EGR wisdom please anybody?

[citoboy_7]

2002 Ford Windstar

Few days ago i got codes 172 and 175. After some help, and some research i found the MAF sensor to be at fault. After i replaced the MAF sensor, the codes were cleared and did not come back (i also got 1406, which i'm assuming was remedied by replacing the MAFF sensor, as it has yet to return)

However, i now get code 402, which indicates "insufficient EGR flow" I checked the EGR, no leaks and opens with vacuum. I also opened, and cleaned the EGR vacuum solenoid (bolted onto the upper intake manifold, on the side closest to the firewall), and what appears to be the same part, with a diaphragm attached to the back, and bolted to the firewall. Both were dusty. I suspected they may be causing trouble, as vacuum to the EGR is VERY low, even after reaching operating temperature. I let my 96 Mustang gt which appearst to utilize the same system, run until reaching operating temp, and vacuum also seems to be VERY low to the EGR. But IT'S running fine.
(I forgot to mention, the van sometimes stumbles and even stalls (rarely) at low rpm)

I'm not too familiar with Fords EGR system, if anybody could pass some wisdom or advice along i'd really appreciate it!

Thanx!

-Aaron-

[12Ounce]

You will not improve engine performance by increasing EGR feedback ... just the opposite, too much EGR will nearly snuff out combustion. There is never any INTENDED EGR feedback at idle conditions ... only on a warm engine under load. So don't expect much of a vacuum signal at idle. If you were to put a guage on the line, you would read "zero" ... unless something is wrong.

"Insufficient EGR flow detected" is usually a problem with the detector (sensor) not the "flow". Look for the DPFE sensor that is hooked up to the EGR flow tube by two hoses. These sensors fail often and have to be replaced ... but first check the hoses to make sure they are in good shape and not stopped up.

[rodeo02]

The EGR jets in the lower intake could be plugged. There is one flow metered EGR orifice per intake runner. Often if several are plugged, so much EGR is forced to the clean jets it causes misfires on those cylinders.

Joel