low to no boost?

My friend has an 88' Conquest TSI with exhuast and air box mod, the car should boost 10lbs ,but at full throttle will only boost around 2-4lbs, does anyone know what could cuase this? (has a small stutter around 5 grand also)

My friend has an 88' Conquest TSI with exhuast and air box mod, the car should boost 10lbs ,but at full throttle will only boost around 2-4lbs, does anyone know what could cuase this? (has a small stutter around 5 grand also)
Check these out for being faulty, WasteGate, AirFlowSensor,FuelPump, Injector plugs for corrosion. If the car has the original type external fuel pump, You can almost bet thats the problem. Ironic as it sounds, this could have failed during the process of modifications. You also might want to check the o2 sensor for being clogged up with carbon. When you modified the airbox, you also modified the fuel consumption.

Go to www.kdmperformance.com and go to Ask Proffessor Quest forum and tell him your problem. He should be able to diagnose the problem for you. Also go to www.starquestclub.com as well as www.tristarion.com. I have a 88 Quest and a 89 Starion as wellas I just got a 98 3000GT SL on Monday. Goodluck and any questions email me anytime at [email protected]. I am a 41yo retired disabled Army vet with 23yrs in before being injured in Afghan in 20002. All I do now is stay home and play with my cars or online. Later,GAry