The convertor cleaner is most likely the cause of noise.
Most Toyota convertors are bolted on, if so, then remove convertor and look inside, if you see melted material or cracks/chunks of material then covertor will have to be changed and cause of problem fixed (rich/lean fuel ratio). Normal convertor looks like a honeycomb, some black soot is normal.
If convertor looks OK, then it may be a downstream O2 sensor that is bad.
If you cannot remove convertor, then have a backpressure test performed on convertor, it will tell you if convertor is clogged.
Convertors fail because of an incorrect air/fuel ratio or an impact event, such as running over road debris, convertor hitting a curb, rock etc.
Friday, January 15th, 2010 AT 10:42 AM