Catalytic converter install issue

[Erik]

So inspection is coming up for my mazda and the check engine light has been on for a a bad rear catalytic converter. I replaced the cat but now im getting a small exhaust leak at my flange after my cat, going toward my muffler. Its only leaking a slight bit but will clearly fail inspection. Anyone know what i can do for a temp fix until i get some money, or how much it would cost to get someone like midas to take care of it? Im hoping i just suck at bolting 2 pipes together and its not a ****ed up flange. Thanks guys.

[240sxDann]

unbolt it, high temp RTV on both sides of the gasket, smoosh it all back together. I did that on one car and it never leaked again for like over a year before I sold it.

[Erik]

ok, im guessing that can be bought at like a pepboys right? Ill give that a go. I think i used something similar to patch up a few pinholes on a muffler on my pontiac about a year ago. thanks.

[frosti108]

hell yea dan.

just get the high temp copper RTV ****. pep boys SHOULD have it, but might not. then try the hardware store.

works like a charm. my buddy even used it on his DSMs turbo manifold and it worked :lol:

[Erik]

awesome, so pressure shouldnt be too big of an issue. I cannot stand the sound of this leak. Ive drivin it for all of 20 minutes and i wanna scream.

[frosti108]

haha i remember u didnt like the exhaust leak in my s12

[Erik]

haha i despise that sound. Im actually pissed right now thinking about a leaking s12 and my protege. THANKS!

oh yea, side note, did casi ever get her title?

[Vr-4-Life]

awesome, so pressure shouldnt be too big of an issue. I cannot stand the sound of this leak. Ive drivin it for all of 20 minutes and i wanna scream.

you shouldnt have much pressure back there at all. any kind of DIY GOO gasket will be fine to patch it up.

[SovXietday]

Yeah, that copper stuff is a messy form of God.

[Erik]

awesome. ill pick some up tomorrow morning and see how it works through out the day.

[frosti108]

haha i despise that sound. Im actually pissed right now thinking about a leaking s12 and my protege. THANKS!

oh yea, side note, did casi ever get her title?


nope. havent seen it yet :bigeek:


and besides that, the ****ing car is a mess. did the timing and balancer shaft belts, headgasket, waterpump... now it seems not only the new transmission is slipping, :bigeek: but there might be a crack somewhere in the block thats letting oil into the coolant :bigeek:

its quickly turning into a nightmare. bout to just sell it and get something else :(

[Erik]

aw man thats awful. gotta hate cars that nickel and dime you huh. good luck with it.

[Erik]

So i threw on some high temp RTV red gasket stuff and i no longer can see the leak. I dont smell it but i hear something that sounds like a very raspy vibration. I had my typical heavy duty light lighting up the under carriage and the exhaust was pretty noticeable out the muffler since its cold so i couldnt miss a leak. Any idea what that raspy vibration could be? I only really hear it once i hit 3500rpm...

[93EGY8]

could just be the way your stock exhaust sounds once you hit a certain power curve in the motor, my civic gets raspy at 4k and it even did that when i had the stock exhaust.

[pinacup7]

So i threw on some high temp RTV red gasket stuff and i no longer can see the leak. I dont smell it but i hear something that sounds like a very raspy vibration. I had my typical heavy duty light lighting up the under carriage and the exhaust was pretty noticeable out the muffler since its cold so i couldnt miss a leak. Any idea what that raspy vibration could be? I only really hear it once i hit 3500rpm...

Did you buy a new cat? If not, the converter's inside's could be coming apart. You should of just made a resistor and tricked your ecu

[Erik]

could just be the way your stock exhaust sounds once you hit a certain power curve in the motor, my civic gets raspy at 4k and it even did that when i had the stock exhaust.
Thats a possibility. At idle, the engine sounds a little ****ty, its due for an oil change in 1k miles, but maybe ill put some real nice synthetic in it to see if it will even out.

Did you buy a new cat? If not, the converter's inside's could be coming apart. You should of just made a resistor and tricked your ecu
Could you explain? and yea, my old cat was bad. I took it out and i could feel it slushing around in there lol. New cat, new gaskets. How can a resistor trick the ecu?

[240sxDann]

O2 sensors read in voltage up to .05 I believe. The voltage is determined by how much of certain exhaust properties that their are (i.e. carbon monoxide etc). If there is too much of said exhaust properties, the voltage goes higher, which then tells the ecu "ok theres something wrong here, I shouldn't be seeing this much voltage, the cat is bad" and it throws a light. If you put a resistor in line with the right resistance, even if you have no cat, it will keep the voltage within its parameters and the ECU will not think anything is wrong, therefore no CEL.

[russiankid]

O2 sensors read in voltage up to .05 I believe. The voltage is determined by how much of certain exhaust properties that their are (i.e. carbon monoxide etc). If there is too much of said exhaust properties, the voltage goes higher, which then tells the ecu "ok theres something wrong here, I shouldn't be seeing this much voltage, the cat is bad" and it throws a light. If you put a resistor in line with the right resistance, even if you have no cat, it will keep the voltage within its parameters and the ECU will not think anything is wrong, therefore no CEL.

Some cars use the pre-cat and after cat O2 sensors to adjust the fuel maps accordingly. So if you try to trick the after cat O2 sensor, it may cause the car to run worse. Easier to just replace the O2 sensor.

[240sxDann]

Some cars use the pre-cat and after cat O2 sensors to adjust the fuel maps accordingly. So if you try to trick the after cat O2 sensor, it may cause the car to run worse. Easier to just replace the O2 sensor.

As far as I know, down stream O2 sensors are only to indicate whether or not the cat(s) are working properly. Upstream are for fuel control. But somebody correct me if I'm wrong.

[Erik]

there is a precat on the car.so im assuming there is a second o2 sensor.. I know the cat was bad, i dont know if the o2 sensor is yet. I need to get the cel cleared. As far as the resonator, i already have the 310 dollar catalytic converter. no point in that now, although that is good to know.

[russiankid]

Not all cars have an after cat sensor.

[240sxDann]

Right, all fuel injected cars have an upstream, but only some OBD1, and all OBDII cars have downstreams.

[Erik]

Not all cars have an after cat sensor.

i know my car does, its about 2 feet following the catalytic converter

[Erik]

the vibration sounds like its from the front of the car, although the scanner read a rear cat was bad and that was it. could it be the exhaust manifold possibly?

[240sxDann]

open the hood and rev it up at the throttle body and listen for it. Could be a ton of things.

[pinacup7]

O2 sensors read in voltage up to .05 I believe. The voltage is determined by how much of certain exhaust properties that their are (i.e. carbon monoxide etc). If there is too much of said exhaust properties, the voltage goes higher, which then tells the ecu "ok theres something wrong here, I shouldn't be seeing this much voltage, the cat is bad" and it throws a light. If you put a resistor in line with the right resistance, even if you have no cat, it will keep the voltage within its parameters and the ECU will not think anything is wrong, therefore no CEL.

This is mostly right. But o2 sensors only read oxygen.

As far as I know, down stream O2 sensors are only to indicate whether or not the cat(s) are working properly. Upstream are for fuel control. But somebody correct me if I'm wrong.
That is correct

[240sxDann]

yea I guess that would make sense....hence...."oxygen" sensor. LOL!