Toyota Repair: Supra Emissions (EGR), vacuum modulator, plenum chamber

Question
Hello
This is in response to some advice that you gave last week regarding my Supra and it failing emissions (NOx).

Over the weekend, I ran the EGR tests that the Toyo manual calls for and determined the following:

- The Vacuum Modulator is OK
- The EGR valve test: I applied vacuum directly to the EGR valve while idling and the engine did not stumble or die.

I then did the following:

- I verified, with EGR valve off, that there is emission flow out of the engine where the valve connects.
- I replaced the EGR valve (which I might not have needed to do)

I reran the vacuum test and the engine STILL did not stumble or die.

Does that mean there is blockage in the intake manifold? If so, how do you suggest I clean it?

Your thoughts?  

Answer
The most common place that clogs up is in the plenum chamber just behind the throttle body, this is where the opening is that puts exhaust gas into the intake system, most of the time this opening gets plugged up with carbon, if there is a small metal cover on the plenum chamber on top, remove it, you may be able to clean out the port through there, if not remove the throttle body and try to find the port on the bottom of the plenum chamber opening, use a stiff hook to probe around in there until you locate the port and clean it out, remove the egr valve again and when you can blow air through from the egr port to the intake port you will have fixed the problem.