Hope you guys can help me here. When under acceleration going past 2.5k revs and coming back down through the rev range, again at 2.5k, I am getting a rather nasty metallic sounding rattle coming from what seems to be coming from somewhere near the front nearside wing. I spent the best part of 4 hours on Sunday investigating it, wondering if it was something like a loose CAI pipe or something but I can't find anything at all. The only thing I can think of is that one of my cats has broken down internally.
The fact that is only happens at a certain rev range, to me, says it is either something loose and hence the resonance created at 2.5k is making it rattle or it is something to do with the exhaust gasses at that rev range, hence me thinking it is a cat but the noise seems too far forward in the engine for that!!
I know it is a huge long shot with me saying "I have a rattle, what is it?" but I am hoping someone may have had something similar.
The car is off the road at the moment until I have time to take the cats off an have a look at them but it's quite a long job!!
Any help would be greatly appreciated!
Cheers,
Andy