Not a GS question...

[Larry D]

I know, I know. It's not a GS question, but you guys are really smart about alot of other things too !!

Had a coworkers MAP sensor go out in his truck. What the heck does a MAP sensor do ??

[doctorgonzo]

I get to return the favor!

It measures the density of the air coming into the manifold so the computer can adjust the mixture.

[Larry D]

I get to return the favor!

It measures the density of the air coming into the manifold so the computer can adjust the mixture.

Thanks. So, it's was very cold here last night (-1 to +1) I'm guessing he was having trouble with his 2006 Chevy 2500 Dura Max diesel, because the air was so cold and therefore much more dense ? And the 'puter was having trouble adjusting the fuel mixture properly ?

He is working on his end to get the problem solved. I was more curious than anything. And thought our GS family could help point him in the right direction.

[SqDancerLynn1]

Does he have K&N filter ? Sometime if they are over oiled it can screw up the MAP Has he tried to clean it ???

[asetech]

An over oiled filter will screw with the maf sensor not map. maf=mass air flow. map= manifold absolute pressure

[bwringer]

Correct -- sometimes you can clean a MAF sensor (they use changes in the resistance of a heated wire to measure airflow, and you can often improve things by cleaning the wire), but a MAP sensor pretty much either works or it doesn't. The only things that can go wrong with a MAP sensor are moisture or other mung in the tubing, fittings, or sensor, or a problem with the tubing leading to the sensor. (If it's an external sensor, that is.) Or, of course, an electrical problem like moisture in the connector or something like that.

The MAP sensor might give you some wacky readings if the intake was badly clogged or open -- maybe something cracked or left loose or came loose.

MAP sensors are very reliable -- usually it's a loose vacuum tube or the intake system is unsealed or broken somewhere.

[focus frenzy]

also, on the duramax (turbo diesel) the MAP sensor tells the ECM what kind of boost is in the manafold so it knows how much fuel it can inject.

now a days that is nearly a bullet proof sensor. rare to get one that has failed, especialy with those Isuzu engines they are putting in Chevy pick ups.

[Larry D]

To conclude this....he found out that there was some frozen moisture in the larger aftermarket cold air intake that he had installed over the summer. After he limped into work yesterday, he pulled his truck into our shop and let it sit inside a warm enviroment, the moisture evaporated and it hasn't had any problems since.

Thanks Everyone for your knowledge.

[focus frenzy]

those so called cold air intakes cause more trouble than they are worth.

good way to suck up water and ruin a good engine.