De-cat exhaust system

[aucorium]

Hi Guys

Im thinking of doing a De-cat on my Yaris , and was wonder if anyone has done one with success , is there a better throttle response and what is the power increase all be it very small.

thanks !

[eTiMaGo]

The Nitto midpipes that I sold and Garm now does, has no cats, just resonators for a nice sound. There was definitely an increase in power when I installed mine, but then I never dyno'ed it so I cannot tell you how much.

Only problem you might have is with the oxygen sensor, it might throw a malfunction light if it detects there is no catalyser action going on. This can be mostly solved using a spacer like a spark plug anti-fouler for the rear O2 sensor.

[aucorium]

The Nitto midpipes that I sold and Garm now does, has no cats, just resonators for a nice sound. There was definitely an increase in power when I installed mine, but then I never dyno'ed it so I cannot tell you how much.

Only problem you might have is with the oxygen sensor, it might throw a malfunction light if it detects there is no catalyser action going on. This can be mostly solved using a spacer like a spark plug anti-fouler for the rear O2 sensor.


hey bro

AWESOME !! thanks for the info , yeah , i would need a lambna sensor delete , i know they did it to my buddies honda fit , and his seems to be running well.

[aucorium]

how is the system on your car setup ? does it have one of those on ?

[eTiMaGo]

I just have a spacer on mine, and never had a CEL :smile:

[PETERPOOP]

I have 2.25" header back exhaust. No cats and a 18" resonator. I am also boosted. I am going to be putting on a hi flow cat tomorrow. At first I was running a magnaflow muffler and it was LOUD, but now I switched mufflers and it's as loud as an axleback (even with no cats). I'm still going to put on the hi flow muffler just to quiet it down a little more and get rid of that smell. I can feel a sense of free flowing and non restrictiveness now. However, like I said earlier, I am boosted.

Oh yah, and to your question, no great throttle response (atleast in lower RPMs). I lost some torque by going with this exhaust setup. However, my supercharger picks up the slack.

edit: I also used the o2 anti fouler for the secondary sensor. I have no CEL because of it. However, once I put my high flow cat on, I'm going to take it off.

[aucorium]

I just have a spacer on mine, and never had a CEL :smile:

thats good news ! so all that the origional sensor does is regulate emmsions , the one after the cat i mean ,it cant effect richness or being lean etc ?

[aucorium]

I have 2.25" header back exhaust. No cats and a 18" resonator. I am also boosted. I am going to be putting on a hi flow cat tomorrow. At first I was running a magnaflow muffler and it was LOUD, but now I switched mufflers and it's as loud as an axleback (even with no cats). I'm still going to put on the hi flow muffler just to quiet it down a little more and get rid of that smell. I can feel a sense of free flowing and non restrictiveness now. However, like I said earlier, I am boosted.

Oh yah, and to your question, no great throttle response (atleast in lower RPMs). I lost some torque by going with this exhaust setup. However, my supercharger picks up the slack.

edit: I also used the o2 anti fouler for the secondary sensor. I have no CEL because of it. However, once I put my high flow cat on, I'm going to take it off.


ok cool , shot for the info buddy.

the smell you getting is because the cat is gone ?

i dont mind to much if its a little louder , so long as the car runs better with the cat gone , my little 1300cc can do with every little bit of power , no matter how small , LOL

[cali yaris]

This is the anti-fouler they are talking about:

http://shop.microimageonline.com/images/1225920319290-1369777280.jpg

The second O2 sensor (you have two sensors on the exhaust side, one on the manifold and one on the midpipe) looks for cat failure. The anti-fouler moves the sensor away from the exhaust stream, fooling it into thinking the cats are on the car.

[PETERPOOP]

it cant effect richness or being lean etc ?

I'm not sure about this. However, since I have a hi flow cat on now, I don't think I need the anti fouler on anymore. Once I get a scangauge, I will be experimenting with and without the o2 sensor on.

[eTiMaGo]

nah the air/fuel ratio is determined by the front sensor, as mentioned by Garm, the rear one is just t check that the cat is functioning (basically checking if the gases coming our of the cat is cleaner than the gases going in), so if you don't have a cat, the spacer will shield the sensor a little bit, so it will seem to have a cleaner airflow.

[aucorium]

This is the anti-fouler they are talking about:

http://shop.microimageonline.com/images/1225920319290-1369777280.jpg

The second O2 sensor (you have two sensors on the exhaust side, one on the manifold and one on the midpipe) looks for cat failure. The anti-fouler moves the sensor away from the exhaust stream, fooling it into thinking the cats are on the car.

ahhh i see ! makes sense , how much is the fouler ?

[aucorium]

nah the air/fuel ratio is determined by the front sensor, as mentioned by Garm, the rear one is just t check that the cat is functioning (basically checking if the gases coming our of the cat is cleaner than the gases going in), so if you don't have a cat, the spacer will shield the sensor a little bit, so it will seem to have a cleaner airflow.


ahh ok cool !!! no i see how it works , thanks buddy! now i know it can be done.:headbang: next on the list after my Teins arrive and is fitted , De-cat.