Egr function is about volume of flow. A small reduction in cross sectional area creates a large reduction in the volume of egr gas flow. So I suspect these egr plates need to be kept clean for this super high performance Insight engine to do it’s job at 80-100mpg.

I ended up touching up the egr plate with q-tips and carb cleaner. The carbon is so dense and sticky that using the small screwdriver to get 99% of the carbon out was a mandatory first step! The egr jets (blocks) have tapered holes, so getting into each of them takes a little diligence.

Far better!