Codes P0171/174. Engine runs flawless. Have smoke tested and confirmed there is no vacuum leaks. Checked over the brake booster line and supercharger fitting those are all fine.


Now my drivers side catalytic converter is rattling. 172k miles it’s expected they go bad. Unfortunately I live in California and need to get the car smogged. What are my options ? No code for the cat yet I wonder if I can just dig out what’s rattling and put them back on. Is it possible that the cats are causing the 171/174 code ? Would 90 degree defoulers fix this? Thanks for the help guys

 

Do the incredibly simple test for whether it's a leak: is any trim high at idle & drops when revved?

 

Maybe the ratting cat is just a heat shield?
Easy to rule out on a lift.
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