EGR on 09 chassis cab
 

I have a bone stock 09 cab and chassis 3500 with manual trans and about 2000 miles on it. Overhead mpg is usually around 18 and I rarely go over 65 since it's a 4.10 ratio. I tried unplugging the egr and crossover connections and lost some power, the truck didn't seem to be running right and the overhead said 5-8 mpg. CEL came on as expected. I was worried something might be different with the 09's so I plugged the stuff back in. My mileage was around 8mpg for a while and slowly came back to normal. Is this what normally happens, and should I give it enough time for the ecm to adjust? Does anybody else have experience with 09 or late 08 trucks?

What crossover connections? You should of just unplugged the egr.

There is a sensor in the crossover tube and it is my understanding that it needs to be unplugged along with the egr plug.

the sensor in the crossover tube on the cab an chassis is a egr temp sensor.

[QUOTE=shooter71;2329555]I have a bone stock 09 cab and chassis 3500 with manual trans and about 2000 miles on it. Overhead mpg is usually around 18 and I rarely go over 65 since it's a 4.10 ratio.

First off, if your overhead is showing 18 with 4.10 gears, IT IS WRONG!
My 2007 has 4.10 gears and I run with the cruise set a 65mph and the best I have seen at 25-k miles is 14.7 on the overhead and right at 14 by hand. The first 20-k the best I seen was just over 13!

I would check it by hand then go from there.

I'd wondered about that sensor also. I haven't tried unpluging it. I did unpluge my EGR but didn't gain any MPG. From what I'm finding get rid of the DPF. You might look into a code reader/clearing device. www.scangauge.com is one I've used for years. Lots of others out there.
Could you fill out your signature so we know what you have.