I had the same code.

The funny thing is that it probably doesn't have anything to do w/ fuel. ha.

My understanding of this code is this:
basically, your computer trims the amount of fuel being sent to the engine based on the amount of air coming into the engine. Your MAS plays into the reading on how much air is getting into the engine. The 170 is basically saying that you are not getting enough air into the engine and your computer can't trim the fuel enough.

For me, it was as simple as replacing the 02 sensor, and replacing my stock intake w/ an Injen intake. The reason why I replaced the intake was b/c my stock air box and filter was absolutely full of crap. It was blocking the flow of air, so I replaced it w/ an upgraded high-flow intake & k&n cone filter.

hope that helps.