Got a mates 9-3 Turbo on the drive B204E engine just failed its mot on emissions , not showing any fault codes. High 02 readings and from obd2 diagnostics last night we are showing a high long term fuel trim (15%) so short story is its overfueling.
Its had a new o2 sensor and cat, New thermostat and new fuel pump and fuel pressure sensor + all new silicon vacumn hoses recently.
It now passes emissions at idle but not at Fast idle - still a few % too high
It is popping on overrun , and hunting at idle. But other than that it pulls like a train and drives grand.
I am fair certain its going to be an air leak between the MAP and the turbo OR a faulty MAP leading(but i think this would throw a code) to overcompensation with fuel.
Im struggling to convince him though - anything i can do that will pin point it to that area. - all my petrol engine tinkering comes in the form of N/A Carb engines.
OR on the other hand any other ideas for where to look for a fault on this engine.
EDIT * ARRRRGG Wrong forum. Can you move it please mods ?