One problem related to engine knocking noise has been reported for the 1999 Honda Passport. The most recently reported issues are listed below.
After just pulling onto the highway from my parents driveway, I heard a "knocking" sound coming from the engine compartment of my vehicle. At regular idle speeds this sound could not be heard. After checking the oil it was found to be 4. 25 quarts low. The oil pressure warning light never came on and after adding oil back to the engine, the knocking sound still continues. The vehicle has been regularly maintained at service intervals well within the documented reccomendations of the manufacturer. The service has been completed at the dealership.