Do you really think it could make a 5mpg differance.

Where is the map sensor located. Is it the one in the air filter. If so, that maybe the problem. I recently cleaned my afe filter. Would it mess the sensor up if I used too much oil.

If it's the one in the air filter, and I used too much oil, could it make the engine run lean, making the soot go away like I said earlier. BTW,,,the soot is back now along with the better milage. Is it just a coincedence.

 

No such a thing in a diesel.

I see two responses blaming winter fuel. One from Indiana and the other from Utah. What would winter fuel have to do with it? why don't we see a change in AZ?

 

Mess it up, youp! Kill it, noop, it just interfers with its reading. It is a combo IAT/MAP Sensor and is located on top of your intake manifold held in with 2 T-15 Torx head screws. Clean off the top of your manifold so you don't knock dirt in the hole, disconnect the harness, take the screws out, remove it, clean it with a cloth, check the condition of the o-ring, wet the o-ring with engine oil, put it all back together.
Keep oil off the sensor.
Back to my morning beverage.

 

Winter fuel is blended for the region. #1 diesel is blended with #2, the colder it gets, the more #1 which has fewer BTUs per gallon. Unless you live up by Flagstaff you won't see that much difference in AZ.

 

I hate sounding dumb,,,but.

I have the afe stage 2 with the plastic tube. The map sensor is the one that I relocated to that tube,,,right. Moved from the stock air box.

 

Not dumb at all. I would have asked too. I should have been more specific.

This is the "Inlet Air Temperature Sensor/Pressure Sensor". It needs to be clean also. The one on your intake manifold is your "Intake Air Temperature Sensor/MAP Sensor". Make sure both are clean.

BTW, they normally don't need cleaning cause by the time the air gets to them (both are past the filter), it is supposed to be clean. But if you add oil to the airstream at the filter (over-oil your filter), then all bets are off.
Back to morning refreshments.

 

I tend to go with the change in fuel quality. Noticed my milage down for last couple months. Not as dramatic as yours, but definitelly down. Also you were pulling a three car trailer. One car sticking up high can really kill milage. Worst milage I get is with a tall load. Weight is easier than height.