IDM sensor thing question

[Red '97]

Alright so i was in town and saw my buddy, when i drove up to say hi he told me to pop my hood so he could show me something. before i know it he had unplugged a sensor with wires leading into it that was located up and to the left of the turbo at the back of the engine bay, against the firewall. he said it was the idm sensor and unplugging it added like 15 horse. now this dude aint that bright when it comes to 7.3s, but still drives one. anyways i go drive around for a bit with it unplugged (dont flame please, i know) and the truck seemed to have a little more power, and dumped WAY more smoke... it also threw a CEL. i shut it off, plugged the sensor back in, and turned the truck back on. cleared the CEL. truck drove4 fine with it plugged in and unpplugged. question is, what is it that the kid actually unplugged, why did the truck respond to it the way it did, and is it really harmful to the engine? thanks in advance!

[lwillson]

Sounds like your MAP sensor (Manifold Absolute Pressure). Was it right above the heater assembly, with a hose going to it?

Its used to measure the air pressure into the engine, essentially measuring boost and ambient air pressure for the computer.

[Red '97]

that sounds more accurate... the trucks air fuel ratio was definatly different

[Red '97]

more input?

[jesilvas]

That it? This is an upgraded one, but you get the idea.

[Red '97]

ummmmm i think so. its definatly what Iwillson described, the MAP sensor. ill post a pic when i get the chance

[jesilvas]

When unplugged, the PCM just sets a default value for the MAP. It must be fairly high, so it fuels more to match the MAP value which is more than what is actually there.

[baderic03]

Originally Posted by jesilvas

That it? This is an upgraded one, but you get the idea.

That's a boost fooler that is need on a sd with tunes and over 23psi not needed on a obs truck

[jesilvas]

Regardless, the location is for the MAP sensor and sensor is back behind there.

[Red '97]

okay so when i unplugged that, was the truck putting in less air or more fuel? because it smoked a lot more and it seemed to have a bit more power