Well, my NOx is too high on my 91 Tracker, and I checked the EGR Valve. It opens up, but not until 3200 rpms, which is too high!

Is this the rpm it normally opens up at, or is something worng, like the EGR valve is shot?? Help!!!!! It won't pass E-check.

Buy yourself a $1 gasket and pull the EGR off. You'll find 2 "large" ports (a bit smaller than a dime) that will probably be 2/3 filled with carbon. It's a taper hole, but the holes in the manifold and valve can be scraped clean w/ a knife or screwdriver. Wash it out with carb cleaner & let dry before putting back on vehicle. (Any loose chunks would be bad.)

What *can* cause late opening is the inlet (vacuum line) tube in the EGR. It can also carbon up. A 1/8" drill bit will remove most of the carbon in both the EGR and the temp sensor. (I've seen them nearly blocked w/ carbon in all 4 places... meaning slow/late opening of EGR & less gas recycled.)

...just a thought.

The passages are most likely filled with carbon.  Pull the EGR valve off and scrape all the stuff out of it.  You may also need to pull the exhaust manifold and run something through the passage in the head/intake to clean it out.

As far as the late opening goes, there is a vacuum modulator that senses pressure in the EGR passage and opens the valve more as exhaust pressure increases.  If the passage in the head and intake are clogged, you will have less pressure, which will cause the valve to get less vaccum and open later.