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Did you get a CEL after hollowing out the primary catalytic converter?

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  • No

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Discussion Starter #1
Since I bought the car, I have been experiencing what I believe is a catalytic converter issue. No CEL, no codes, recently did a tune-up with new Denso plugs, wires and Toyota cap/rotor. Also put in a new air filter, did a throttle body cleaning, put in a new Toyota fuel filter, replaced both o2 sensors, did an ECU reset, etc etc.

When the car is warm, it has a tough time accelerating on any kind of upward incline. And occasionally I can replicate a rattling at around 2000 RPM that sounds similar to beans in a can. It is NOT the engine itself making this noise because if I sit at a stop and rev it the noise can't be replicated, it's only when under load. Therefore based on these symptoms, I am starting to believe the primary catalytic converter may be broken or clogged and the chunks inside are causing this rattling noise.

There are a few options for this, one being a replacement catalytic converter but they are pricey at $200+. Another option is to get an OBX header and delete the primary cat in the process, however will this header bolt on to the factory or stock flex pipe that comes right after the primary cat? I really don't want to have to get custom exhaust work done. The last option would be to hollow out the primary cat and just throw it back on the car.

I've seen a few members have luck with doing this without getting a CEL as a result or by using a CEL cheater for the o2 sensor. So please answer the poll, if you will, to let me know if you had a CEL come on after doing this or if it did come on. Unfortunately I live in an area that hooks up an OBD2 scan tool during emissions testing so having a CEL on during an emissions check will fail me. As such, looking for the appropriate fix that is most cost effective. Some extra performance gained from it would be a plus.

-Matt
 

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Discussion Starter #4
So I hollowed out my primary cat on Saturday and as of now still no CEL. I've driven a couple hundred miles since then.
 

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So I hollowed out my primary cat on Saturday and as of now still no CEL. I've driven a couple hundred miles since then.

Did you fix the rattle?
 

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Makes you wonder the purpose of the secondary O2 sensor, if it can't detect a missing cat, what can it do? Announce that the sensor is bad? :)
 

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Makes you wonder the purpose of the secondary O2 sensor, if it can't detect a missing cat, what can it do? Announce that the sensor is bad? :)
I was working at mine yesterday for over fuelling and suspected 02 sensor is gone as there only is one on mine just in front of the cat, but no cel ever come on to say it was faulty so I unplugged it, started the rav and run it until normal operating temp and the cel light never illuminated. So why have the damn thing there if the ecu doesn't even recognise it missing even when its broke.
Unless I have to road test it to recognise its missing.
 

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I was working at mine yesterday for over fuelling and suspected 02 sensor is gone as there only is one on mine just in front of the cat, but no cel ever come on to say it was faulty so I unplugged it, started the rav and run it until normal operating temp and the cel light never illuminated. So why have the damn thing there if the ecu doesn't even recognise it missing even when its broke.
Unless I have to road test it to recognise its missing.

Most codes are a "two trip" code. The first time the PCM notices a fault, it logs it and sets a pending code. The next time the PCM sees the same fault, it will illuminate the MIL and change the code from pending to current. Some codes cannot be cleared by disconnecting the battery, and some codes will not illuminate the MIL by design.
 

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Thanks Fixit for the insight on how the pcm works.
I did check for codes by connecting the two pins in the diagnostic plug under the bonnet to get the codes but none were stored. I disconnected the plug for the lambda sensor and checked the ohms reading on the heater circuit and got 0.015 ohms when it should be 15.00 according to what I have read on the net. I take it fuel consumption would still be high if I drove it with the lambda sensor unplugged?.
regards
kev
 

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Discussion Starter #11
For what its worth, I also replaced the oxygen sensors with new Denso units not too long ago, and replaced the 3 front most exhaust gaskets when I removed the cat to hollow it out.

And the rattle isn't gone unfortunately, I actually believe its from my drivers side front CV axle. Low end pickup has improved a bit with the hollow cat, however. My exhaust system now comprises of the hollow cat, a secondary high flow cat and then 2.25" piping all the way back.
 

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Discussion Starter #15
Only when driving during a certain RPM range, won't make the noise when I sit and rev it to those same RPMs at idle. I did look at the axles not too long ago and they are original. The boots aren't torn but there is a little "sweating" on the outside.
 

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Doesn't sound like the cv,s matt unless in the early stages as they usually make noise at all speed ranges, whats it like turning full lock and moving in a circle slowly left and right ?, usually they crunch a bit and bang a bit if they are on the way out.
 

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Discussion Starter #17
It happens when moving straight mostly. What else could it be then? It's a light pinging or chattering. I sure as hell hope it's not the transaxle. :(
 

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It could be any number of things Matt is your car right or left hand drive as I cant see where your located?. Reason why is when you talk about the drivers side is that gearbox side or engine side?
 

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Discussion Starter #19
Left hand drive. It sounds like it's coming from right behind the firewall or foot well area on that side.
 

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The heat shield on my lower cat would rattle at some RPMs, mostly when driving.
A small tweak to the shield cured the problem on mine.
 
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