cat removal

Audacity Racing · Post by **Audacity Racing** » Fri Jul 15, 2005 6:39 pm

so now that my woo is going full race, i was wondering if anyone has removed the cats and tried the o2 simulators or fouler kits. i was reading on some honda and evo sites that it's a 4 dollar fix to take out the cel. has anyone tried this with a woo?

i'm saving up for the aem universal ecu kit, but until then, i need the stock ecu to run the car for me. i was gonna run mega-squirt, but the aem is a WAY more powerful option.

check this out... http://forums.evolutionm.net/showthread ... hlight=ses

KnightWalace · Post by **KnightWalace** » Fri Jul 15, 2005 8:49 pm

I've done it in my lancer as i put the RRM downpipe in about 600 miles ago... no cel yet.

Not sayign taht it won't throw every now and again.. but it won't be constantly on.

Audacity Racing · Post by **Audacity Racing** » Fri Jul 15, 2005 8:53 pm

would it work to do that on both o2's?

Brian5475E · Post by **Brian5475E** » Fri Jul 15, 2005 9:33 pm

you need the 1st O2 sensor close to the engine, that measures how your fuel is burning. Too far away from the engine could cause problems

Audacity Racing · Post by **Audacity Racing** » Fri Jul 15, 2005 9:35 pm

i'm stupid... as per the norm... the 1st sensor is before the cat, so it doesn't matter... i'm good

MMamdouh · Post by **MMamdouh** » Fri Jul 15, 2005 11:15 pm

some people said that you have to fool with the signal of the second O2 sensor to avoid the CEL... you see if both O2 sensor give the same reading to the ECU then the ECU will think you have a faulty CAT and throw a CEL.

the second sensor should have a risistor or so in its circuit to fool the signal and make it read less O2 than the first so that you don't have the CEL... i am not sure of the specs of the risdistance you need so you better get that from a more experianced person with this stuff.

MMamdouh

KnightWalace · Post by **KnightWalace** » Sat Jul 16, 2005 12:32 am

ididn't need a resister or anything and mine is running fine.

I don't know if the daewoo would see a different set up.

Brian5475E · Post by **Brian5475E** » Sat Jul 16, 2005 1:52 am

I saw somewhere if you use a deeper o2 bung for the rear one it will hold the O2 sensor out of the exhaust gases. So it will read less and no CEL

Audacity Racing · Post by **Audacity Racing** » Sat Jul 16, 2005 1:55 am

Brian5475E wrote:I saw somewhere if you use a deeper o2 bung for the rear one it will hold the O2 sensor out of the exhaust gases. So it will read less and no CEL

that's what that other forum link i posted was about

www.forenzamotorsports.co · Sat Jul 16, 2005 2:45 am

I understand going free flow but some back pressure is crucial in the 0-30 MPH range. I have seen especially with base Hondas, people increase 0-60 time due to the reduction in torque being a greater loss than the top end horse power gained "super free flowing" that MAY not actually come till almost 60-85 MPH. I may plan on losing the resonator and maybe doing a header or at least gasket & port match my stock manifold but going no cat may cost some torque which equals acceleration.

Scott

Audacity Racing · Post by **Audacity Racing** » Sat Jul 16, 2005 3:21 am

i'm going turbo... twins at that... it's gonna be straight pipes except for the turbos, with an anti-lag (shoot some fire!)

MMamdouh · Post by **MMamdouh** » Sat Jul 16, 2005 11:56 am

i already removed my CAT and one fellow Woo owner drove my car and told me i lack acceleration at low RPM but it is great at high RPM... could this be due to lack of back pressure? i mean the low acc. at low RPM part?

MMamdouh

www.forenzamotorsports.co · Sat Jul 16, 2005 4:13 pm

Yes it is possible. Under NA situations removing all back pressure will decrease torque and bottom end response. It may pep up, and 4500 rpm plus may seem quicker on the top end but you can counter act it by losses in the low end....bogging down etc. That is why dyno charts do not always reflect actual 0-60 info. You can do a mod and add HP some where in the band...loose some elsewhere and the true net effect could be half of what you think.

Your cat, in a very free flowing set up is restrictive but in some cases is all that is left with restriction to create back pressure. So you could see a HP increase at high RPM with no cat but a loss in HP and torque in the low range which is where we cruise around going to school, work etc..most of the time.

Scott

Audacity Racing · Post by **Audacity Racing** » Sat Jul 16, 2005 4:15 pm

hey mmamdouh, where did you get that pipe to replace your cat, and roughly how much did it cost you? it looks good...

MMamdouh · Post by **MMamdouh** » Sun Jul 17, 2005 12:05 pm

i got it from a local shop downtown and it costs 40 LE (6.90 USD).

MMamdouh