vacuum to EGR

[SamNovice]

I have 1998 windstar 3.8L. It runs fine, but lately the idle has been rough. I pulled the vacuum line to EGR and that fixed the rough idle problem. I noticed that there is a slight vacuum in the line while idling. Is this normal??? How is the vacuum to EGR controlled? Shoud I replace EGR valve? Suggestions would be very appreciated.

[wiswind]

It is NORMAL for there to be a slight vaccum in the hose to the EGR valve at idle.
The EGR valve is not known for being a high failure item.

The 2 most likely causes of your problem are clogged EGR ports in the lower intake manifold and the EGR flow sensor, aka DPFE.

The EGR flow is through a pipe that goes from the front exhaust manifold to the IGR valve, which is mounted in the lower intake manifold.
The flow then goes to each cylinder's intake through the lower intake manifold and enters each intake flow through a small 1/4 inch hole.
The EGR ports clog right at the end.....right where they enter the main airflow.
What normally happens is that these ports clog more on the driver's side first.
This ends up with the 2 ports on the passenger side being the last ones open...and all the EGR flow is now going to 1 or 2 cylinders.....starving them of oxygen.....causing the misfire.

To clean the EGR ports in the lower intake manifold, you MUST remove the upper intake manifold.
Then, it is easy to clean each port.
Use care to avoid getting any fluid or dirt, etc down the intake ports that go to the cylinders.
A small screwdriver and shop vac are excellent tools for the cleaning.

This picture shows the lower intake manifold, with the upper intake manifold OFF.



A closer look at a couple of clogged ports



The gaskets on the bottom of the UPPER intake manifold are reusable.....they are shown in this view of the bottom of the upper intake manifold.


The DPFE (EGR flow sensor) is also a common failure item.
It is easy to change.
The 2 hoses going to it are slightly different sizes, so you will know if you try to switch them.
In the picture that I am posting, mine is the "old grey style" the newer style is black.
The DPFE sits right out in front, so you don't have to remove a bunch of stuff to change it.

[snshddog]

I have had that same problem, fixed it by spraying a bit of intake cleaner in the line with the engine running. afew short sprays and it fixed mine.

[SamNovice]

Thanks, Wiswind. Since my egr ports were cleaned not long ago, I'll try to see if my dpfe is any good.

[SamNovice]

snshddog, which line did you spray, the vacuum line to EGR???
Sam