Has anyone driven t4r without Catalytic converter

[dclark2171]

I'm not going to try, plus its illegal. However, this car buff client was raving the performance of his Honda Pilot by removing the CC. He stated you can purchase a "fake" Oxygen sensor that will fool the computer and not make dash lights come on. He says his pilot runs like a sports car (i'm sure he's exaggerating).There's so many people here that mod their own 4 Runners, I'm sure somebody has tried. Just curious of the performance increase

 

[Runn4est]

Never done it in a T4R, but in my experience, the results are negligible. If you want to stay legal, you can buy a hi-flow cat, but again, I think you'll find it was not worth the $.

 

[Hellamatic]

You can buy O2 sensor simulators. However, they will only provide a fixed feedback signal to the PID in the computer. I can't imagine it would run that great.

 

[MSinDC]

I don't know about the performance after taking a CC off, but I know the fake oxygen sensors exist because I put one on my 3rd gen.

I had a California spec'd 3rd gen (or so I believed from my internet research) that apparently had tighter tolerances on emissions...i threw a code after owning the truck for about 3 years that the 2 bank sensor was out, so I just replaced both sensors since the truck was getting up in miles. The CEL went away for about 2 months, then came back same code. After researching it appeared a ton of 3rd gens had the same problem, so much so that URD developed a fake sensor to turn off the CEL's.

Probably not the best idea, but I needed to get rid of the CEL's so I could pass "emissions" in DC.

 

[Bootleg]

Removing the cat is going to significantly increase the amount of exhaust gases that flow through your exhaust system and reduce the back pressure. You may notice a small gain in top end power but without a dyno tune you aren’t going to get any significant or worthwhile gains. Plus you have to install a dummy cat to pass the visual inspection and on O2 simulator to keep the ECU fooled and the CEL off. It’s simply not worth it on most naturally aspirated cars. Don't even bother. On a turbo car like my WRX or a rotary you can get some nice gains, but that’s with a proper engine tune.

And to dispel any oxygen sensor myths, the O2 sensor that would cause a CEL with a catalytic converter has one purpose and that is to determine if the emissions equipment is functioning correctly. This sensor is the one directly after the catalytic converters. The primary O2 sensor is before the catalytic converters so that it can accurately determine air/fuel ratios and make adjustments accordingly. If the primary is bad then yes, you will run very poorly and in limp mode. If the secondary is bad then you’ll get an annoying light and fail inspections.

 

[oljedi11950]

Urd y-pipe & rear-cat delete . Just did a flowmaster super 70ii . Nv we don't have visual so only hookup to ecu & if no cel all good . I have the sim in case but so far no cel . My 2cts

 

[flyinhawaiian01]

LOL!

Just having this same talk about cats and headers (mostly headers though) over on the 1st gen side!

Not sure about the 5th gen, but a 22RE 4 cylinder, no cat combined with a quality header and a good exhaust system not only gives a nice gain in performance, it also increases mpg by almost 2 points!

If I can keep out of the gas pedal, and keep my truck under 65mph, I can get 21-22mpg on the highway, this is with 35's!

I also have a "hi flow" cat for the truck, and while its on, I notice the vehicle is slightly less peppy and sluggish when I get on it (which is a lot when you have 4 cylinders and 35" tires, even with gears!), but not as bad as a stock cat.

As for the 5th gen, there's just too much ecu stuff going on to even bother with it. Toyota uses wideband sensors now, which is calibrated by receiving data from the rear 02 sensor, and the only company I'd suggest would be Underdog racing, but have no experience with them, so don't take my word for gospel!

Ahh, the good ol' days, when you could just cut the cat out and race your friends! They'd all be wondering why you just pull away from 'em when they have the same damned truck you have!!!:gun5:

 

[fyremanpat]

I put LT headers on my 13 Tacoma, which got rid of the cats. I used URD O2 sims. You WILL lose bottom end power but will gain top end. You will gain a MPG or two also. I would go with a hi flow cat and get the best of both worlds if I were you.

 

[Swarty]

Pre cats are the issue

I'm not going to try, plus its illegal. However, this car buff client was raving the performance of his Honda Pilot by removing the CC. He stated you can purchase a "fake" Oxygen sensor that will fool the computer and not make dash lights come on. He says his pilot runs like a sports car (i'm sure he's exaggerating).There's so many people here that mod their own 4 Runners, I'm sure somebody has tried. Just curious of the performance increase

The precats are the choke point on the 4runner exhaust.
You can get a performance header that removes the precats, this will get you more low end especially if you use equal length headers. You will need a sensor mimic for this which URD sells.
I like URD's design and will prob grab one eventualy:
Equal Length headers

Also the idea that you need a chip to get the power gains is not true with modern engines that have VVT on intake and exhaust. The system is really smart and can handle the difference provided by the headers. URD got 17 HP and 30 ft-lbs on the Tacoma with the stock ECU and rear cats intact. I did this on my MR2 Spyder and it rocked. Plus the sound of equal length headers is sweet, not louder just deeper and more "chuggy".

I'd like to do the header and then just reroute the y-pipe to go behind the transfer case instead of over it, keep the main cats which seem to be pretty high flow. I looked at URDs Y-pipe but they didn't pick the best path for the 4runner because they didn't want to replace the location of the connecting flange to the muffler.