I have a '86 sammi all stock w/ all emissions intact. I have noticed that I cannot get the egr valve to move when revving the engine like the manual says it should. I have checked all of the components and all seem to work (I couldn't check the egr modulator but switched it with another one and no change). Anyway - I took the egr valve off and found what I expected -carbon clogged - so I cleaned it out and the ports comming from the intake manifold. So for my questions - Is there history of the whole ports in the manifold to be blocked and need removel/cleaning? And two - I noticed that the vacuum comming from the carb - going to the timing advance/egr system "t" has very poor vacuum but does not appeared clogged - is this normal? No matter what I do it stills backfires with backpressure out the exhaust is this a egr problem? thanks for the ideas - sorry for the long post. Jason:smokin:

I don't think your back-firing problem is related the EGR. You very well could have a whole in your actuator diaphram in the EGR which would keep it from operating. Also, It doesn't take much buildup to keep the diaphram from moving. I recently removed mine because of very poor performance and surging under acceleration. I tried the celaning thing, with no luck, so I fabbed a small plate and stuck it between the EGR and the manifold. The performance improved, so I am guessing I need a new EGR. Unfortumately it is a dealer only item, of which they are very proud $$$$.

I cleaned it out and tested it. I holds vacuum just fine. Have you heard of the whole passage that it bolts to on the intake manifold being plugged with carbon? I'm thinking of pulling the manifold and checking. How much vacuum is developed from the nipple on the side of the card that hooks up to the egr system? It goes from the carb to a bimetalic switch to another electrical switch to the egr modulator then to the egr. Its t'ed before the bimetalic switch and also goes to the timing advance. You can tell I've been studying this thing, any ideas on the constent backfire?

thats what mine did when I burt a valve! Its common.