulled again...

p0401---EGR flow insufficient

p1401---DPFE sensor circuit high

p0302---Misfire Chamber 2 (this is now the one that worries me the most. I changed my plugs about 6 months...7k miles ago. Hopefully this is being caused by the EGR problem... Going to replace the sensor tomorrow.