I was told that on a good EGR vlave I should be able to puch the diaphragm inside it with my fingers. I tried this with mine and could not do it. Could this be the source of a backfire on acceleration and very bad 1/4 mile times? Oh yeah, I'm not getting an SES light.

Andy

 

There is little room to actually get your fingers in there, but it can be done. The diaphragm should be able to be moved with some effort. It should then return to where it was because of overriding spring pressure. You can also check to see if it is capable of operating by applying vacuum to it when the engine is idling (kinda the same as pushing on it with your fingers, but better). The engine should try to die when you do this.