so, stock 87, NA,

is it possible for the EGR to become So clogged that it will effect the vacuum system, and the normal operation of the motor--- like stalling and flooding

 

I don't see the above happening with the EGR. It has been written that the EGR can cause idling problems. The way that happens, is if the diaphram inside the EGR is busted, which results in a vacuum leak.

All you have to do, is remove the line from the EGR solenoid that goes to the EGR. Attach a foot or so of spare vacuum line that you might have or buy a foot of it. Then suck on that piece of vacuum line going to the EGR. It should hold a vacuum. If not, the diaphram inside the EGR is kaput.

You could also idle the engine when fully hot, and suck on that vacuum hose at idle. The idle should change tone when doing that.

 

I've noticed on two seperate egrs (one off my car one off a parts car) that the opening around the bottom does get caked pretty bad with carbon build up. I also found it in the hole going to the egr diaphram itself. It didn't seem to affect the ability to hold a vacuume at all though. But it was really caked in there!

 

Forth worth, isn't that an army post, got to expect the army to know about sucking, hehehe, my bad bro its all good, thanks for the advice, it actually does make sense, if you were wondering im AF based out of balad iraq right now.

and dogie actually the reason i asked is because i noticed that to with the egrs getiing caked up really bad

 

It does not take that much effort to pull the dynamic chamber off and pull the EGR off. I agree, you'll see a lot of carbon cake there. But I'd still check the diaphram out in the EGR. Come to think of it just now.......the EGR only gets vacuum when the car is driving along and very rarely then (like in fifth gear conditions). It'd never have a vacuum while idling in the driveway.

And yes, I was in the Military (Army, US54357xxx), unlike you, who are in the AF. Your akin to someone who'd be in the Marine Corp. They created the Marine Corp and stationed them on ships so the Navy personel would have someone to dance with on the weekends. Touche!

Coast Guard to be slammed in a later post.

 

Aside from not passing the visual portion of the smog test (assuming the tech even checks it), does a busted EGR valve affect anything else? Like running rich/lean, etc?

 

Carbon buildup is common, especially on engines with high miles. Diaphragm problems are much less common. Both of these problems can result in higher than normal nox levels. Rotaries are not known for being high nox producers. Mazda deleted the egr system on the s5 models, as a result of changes in spark plug placement and slightly richer fuel maps.

One thing that has not been mentioned is that the egr valve is supposed to be completely closed at idle, meaning zero flow. I have seen a few egr valves that had a chunk of carbon lodged between the valve's pintle and seat, causing flow at idle, with reduced vacuum and rough idle. On piston engines, you can sometimes dislodge the carbon by applying higher than normal vacuum to the valve's vacuum port with a good quality vacuum pump, say around 20" vac. Then you tap around the base of the egr valve with a hammer and punch to help dislodge the carbon. This doesn't cause any harm on a piston engine, but on a rotary you could end up with a chunk of carbon being chewed up by an apex seal. If a customer brings a rotary car to my shop with a rough idle concern, I usually check for vacuum leaks first to eliminate that, as well as any other causes of rough idle. If I then suspect the egr valve, I remove it and use a piece of fuel hose held against one of the flow ports. If I can blow air through one port and it comes out the other, the valve is stuck open with carbon. It is best to replace it rather than to try to clean it.