One of the dumbest things the engineering departments have ever done.
Spent gases run back into the engine is problematic at best.
Suet clogs the passeges
As well as hmm spent gases DON'T burn.
I get it the manufactur is trying to bring the cylinder temps down.
This can be achieved with valve over lap, thus allowing fresh clean air to pass over the pistion, and on into the exhoust side. Thus dropping NOx and carbon monoxide.
Seems that the big oil companies are doing great as we are still getting the same, or worse fuel economy.
Diesel is a prime example of this.
My 1st gen Cummins truck got 28mpg before the low sulfer junk, 23 after.
Same engine in a 2006 would be well under the 20mpg mark, move on to the 2010 and newer
These trucks are getting 9-14mpg. All this in the name of emissions standards.
Hmm twice the fuel use bring the total out put right back to where it was before all this fancy shamcy emission crap.
Fred-hope you can figure this issue out. Myron at ZOR (zuks offroad) may have some good info for you on this issue.