Adding a catalyitic converter

[Harry Mash]

Would it be "legal" in California and useful to run two cats in tandem to aid in reducing emmissions and passing the ever more stringent smog test?

 

[gofstbuick]

Legal, yes, but only on obd1 vehicles. Useful, no and even dangerous. That additional cat is no longer protected by a heat shield and an overly rich or misfire condition may (in an extreme case) cause your carpet to smoke. Therefore visualizing a GN car-b-que is not only scary, but sad.

 

[Harry Mash]

Gofstbuick, thanks for the response---let's say we meet the requirements for safety --- heat shield etc. are you saying that an additional cat would be no use in reducing emissions? From a novice point of view it would seem that more catalyst in tandem or maybe a larger single converter might help. Please explain your reasoning on this. Also please offer your thoughts on how we may reduce emissions on these cars. With the ever lowering #s on the smog test it seem that one day none of us will pass. Is this "planned obsolescence"?

 

[gofstbuick]

If the final O2 content reading is less than 0.3% during the test, then an additional cat will make no difference at all. That would indicate that the cat is working at peak efficiency and can do no more for you.