Pre-Cats

[mojo92]

Is it bad to cut off the pre-cats and still have the main cat still on and working ?

 

[ZumZum]

Short anwer: No. It won't hurt anything mechanically or electronically to get rid of the precats.


The precats are there because old technology cats didn't work very well till they got hot. The precats, being close to the manifolds heated very quickly and so would limit emissions until the main cat got hot. If you don't have any emissions testing you can eliminate the precats with no problems. If you have a visual inspection of the smog controls you may have some problems with that. If you have emissions testing at the tail pipe you can eliminate the precats, but it may be in your best interest to replace the main cat with a modern design cat or drive the car spiritedly to the inspection station to make sure the main cat is hot enough.

 

[mojo92]

Here some videos of how rich it is running....

 

[mojo92]

Let me tell my story... I got the car with 192,000 miles on it I drive it home from above Atl. ( thats about 3 hrs.) the car ran fine it was just loud. The guy had drilled holes in the pre-cats cause he said they were stopped up. That Monday I had the pre-cats cut off and a week after that I had SpinTech race mufflers put on. It ran fine for about 2 weeks then it started acting up really bad. White smoke and black smoke, and the car would have like a bad lope to it driving down the road ( like if you had a really big cam and was setting at a red light where the car would want to go but couldn't ). Now I have had the motor rebuilt and everything changed and now it is running like crap ! It still has that lope to it going down the road and it is dumping gas like crazy. The guy that redone the motor did not check the ohms on the injectors nor did he check the tps nor the map sensor. My dad tested it and it had a code of 460.We don't know what the fuel pressure is nor is the timing set right,I really need some help with this if anyone that know anything about vettes and that lives anywhere around Tifton Ga., Albany or Valdosta, Macon, Alt PLEASE SEND ME A PM.