I just had my 2004 GMC Safari tuned up with new plugs & wires and it is now knocking during highway driving acceleration as well as sometimes during acceleration from a stop. What would cause this? Something not done properly by the mechanic tuning it? It didn't knock before it was tuned.
engine knocking on 2004 GMC Safari
Its hard to guess without actually being able to drive the vehicle and experience the problem first hand. If this noise wasn't there prior to the work being done I would go back to them and ask them to drive the vehicle with one of there mechanics in the vehicle with you, let him experience the problem with you. It could be something simple or something that could result in more serious engine damage like detonation. It may have nothing at all to to do with the repairs just done but any repair shop that has previously just done work on a car should be obliging enough to at least go for a drive with you and give you and opinion,