What exactly is a MAP sensor?

What exactly is a MAP sensor?

It is MAF sensor = Mass Air Flow... or MAP sensor...unless your lookin at a GPS?

Map stands for Manifold Absolute Pressure.

What exactly is a MAP sensor?

It's a sensor that measures pressure in the intake manifold.

How is that related to Limp Mode?

MAP sensor = Manifold Absolute Pressure. Remember, this has nothing to do with fuel gelling. Gelling happens when it gets cold outside and the fuel turns into a waxy, jello like substance that is worthless to any internal combustion engine. :)

Some of us have an 07.5 that has a TSB out for it. When it snows outside, the snow and ice make their way down the intake and freeze up sensors. When a sensor is all froze up, it cannot read correctly - hence setting a check engine light and LIMP mode. :)

How is that related to Limp Mode?

The MAP sensor measures the MANIFOLD Absolute PRESSURE and if the turbo exceeds pressure as determined by the MAP sensor. The sensor tells the ECM to go into limp mode. It is not likely that your turbo did this so it indicates a faulty MAP sensor.

I'm new to "cold weather diesel operation" so forgive my questions. In cold weather other than gelling what would cause my LMM togo into Limp Mode?

Some of us have an 07.5 that has a TSB out for it. When it snows outside, the snow and ice make their way down the intake and freeze up sensors. When a sensor is all froze up, it cannot read correctly - hence setting a check engine light and LIMP mode. :)

If your getting snow and ice past your filter...you've got a problem. But, if your filter is plugged, the MAF sensor (mass air flow) will tell the ECM to go into limp mode because of a lack of air flow.

I'm new to "cold weather diesel operation" so forgive my questions. In cold weather other than gelling what would cause my LMM togo into Limp Mode?

It gets cold in North Carolina?

It doesn't get cold here in NC, relatively speaking, But I am planning a trip to N.Illinois in a few days.

If your getting snow and ice past your filter...you've got a problem. But, if your filter is plugged, the MAF sensor (mass air flow) will tell the ECM to go into limp mode because of a lack of air flow.

What happens, here, is the filter packs up with snow and ice and then it gets warm enough in there to melt some of it. The water gets pulled through the filter, hitting the MAF and MAP sensors. When the water is hitting the sensors, the cold air rushing by them freezes it. Check out the TSB - search "new fix LMM" or something like that. It's not a good problem to have at all. With the TSB fixed, they give you a new air filter, and a new intake tube. Apparently it works.

It doesn't get cold here in NC, relatively speaking, But I am planning a trip to N.Illinois in a few days.

You should be fine. This service bulletin only applies to 07.5's. The 08's had the fix already done to them. :) Enjoy Illinois!

What is the TSB?

Here ya go. http://dieselplace.com/forum/showthread.php?t=203657&highlight=new+fix+LMM

And I lied, it's for 06-08's...sorry, my memory served me wrong. It happens sometimes. :(

Some of us have an 07.5 that has a TSB out for it. When it snows outside, the snow and ice make their way down the intake and freeze up sensors. When a sensor is all froze up, it cannot read correctly - hence setting a check engine light and LIMP mode. :)
Does this problem extend into the 2008's as well? I have done some serious plowing this winter & had my grill accumulate some serious ice and snow build up, so much i had to clear it on several occasions. No limp mode problems thus far!

Sure does...click the link above and read, pretty good info. I think you have to have an air filter packed with snow or a P0101 or P0106 showing for them to fix it though!