I'm experiencing bad fuel mileage in my 2006 cummins have had injectors tested and all is good, transition isn't slipping at all, I've read threads that if the iaf and maf sensors become dirty they can cause bad gas mileage, where are they located on a 2006 cummins?

 

FIRST CHECK FOR BLOW BY! It's on the intake pipe by the air filter.

 

No blow by at all , the sensor is clean but the wires leading to it look like they might be shorting or something they are bare and don't look like they have a good connection, would it throw a cel if this was the case? My heater grid still cycles for the first 5 min of idle when when it's 70 degrees outside could this be related to a bad sensor? Or is it normal. Any input would help Im stumped on what it could be cause my mileage to be this bad, hand calculated 8-10 on every tank

 

Yes it would throw a CEL if disconnected not sure what it would do if wires were bare and touching. Find someone to do a cylinder contribution test dealer most likely. Do you have a lot of black smoke? Boost leak? Clogged fuel filter, bad injector could be a lot of things. heater cycle at 70 is not good and means a false temp reading for the ECM which controls the grid! Check all your grounds for bad contacts