What would cause both Cat converters to fail at 20,000 mi.? Mine went out and the back pressure caused the engine to knock under acceleration. Also blew out an injector and plug. Luckily it was under warranty but wonder what could caused it. Thanks.

 

rich running condition?

 

Stuck injector. Watch for the signs of the others sticking if they didn't change them all out.

 

What signs should I look for to signal a struck injector.