It could be due to leaking valves. Do a wet test and if pressure does not increase, it could be due to leaking valves.
If you engine is VQ30DE, then you can check the valve clearance and adjust if necessary.
If any cylinder is faulty, you would have to remove the head or if piston ring faults, rebuilding is required.
Monday, July 6th, 2009 AT 12:34 PM