Possible IC Pump failure, question?
As a safety measure the supercharger will not engage if the temperature reaching the engine is too hot. So if the engine is cold then supercharger will work as normal but because the pump is not working the intercooler doesn't do its job, the temperature increases and eventually exceeds the limit and the engine management system cuts off the supercharger and also limits the revs to 4000.
I'm afraid you need a new intercooler pump. 71k miles isn't too bad, mine gave up at 65k!


