mrspeedy69

I have a 97 civic hx that keeps throwing the code P0420, which I'm almost positive the cat is bad on the car. The car is also not getting the gas mileage I think it should. When I first got it, it was getting average about 36 or so. The other day I got 31 in the car, which makes me believe the cat maybe clogged.

But what I'm curious about is I know you should never gut your cat for emissions reasons. I plan on trying to buy a new cat and manifold but till I'm able to afford that would it hurt anything to gut the cat? Like I said I plan on buying a new cat, I'm just hoping this will solve some of the low MPG problems.

civic_driver

Yes, that will work.

It's also possible that the secondary O2 sensor is not reporting right and your cat is okay. If the cat was clogged, you'd be having bogging problems.

On a side note, I'm not sure if the cat can go bad and still not be clogged.

1slowgreeneg

i had a clogged cat on a kia (i no its not a honda its my dads) it bogged so bad and would sputter...the car sounded like it was reving realy high but would be at 3k..i let the car run for a little and tuched the cat and if its extreamly hot its clogged (i did get burned but i fixed it lol) the cat i had was under the car so it might be a lil diff but i thought i would try

Evans1109

Test at night, if the cat is bad you should see it get cherry red, mine did on my car.

Unseen Racer

no. nothing bad will happen if you gut your cat.
you will get SLIGHTLY more hp since there isnt anything restricting the air flow.
it will be pretty much like a str8 pipe.

but as mentioned above, replace your secondary o2 sensor. since it may be out.

vtechjunkie

iTrader: (2)

I have a test pipe I'll sell you for $20 + shipping. You can still switch it out for emissions.

waaBAAH

isnt the hx model the one with the cat on the exhaust manifold?

i also think if you have less then 150k miles then your cat converter will covered by the dealer...but im not 100 percent sure on this.

you could have a cracked manifold before the 1st o2 making the motor think it is running lean resulting in more fuel being dumped into your motor lowering your MPG.

mrspeedy69

So I took the heat shield off and immediately found the problem probably. The manifold is cracked so I'm probably going to have to buy a new one. Do you all think JB Weld might help it out a little bit?

tha_badguy

my manifold is cracked the same way but I have no CEL's & it runs fine.

a new oem one costs like $600

if you think ur cat is clogged have someone rev while ur next to the muffler

u should be able to tell.

supra-n-civic

ebay. get a nice tubular that will work fine for 6 bucsk mailed to your door everyone knocks ebay but if you need it and your on a budget you cant beat it

supra-n-civic

civic_driver

His manifold is probably cracked all the way through and air is getting in the exhaust so the O2 sensor reads high all the time and the ECU detected that that's wrong and raised a CEL. Yours might not be cracked all the way through and the O2 sensor is working fine so it's not throwing a code.

mrspeedy69

Can you show me one that you're talking about? All the ones I've found for the HX have the cat and manifold all in one piece and they aren't just 6 bucks.

ej1love

im puttin my headers on today; a 2 piece... how do u gut the cat, cause i have some bogging issues too?

sicones

Magnaflow now makes aftermarket replacements cats for the 96-00 civic non-vtec and HX. I'm not sure of the price but it must be much cheaper that an OEM manifold.

The best alternative is to get an EX header and pair that with an EX style cat, you can get an aftermarket EX header for $50 on ebay and a magnaflow EX bolt on cat for $70. No CEL and a better style exhaust setup.

p nut

Hey, if you haven't fixed this already, I just found out that 1997-1998 HX's have an extended Honda warranty. 14 year or 150,000 miles.

Unfortunately, mine's over 150k. Sucks. This is what I found in mine. Need to get it replaced.



Sicones - Thanks for the heads up on Magnaflow. I'll have to check it out. Autozone had one from Bosal which is ~$350. It does have a lifetime warranty, which is good. Not sure if anyone has had any experience with these?

EDIT: Here is a good link with some good info. LINK