Adjustable Fuel Pressure Regulator
On many boosted cars fuel pressure needs to be raised as boost is added to compensate for extra air. The Grand Prix uses 2 methods to control fueling which render an AFPR worthless. The MAF sensor on the car reads the airflow and tells the PCM how much air is coming in and therefore how much fuel to deliver. As you mod and increase flow the MAF reads more and increases fuel. The stock FPR changes fuel pressure with boost. As your boost increases so does your fuel pressure. By changing this function by replacing the factory regulator you make your car impossible to tune. Adding fuel pressure doesn’t change the maximum pressure because your stock pump is limited to low 60′s in psi. So even though you might add 5 pounds at idle and cruising you’re not adding that much at WOT. This makes tuning the car a nightmare. All the ZZP cars run stock regulators. If you have an aftermarket unit on your car, sell it and go back to stock. Thank us later…
matt5112 
