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Discussion Starter · #1 ·
Right now i've got the stock exhaust manifolds with the catalysts drilled/knocked out and have some magnaflow cats installed in my b pipes with the nismo "cat" back true dual exhaust with dual magnaflow mufflers since the nismo muffler welds cracked bad. So with my SAS the b pipe magnaflow cats are going to be in the way when I get a bigger front driveshaft, since theirs so much room right in front of the mufflers can I just install the cats before the mufflers and extend the O2 sensor harness or would there be any adverse effects to having the cats so far back?

Questions, comments, ideas are welcome.
 

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Catalyist effiency depends on heat, it is most effiecient at 1600 deg f inside the cat. Keeping the cat that hot that far from engine i dont think will work. You probably get codes p0430/p0420 which are effiency codes for the cat all the time.The ecm looks at front 02 sensor and compares is to the rear 02 sensor to monitor the cats effiency. Heat is why every manafacture is putting the cats so close to engine now and making the cat material so thin to heat up faster, durable not at all. But the government and citizens want fewer emissions and thats what we get. Not the manafacture`s decision
 

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Discussion Starter · #5 ·
Do you have cats at all on your truck? I've heard spark plug defoulers with the ends drilled out will fool the computer, i had an oxygen sensor simulator last year before i put cats back in and it worked but didnt, it kept the light off but my ready codes for the oxygen sensor and cat wouldnt go ready. Any insight on that??
 

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Do you have cats at all on your truck? I've heard spark plug defoulers with the ends drilled out will fool the computer, i had an oxygen sensor simulator last year before i put cats back in and it worked but didnt, it kept the light off but my ready codes for the oxygen sensor and cat wouldnt go ready. Any insight on that??
I actually just re-installed my cats and 02 sensors. I hard reset the computer, drove like a bat outta hell til my monitors turned off and parked it for the night. The next morning I hauled azz over to the smog shop and it passed!!! On the way home I got a CEL PO420 LOL!!

The 02 sensor actually measures how much oxygen it takes to burn off the fuel in the exhaust. I too have heard that pulling it out of the exhaust stream a little will fool it into thinking the cats are working better.

My smog guy said it barely passed. With the readings I was getting it was like the cats were going bad. I believe it was said above that the cats don't get hot enough to work correctly, I really think that is true.

I tried the URD 02 sim and it just made my computer throw a code saying the front 02's were bad???!!!! It's crazy how sensitive the Toyota computer is!! I'll try the antifouler one of these days.







So when you had the simulators on your truck the monitor wouldn't run?
 

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Discussion Starter · #7 ·
Lol that happened to me last year, right after i left the smog shop the light came on, but it was just a freak coincidence because it was actually the heater element in one of my front A/F sensors that went bad, which actually screw my mpgs too because the sensor wasn't warming up enough to get an accurate reading.
 

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Lol that happened to me last year, right after i left the smog shop the light came on, but it was just a freak coincidence because it was actually the heater element in one of my front A/F sensors that went bad, which actually screw my mpgs too because the sensor wasn't warming up enough to get an accurate reading.
haha, it's crazy how everything has to be just so and seems so complicated, and when it is just right how simple it all is over being having a carburetor.

But it's interesting what you said before: When you ran a simulator did the monitors for the rear 02 sensors never run?
 

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Discussion Starter · #9 ·
No the monitors ran I guess just the simulator wouldn't do the right sequence that the computer wanted to see from the rear sensors, but it must have seen enough to not trip the light, I drove it like that for probably 800 miles with no light but with 2 not readys as well.
 

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No the monitors ran I guess just the simulator wouldn't do the right sequence that the computer wanted to see from the rear sensors, but it must have seen enough to not trip the light, I drove it like that for probably 800 miles with no light but with 2 not readys as well.
ya, seems when you run simulators they don't 'switch' as it would if it weren't being simulated. Plus I think that they have to switch in conjunction with the front sensors or it throws off the ECU and it gets mad. LOL

So here is where I get schooled: What do you mean by "not ready's"?
 

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I think the cats close to the manifolds are intended to decrease emissions right after startup. Not sure, but I don't think it matters after you are warmed up, cuz the downstream cats get plenty hot. A little extra cold start emissions seems like a good trade for not getting cat grit back sucked into the engine.

"Many vehicles have a pre-catalyst located close to the engine's exhaust manifold. This unit heats up quickly due to its proximity to the engine, and reduces cold-engine emissions by burning off hydrocarbons from the extra-rich mixture used in a cold engine."

Catalytic converter - Wikipedia, the free encyclopedia
 
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