Honda Repair Questions? Ask a Mechanic for Answers ASAP
If the Turbo is overboosting.then it means the turbo is spinning faster then it should be and this will cause it drop into limp mode..I think the obvious step here is to see the VNT actuator arent sticking.the turbo is vnt so maybe the vanes inside the turbine housing is sticking. its quite common on alot of these vnt turbos..only way to know that is to disconnect the actuator rod and manually move the vnt lever on the turbo to feel is its sticking or siezed inside with carbon soot build up,you'll know if it feels hard to move back and forth or crunches..the turbo on these 2.2crdi's sits right at the front behind the heat sheild..so its not difficult task to reach the turbo itself...you see that the Rod actuator is operated by vacuum.they'll need to check that holds vaccum so directly fitting mityvac to it will confirm that although - the vacuum operated solenoid that controls the actuator rod should pull the wastegate/vane lever shut as soon as the engine has started and it should slowly release the wastegate/vane lever when the engine is turned off.so observe that. ..plus you also see a small vaccum hose leading away from the turbo upto a control solnoid check the line is damaged or leaking.....
But if your hear a whooshing noise under throttle..then that could well be boost leak somewhere.so of course an inspection of the intercooler system and pipes will need to be checked before going any further as to above..