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Old 07-14-2017   #1
Join Date: Jul 2009
Location: Rocky River Ohio
Posts: 310

GTA Year: 1989
GTA Engine: 350 TPI Automatic
Opinions/Advice re: catalytic converters

My car is a 1989 5.7 with dual cats. Car has 71,000 miles. Original cats replaced about 2 years ago - had loud rattling sound and one had physical damage from a speed bump. Local muffler shop replaced them with no name economy cats. Now these things are rattling like marbles in a coffee can (the old metal kind). The shop replaced the one we thought was making the noise at no charge. Still rattling so the other one must be bad also. I've put on less than 1000 miles on the first replacement cats. The car runs very well with no issues and no SES light. I don't know what is causing the cats to fail so soon, other than their poor quality.

The car is over 25 years old and is exempt from emissions inspection. I am considering removing the cats and replacing with straight pipes. (For off-road use only!). I don't intend to sell the car, but if I did I would disclose the lack of cats to a buyer. Has anyone removed the cat(s) from these cars? Are there any engine/drivability issues that result from this? Will it set off an SES light? (No O2 sensor post cat, so I doubt it, but…).

If anyone has any experience with deleting the cat(s) on these cars I'd appreciate your input.

Last edited by 89-5.7GTA; 07-14-2017 at 12:11 PM.
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