I making a manifold and want to replace the stock cats with hi flow cats. What kind are you guys useing that will still keep the CEL off and keep the o2s happy?

Thanks.

 

You looking for something CARB approved?

 

Doesn't have to be carb approved just a cat that will "work" like the stock one in that the o2 sensor will be happy and won't trigger a CEL.

 

My bro has a 2.5 in magnaflow hign flow cat on his type r and he has no cell

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by danielm3 &raquo;</TD></TR><TR><TD CLASS="quote">Doesn't have to be carb approved just a cat that will "work" like the stock one in that the o2 sensor will be happy and won't trigger a CEL. </TD></TR></TABLE>

What vehicle and header?

 

I've seen many people run a spacer on the secondary o2 to keep it from "tripping".

The reason it sets a code is b/c the reading the 2nd o2 sees is the same from the first o2. It should be different so it knows the cat is working properly.

Spacing the 2nd o2 out away from the flow varies the voltage just enough it works.

There is a thread on here I beleive about it. You can get the spacer things @ autozone/advance

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ExVtec &raquo;</TD></TR><TR><TD CLASS="quote">I've seen many people run a spacer on the secondary o2 to keep it from "tripping".

The reason it sets a code is b/c the reading the 2nd o2 sees is the same from the first o2. It should be different so it knows the cat is working properly.

Spacing the 2nd o2 out away from the flow varies the voltage just enough it works.

There is a thread on here I beleive about it. You can get the spacer things @ autozone/advance


</TD></TR></TABLE>

The spacer thing doesn't always work and didn't in this case.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SMSP &raquo;</TD></TR><TR><TD CLASS="quote">

What vehicle and header?</TD></TR></TABLE>

IS250 and my own header.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by danielm3 &raquo;</TD></TR><TR><TD CLASS="quote">

The spacer thing doesn't always work and didn't in this case.</TD></TR></TABLE>

True, nothing works all the time, but it's a cheap and easy fix that is always worth a try.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by danielm3 &raquo;</TD></TR><TR><TD CLASS="quote">

The spacer thing doesn't always work and didn't in this case.</TD></TR></TABLE>

really? I use anti-foulers on test pipes all of the time!

 

about 5yrs back, we installed some cel eliminators on a friends mustang, i think its just a sort of jumper wire harness that goes between the plug and the sensor. not sure if that helps though.

 

antifowlers ftw.

 

carsound (magnaflow) cats claim to be OBD-II compliant, have you tried those?

 

The electronics on the newer cars are much more sensitive than the older early obd2 stuff. They actually use the secondary o2 readings to adjust a/f ratio to increase catalyst efficiency and lengthen the life of the cat.

I would think a high quality high flow cat would work and keep the computer happy, but i won't if there's really any power to be had over the oem lexus cat? My guess is not much if any on an N/A application.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">The electronics on the newer cars are much more sensitive than the older early obd2 stuff. They actually use the secondary o2 readings to adjust a/f ratio to increase catalyst efficiency and lengthen the life of the cat.

I would think a high quality high flow cat would work and keep the computer happy, but i won't if there's really any power to be had over the oem lexus cat? My guess is not much if any on an N/A application. </TD></TR></TABLE>

I cant imagine that the factory manifolds with cats integrated into them are very good for making power.

sounds to me like he's just trying to make a good package deal with his header that is bolt-on for the customer.

 

I understand what he's trying to do. There's not many aftermarket cats out there that are OEM quality and OEM's have really started paying a lot of attention to performance on a lot of the new cars. I just said i don't think there's much power to be found over the oem cat. I may be wrong, until someone tests it we'll never know.

If the cats are integrated into the oem header, then you don't have much of a choice for a bolt on application. I can tell you this though, don't buy a $100 cat and expect oem catalyst performance out of it. Most oem cats are close to $1k. Hell, the scrap guys that come by my shop for metal give me $125 for an OEM cat of any condition!

 

I'm using a large Matgnaflow 3" in/out cat with a rich aftermarket tune and I don't have CELs. It was not a cheap cat though, and is OBDII compliant.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">The electronics on the newer cars are much more sensitive than the older early obd2 stuff. They actually use the secondary o2 readings to adjust a/f ratio to increase catalyst efficiency and lengthen the life of the cat.

I would think a high quality high flow cat would work and keep the computer happy, but i won't if there's really any power to be had over the oem lexus cat? My guess is not much if any on an N/A application. </TD></TR></TABLE>

Thanks Tony. The OEM cats are in the stock headers, I am not trying to make a bolt on thing. I sell IS250 headers and one of customers wants to keep the CATs in, so I have to find some that will not trigger the CEL so I don't have to use any kind of sim.

 

Is the diameter ok on the stock ones? Can they be cut off and reused?