Just a thought.

Would it work to force Highway Mode during the treadmill test and use Highway Mode to lean the mixture?

I recorded the last test and know the MAP runs between 30-40 at 25 MPH and 1850 RPM.

The HC and CO is high. It seems to me that by first forcing HM you could alter the AFR in HM at 30-40 MAP and thus lean the mixture.

Anyone see a problem with this?

 

Lean mixtures tend to increase NOx. Based on your other post, you don't have much leaway in that area either. When was the last time your cats were changed?

 

The cat has about 115K miles on it.

I Figured the Lean Mixture would fix the HC and CO, and if I can get the EGR DC from 65 up to 100 hopefully that will be enough to fix the NO.

Does this sound plausible?

One other thing I noticed that might help the 350 guys, they tested me as a 305 instead of a 350 which was good. A 305 is allowed more pollutants. This is in Atlanta Georgia.

305 limits 350 limits
HC=123 HC=108
CO=.69 CO=.60
NO=878 NO=751

My readings
HC=159
CO=.95
NO=1139

 

It might be time for a new cat...115,000 miles is a whole lot. I doubt that it's doing much good anymore.