Fuel Injector Leakage Inspection
Remove the spark plugs. Note the cylinder from which each spark plug was removed. Check that none of the spark plugs have a lighter or darker color than the others. If any of the spark plugs are lighter or darker, this may be an indication of a defective injector. Replace as necessary. See FUEL INJECTORS under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - S40 & V40 article.