85 automatic bad cat?
Thread Starter
Racer
Joined: Oct 2013
Posts: 483
Likes: 19
From: las vegas nv
85 automatic bad cat?
had this chugging sound figure it might be the O2 sensor since it's old replaced it still makes it engine sound smooth however if I listen down exhaust right where the cat is it makes a hard chug which leads out to the back pipe but from the engine to the cat sounds smooth any ideas
Burning Brakes
Joined: Nov 2000
Posts: 986
Likes: 487
had this chugging sound figure it might be the O2 sensor since it's old replaced it still makes it engine sound smooth however if I listen down exhaust right where the cat is it makes a hard chug which leads out to the back pipe but from the engine to the cat sounds smooth any ideas
Get rid of the cats. Wasted weight, wasted power, zero downside.
May or may not be your issue, but doesn't matter. The cats provide nothing of value on a 35 year old car.
Last edited by PacerX; Dec 14, 2019 at 05:34 PM.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
If you have the OEM cat, it may be starting to break down. The exhaust gasses are under some pressure and pieces of the cat may be clogging the pipe then releasing.
Do you have to take the car thru emissions testing? If you do, then you may have to order a replacement cat. If not, you can cut the cat off and install a straight piece of pipe. Most muffler shops won't remove a cat as that's a violation of federal emissions laws. They could get hit with a 5-figure fine if caught. But you can cut the cat off by yourself an then take the car to a muffler shop and have them weld in a piece of pipe. Just tell them the car is "for off-road use only"!
Do you have to take the car thru emissions testing? If you do, then you may have to order a replacement cat. If not, you can cut the cat off and install a straight piece of pipe. Most muffler shops won't remove a cat as that's a violation of federal emissions laws. They could get hit with a 5-figure fine if caught. But you can cut the cat off by yourself an then take the car to a muffler shop and have them weld in a piece of pipe. Just tell them the car is "for off-road use only"!
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
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From: Southlake, TX
Other than the out lay of cash, there is no downside of removing the cats. After 35 years of driving, different grades of fuel, gasoline additive, carbon/soot.....etc. It is very conceivable that your cat has some clogging.
Burning Brakes
Joined: Nov 2000
Posts: 986
Likes: 487
Yep.
The 1985 computer couldn't care less about the cats being there. I've data logged mine (as well as you can with the slow baud rate) and it's happy as a clam without them.
Team Owner
Joined: Jul 2004
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From: Hartford WI
Downside is it becomes noisy. IDK about your car but on my setup, it was tolerable with the cat on. When I ran without, it was a headache maker. Wife rides with me only for short distances as it is with the cat. Without, she doesn't want to step in it even for short distances. I am running LT headers with 1 cat and a Borla Stinger cat back.
Team Owner
Joined: Jul 2004
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From: Hartford WI
If you wanted the front ones: https://www.autozone.com/emission-co...64807_0_234588
Last edited by aklim; Dec 15, 2019 at 10:56 AM.
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Team Owner
Joined: Jul 2004
Posts: 28,430
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From: Hartford WI
Thread Starter
Racer
Joined: Oct 2013
Posts: 483
Likes: 19
From: las vegas nv
