Zero Dollar Mods

[kwiktsi]

Re: Guttin the cat

I believe there are 2 oxygen sensors on this car, one after each cat. Both sensors are hooked into the ECU, and are used as feedback to adjust the mixture. Its been awhile since I took my combustion class, so I forget the chemical reactions that occur at the catalyst and the effect on oxygen levels if its missing(I think higher).

Anyhow, I would guess that since the front cat is no longer doing its thing, the ECU may get confused and improperly adjust the mixture. If the ECU's range of adjustment is large enough, you could end up with some bad results. If its significantly too lean, you stand a chance of frying your valves - too rich and you get deposits, etc.

Just my 2 cents.

Remember, there is no such thing as a free lunch.

One is on the turbo exhaust outlet and it used for mixture control. The second is after the first cat (from memory) and is only used to monitor the cat's effeciency. When the cat goes bad, the O2 sees a problem and throws a CEL for it. It does nothing for mixture control.

As for resetting the light- it will come back on .. I gutted my cats a while back and didn't get a light for over 1200 miles!!! My driving had a lot to do with it too- I am always on and off the throttle, didn't get a chance to do a check for it probably. Once I hit a steady 65 in traffinc for 11 miles on my way to FL- bling there is was .. I now have my new exhaust with free flow cat to resolve that .
Joe
PS- You can probably use an O2 simulator in place of the rear o2 to prevent the light.

 

[eeterp]

i still dont see why hackin a lil on airbox and exhaust mods will void his cars warranty????? would a k-n filter void our warranty as well??

void warrenty? probably not.

against federal law? you bet your ass. modifying/removing pollution control devices before the car reaches 60,000miles could land you a $2,500 fine.

That said, nice free mods. The only thing it cost was time. Cats=backpressure=BAD for turbo cars. less backpressure=more power.

 

[Emode]

so joe,

now with your free flow cat, do you use the stock o2 sensor in the same place as before ?

 

[Emode]

That said, nice free mods. The only thing it cost was time. Cats=backpressure=BAD for turbo cars. less backpressure=more power. [/B][/QUOTE]

Yes, before i say this, i will remind everyone im still a novice when it come4s to this, but i think a lot of the low rpm stuttering and hesitation was because our cars are so chowked up on both ends. Now that it can breath a little better, and is able to get rid of the backpressure more efficiently, the problem is almost completely gone. All my clutch engages are now much smoother and i feel the power catching quicker.

Also , correct me if im wrong, but i now think our turbos spool up somewhere around 1500 rpms. I can really here the air start to move, and if i let off the throttle from 1500 to 2000, a can here the bypass releasing pressure. Although this might not have been happening until i fredup the pressure.

Any thoughts?

 

[kwiktsi]

so joe,

now with your free flow cat, do you use the stock o2 sensor in the same place as before ?

Kind of.. With my 3" exhaust, the cat is now after the crossmember/brace instead of under the motor, so I had to extend the O2 sensor wires to put it after the cat.. If you are familiar with what your exhaust looks like, you can make out the relocated cat in this pic.
Joe

 

[kwiktsi]

That said, nice free mods. The only thing it cost was time. Cats=backpressure=BAD for turbo cars. less backpressure=more power.

Yes, before i say this, i will remind everyone im still a novice when it come4s to this, but i think a lot of the low rpm stuttering and hesitation was because our cars are so chowked up on both ends. Now that it can breath a little better, and is able to get rid of the backpressure more efficiently, the problem is almost completely gone.

Any thoughts? [/B][/QUOTE]

Close- the stutter/stumble/falling on it's face is due to crappy ECU mapping.. Choking it up with a restrictive air box, 2 cats and a resonator don't help matters any .. By freeing up the intake and exhaust, you add more air to an overly rich mixture- not to mention turbo cars love to breathe also- so it is a plus regardless.

Even with my intake, exhaust and 12 psi (in FL), my car was still too rich and I had to pull fuel from it!!!

Bottom line, flow is good regardless, better when there is too much fuel and you need more air .

Joe