A few weeks ago I put a post about my cat possibly being dead but wasn't sure. That was the original cat, 12 years on the car.. 2000 honda accord btw 4cyl.. Anyway, had it replaced with a magnaflow OEM spec converter and when I shook the old one that was taken out things were all loose in there.. That thing was done..

Well, it's been three weeks on the magnaflow and I'm fairly certain it's dead and/or in the process of collapsing again.. The rattling isn't there yet this time but there is a weird slight groan when accelerating around 2500 rpm and then it goes away.. Thing is, that groan existed on day 1 of installing this cat but it seems to have gotten a bit louder.. I get the feeling it's in the process of collapsing again..

I replaced the O2 sensor in the cat with a new one from denso when the cat was replaced.. but the other O2 sensor is still the old one..

Among other things dying or dead, vapor canister or some leak in that exhaust system somewhere. replaced it with a junk yard canister but that didn't seem to solve the problem, the CEL was right back on and I presume that was the same code although didn't run the code yet.. 95k miles on the same time belt, oil leaks all over and I was told the valve cover gaskets need to be replaced, haven't done that yet.. does any of this collapse catalytic converters??

This car is just up and quitting on me after 220k miles.. I feel sad..

 

An exhaust leak can cause a convertor to fail, but the leak needs to be before the convertor...after it won't matter much as long as it's far enough behind the last O2 sensor. As far as you groan, who knows, maybe some exhaust harmonics due to the higher flow cat? Find the exhaust leak, get the DTC pulled so we know what we're working with and then report back.

 

Good advice from Dr. D.

In my experience folks get frustrated w/ a car when things fail, as they inevitably do. They use this to justify new car purchase, despite compelling economics that car repair is much cheaper than car replacement. That new car smell is mighty expensive!

good luck

 

new car?? lol nahh I don't have 200 for another catalytic converter replacement, let alone a new car.. i'm hoping this thing stays...

I guess I'll have that smoke test done and try to figure out where the leak is.. probably going to take a couple of weeks though so I can wait til my exams get done.. I'll keep you guys updated..

in the meantime, I'll just keep driving the car as it is hoping all is well..

 

The exhaust leak doesn't necessarily cause the converter to actually fail. It just screws up the O2 sensor measurement so the ECU "THINKS" the converter is bad.

Oxygen sensors actually measure the oxygen DIFFERENCE inside vs/ outside. So exhaust blowing onto the outside of the O2 sensor will throw off the measurement.

 

yeah but that's the thing though, the ECU doesn't think it's bad.. The check engine light says nothing about bad O2 sensors or bad catalytic converter, it never gave me any of those codes.. even with the old one rattling, it still didn't give me a code.. The only code I've is a P1457, which is being a pain in the ***..

I was told that the P1457 might be coming from an exhaust leak.. The catalytic converter, after being replaced, seems to run fine but that little groan got more noticeable.. It's not rattling yet like the old one but something just feels not as good as it did on the first day of replacing it..

Anyway, last final exam got done yesterday, so I'll try to go out today and get that smoke test done for the P1457, which may determine if there's an exhaust leak.. I'll keep you guys updated on what happens with that smoke test..

Btw, I noticed something off topic and random yesterday, there's smoke coming out of my engine bay, very little but pretty noticeable, as if something is burning.. Couldn't figure it out in the dark last night but there was smoke right by the passenger side headlight/intake from what I could see in the dark.. Seemed to drive fine though, drove like a 100 miles to school and back, no worries, the temps seem normal..

 

Oh boy, I wish I'd asked right at the beginning what was the code number.
P1457 is EVAP leak in the canister system. Has NOTHING to do with the cat-converter.

Look in the DIY section for a post by me about EVAP leaks (earch for "P1457"). There's a couple solenoid valves you can check, and of course look for rotted-rubber vacuum hoses down around the canister. Also a leak in the fuel-vent tube that runs up to the engine compartment. A bad vent-shut valve is a common problem, but it could also be the EVAP purge valve in the engine bay.

 

I'll have to find said evap purge valve in the engine bay.. I replaced the whole thing with the canister (although with another junkyard one).. So you're saying this has nothing to do with the catalytic converter right?? So the groan from that converter is just because its aftermarket (presumably)??

I'll check out your EVAP leaks DIY..

Btw, that burning smell, noticed serious smoke this morning while driving back from KFC (had a craving).. That hose that goes straight form the radiator seems to be leaking. There's liquid for sure, it's not green, looks like water.. Dropped it off at the gas station so the guy could tell me whats burning and/or leaking..

 

Evap purge valve is bolted onto the intake manifold, #8 in this picture.


The vent-shut valve (common failure), is bolted onto the outboard end of the EVAP canister. You would probably leave the one that was attached to the junkyard EVAP can. Get some jumper wires & apply battery-voltage to that solenoid. When mine went bad, it didn't even click when I powered it directly.

 

oh cool, thanks for that diagram.. alright so I'll try to take a look at that today and see if I can figure it out..

Just found out yesterday I gotta replace my radiator and can't be driving the car.. So gotta figure out how to do that first..

I'll keep you updated on what I find with the vent-shut valve.. And yeah the junkyard part was the whole thing, didn't change the vent shut valve, it came with the canister..