One problem related to loud engine noise has been reported for the 2007 Lexus IS250. The most recently reported issues are listed below.
Lexus Is250 crank loud noise sounds like the car is going to explode. Lexus is aware of a camshaft gear problem and has recalled same or similar parts in other Lexus model vehicles due to safety issues. They also have an updated part available to remedy this problem but refuse a recall in this model.