I hope you guys can help me. I have an 04 MT RX-8. I love this car and it now has 56K miles (Still original engine). When I am idling at a light, there is a strange vibration I can feel in the seat of my car like sputtering noises (low bass feelings). The RPM's drop very slightly, almost where you dont notice it and does not stall or anything like that. No hard vibrations either. When I get out of the car, the engine sounds normal and the car feel and rides strong like it always had. It's just weird to feel like it is misfiring but I only feel the vibrations, not to strong but there. Do you guys know what it could be...? I brought the car used about 11K miles ago and I don't know if the plugs or coils have ever been changed but like I said, it rides strong and smooth.

Gary

 

could be engine mounts

 

How much are engine mounts-if a dealer is doing it?

 

Should be under warranty still for engine mounts. Mine does the same thing, I don't really notice very often though.

Change your coils, plugs, and wires too (every 30k at least). You are setting your self up for misfires and a what not.