hey everyone well i bout a high-flow vibrant Cat. for my 97 manual civic HX (D16Y5).

so when i installed my header and Cat. and when i went to take it for a test drive my car started to act weird. when im cruising my car it starts to slow down like if i'm stepping on the brakes and letting it go and then stepping on the brakes again. so I decided to remove the Cat. and test drive the car with open headers to see if it will still do it and it didn't it was driving fine, i was able to cruise the car with no problems.

Now when i call the guys that sold me the cat. they said that my car needs to relearn it's self because it has a high flow Cat. or i can get it tune. I never anything like that

Anyone know what could be wrong???

 

I think the guys you called are full of it. Cars don't have human characteristics even though many people talk as though they do. It is not trying to think out some changes and all of a sudden it will have some revelation and sort out everything.

I haven't worked on a 6th gen yet. Does it have a post cat O2 sensor? Can I assume it's not throwing any codes?

 

my car has two O2's i welded a bung after the cat. for the second O2. its throwing a cel for the primary O2 and i think because there's a wire thats expose and i think it causing a short

 

Well, I'm not the sharpest tool in the shed but I would probably fix that since it relates to your cat problem

 

anyone else

 

you wrote with a cat problem, you have two sensors surrounding your cat and one of them has messed up wiring. what else do you want?

 

it could also be your high flow cat might be a little too high flow which is messing with the o2's readings. inorder to fix that you need a mil simulator to lower the voltage being sent out by the o2 back to the ecu. this wires inline with your o2 wiring.

but if the wires exposed thats the problem cuz those wires are just a low voltage signal its not like massive power runs through them so rfi noise will disrupt the signal.

 

so why does it only do it when the high flow cat is installed and when theres no Cat. it runs fine

 

well as explained above do you have a check engine light? if so you need to make sure what is throwing the code before you go chasing something thats not there.

if you have no light on then run without the cat since these small honda motors dont even make enough pollution to hurt a fly i passed smog with no cat in vegas barely but i passed.

high flow cats can get mixed readings since its a form of both straight through and cat so one second its causing backpressure/heat next second its free flow and cooler since it lets more spent exuast out. too hard to explain if you wanna run without a cat i suggest a mil simulator/eliminator whatever you wanna call it they're cheap and basicaly keep your o2 from going haywire.