How hot are they getting? Some of the causes of a hot cat are improper ignition timing, fouled spark plugs, air pump failure or a compression leak (burned exhaust valve). It could also be clogged. But other causes may include lean misfire (check for vacuum leaks, leaky EGR valve, low fuel pressure or dirty injectors). If the outlet temperature on the catalytic converter is more than 500 degrees hotter than the inlet that indicates unburnt fuel in the exhaust.
|