i am in the middle of building a different tpi engine for my truck. the current engine has the egr system on- and apparently it works. i took the truck to have the emissions tested the other day with the current 406ci engine in it. it passed with ease- actually it "fast passed" which in illinois, is extremely clean. it is titled as a 4cyl- but even with the 406 it ran clean enough to still pass with ease. my qyestion is- if i take the egr off the new engine will it make that much of a difference in the emissions? i dont wanna have to do what some people do with engine swap cars- register them to a p/o box that is someplace where emisions arent tested- i like the idea of having something that will pass.

 

I don't think it affects the sniffer test but it will fail a visual. Do they do a visual inspection in your state?

 

no visual inspections- but i am pretty sure that it effects the sniffer- just dont know how much

 

It effects things dramatically. You could definatly pass without it but EGR working lets in hot no oxygen = cooler burn. The cooler burn means you won't get a lot of Nox fumes and less HC because there is less usable oxygen to combust. The trick to passing the sniffer without EGR is to run slightly lean and the motor at 180 degrees. Then adjust your base timing if it fails for HC, if it fails anything else, do a search.