Ive seen these around everywhere, but i don't really know what they do. I know its kind of a goofy question but im curious. They say that they eliminate a check engine problem on FI cars....what sort of problems are they speaking of?

 

they are made to fool your map sensor into not reading as much boost (over 11.5 psi) and in my opinion are ******* stupid. It's like a band-aid fix as opposed to say a GM 3-bar map sensor. If you run a missing link, you may as well just rely on an FMU as well for fuel management.