Anybody ever remove the catalytics on a 1fz-fe in the intrest of less restiction? If so what of the O2 sensor? Am I going to get flamed for asking a super noob question?
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Cut the cats?
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Until '95, all LCs O2 sensors were upstream of the cats, so things wouldn't be affected.
In my case since I don't go off road, I cut right after the first sensor and replaced both OEM cats with one Magnaflow Hi flow cat (part # 43009 OBD 2) and took whole day from morning until nite time to do custom mandrel bent, straight 3 inch pipe all the way to the back.Now Instead the factory pipe 2.25 inch go up over the rear axle, crimped but I did straight pipe under neath it all the way to the back with Hi flow JDM muffler, will post the pic this weekend 
Ohh and no resonator at all except the JDM muffler.
except the JDM muffler.
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Anybody ever remove the catalytics on a 1fz-fe in the intrest of less restiction? If so what of the O2 sensor? Am I going to get flamed for asking a super noob question?
You can get dummy 02 sensors for after the cat from Summit or Jegs. It will keep your dummy light from coming on.
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ok, Im working with a 97. 1: Does anyone anticipate a benifit from removing the cats? 2: If one were to do this what would you do with the down stream O2 so as not to mess with OBD2? Could you simply have the exaust pipe tapped and mount the O2 there?
If I were in your shoes, I would straight pipe the cats, and run dummy O2 sensors instead of the downstream sensors.
There would probably be some benefit by eliminating the cat but making other changes would increase the benefit you realize. It is the sum of all changes that can be greater than adding individual gains. Synergism or something like that.
You would leave the pipe alone and run a dummy sensor. Your downstream sensor would give you a bad reading without a cat.
I do not think you will gian much if any, the OEM cats are already high flow, you can see right through them. they are made out of a solid grid, picture a window screen extruded into 3d, the older kind that were filled with a bunch of coated spheres were restrictive.
Most rear O2 simulators put a constant 450mv signal for the rear 02 (Ecu reads this as no correction to basic fuel setting necessary, or more specifically, short term fuel compensation needs no baseline correction). This means you have effectively disabled the rear o2 sensor circuit. The problem with this is that some computers look for a variable signal, and will trigger a rear 02 code. I'm pretty sure the Toyota 1FEFZ OBDII doesn't look for a variable signal, so this should work fine.
I haven't done a lot of testing with this mod, because the cars I work on look for a variable signal. I know there are a lot of Ford and chevy guys that run these without issue. And the toyota OBDII ECU for the LC is as simple minded.
There are extenders available as well that take the rear 02 out of the exhaust stream, reducing the effectiveness of the sampling. The problem I see with that is there really isn't room for increasing 02 height in the LC's, and it would require a switch to a bung type o2 sensor plate.
A rather simple and inexpensive mod, that I'm sure keeps the boys at the EPA in a chronic tachycardic state. Did I mention it's illegal to install these?
ST
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I think the guy with the vette could afford the penalty and being from Ohio I don't think he has to worry about it anyway.
I think you would be ok legally to use these offroad only(meaning not registered for the street). Not sure though.
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It's only illegal if you get caught. I'm in the process of swapping my dual cats to a single cat so I can run the exhaust over the frame. This will cure any problem I have with that rear O2 sensor. Besides, the sensor is on top of the exhaust, inside the frame. I think that if on of the genius' at DEQ happen to find it, it will visually look correct. Let me know if this is an unreasonable thought process. TIA
It's illegal, I didn't say not to do it! There is no 'offroad' clause on o2 sensors. If it has a legal plate, it needs emissions equipment intact. This requirement is starting to trickle over to racing as well.
The Magnaflow 59929 (3in in 3in out - 11in long) universal cat mentioned in another thread looks to be pretty good and could eliminate all the headaches, it's EPA legal, uses the metal matrix technology in race cars, and is reasonably priced (104USD at hotexhaust.com)
And did I mention deleting the cat is illegal
ST
The Magnaflow 59929 (3in in 3in out - 11in long) universal cat mentioned in another thread looks to be pretty good and could eliminate all the headaches, it's EPA legal, uses the metal matrix technology in race cars, and is reasonably priced (104USD at hotexhaust.com)
And did I mention deleting the cat is illegal
ST
I wasn't planning on deleting both cats, just one of them. I'm just worried that I'm going to throw a code because of it. So, technically, it's illegal. But according to a visual inspection and OBD scan everything looks fine.