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Best fix for front cat?

Discussion in '1st Gen. Tacomas (1995-2004)' started by txironhead, Oct 28, 2012.

  1. Oct 28, 2012 at 10:15 AM

    txironhead [OP] Member

    Oct 24, 2011
    '99 Tacoma SR5 Ext. cab 2wd
    Brush guard, aftermarket cruise control
    I'm in Texas, but I have a Cali emission truck. The CEL is on, code is front bank cat. Yep, the expensive one on the exhaust manifold. Truck is a 1999 Tacoma 2wd ext. cab 2.4l SR5. Bone stock.

    I've been told that the aftermarket manifold cats are only good for a couple of years and still run $350-400. Dealer wants $1200 for factory. I do live in an emissions county, but they don't do a visual check. Worst case, I can get it inspected one way or another. However, I have no power until it warms up completely and even then it's sluggish.

    The original plan was to install a header and O2 emulator. Then I read conflicting posts about the sensors. Some say that there's a sensor before and after the second cat and I can just install the header and be done with it. Some say there's a sensor installed in the first cat that has to jive with what the computer's reading from the other sensors. A local guy said he just wired in a couple of resistors from Radio Shack and it worked. Yet another local said to take the front cat off, beat the brick out of it and reinstall it.

    I'm all for saving the planet, but I don't have the money to play by CARB's rules and since I'm not in Cali I shouldn't have to. If it were as simple as bolting on a 49-state manifold I'd do it, but I need to make sure the computer's happy. My main goal is to get the truck running the way it should be.

    So is there anyone out there that has successfully eliminated the front cat on a 2.4l and would like to share their secrets?
  2. Oct 28, 2012 at 7:05 PM

    Dick4x4 Well-Known Member

    Sep 22, 2012
    2012 4x4 2.7 Auto
    On OBD-1 systems, 95 and before, there was only one 02 sensor. 95.5 and after are OBD-2, that means they have the "news" standardized 16 pins under the dash and for some other things that also mean they have 2 O2 sensor.

    The first that is before the cat will tell your engine ecu, when in close loop (warmed up and other parameter like 75% less throttle and cruising) to put less or more gas to keep the stochiometric blend of 14.7:1... That makes your engine work right.

    The second sensor after the cat is telling to the system if the cat makes his job or no.

    Could you post a picture of the front section of your exaust? I'm not familair with the cali emission truck but I'm sure there's not a lot of difference with our system here.
  3. Oct 28, 2012 at 11:35 PM

    austinramsay Well-Known Member

    Apr 5, 2012
    First Name:
    Yuma, Arizona
    2001 Tacoma TRD Doublecab
    The URD 02 simulator should work if you take out the cat. Call URD, gadget should be able to help you
  4. Oct 29, 2012 at 3:59 AM

    kloc Member

    Apr 15, 2010
    First Name:
    00' tacoma ext.cab 4x4 2.7
    3" Toytec Lift w/ 2.5" Pro Comp aal's, K&N 57 Series FIPK cai, MagnaFlow Cat-back Dual Exhaust, Delta Low Profile Polished Aluminum Diamond Plate Toolbox, Alpine CD Deck w/Ipod Interface
    I had the same problem with mine last year. fuel injector went bad, over fueled and melted the front cat. The end result was removing the guts with a steel concrete stake and then purchased the URD o2 simulator. CEL was on and off for a couple weeks and then no problems since then. truck sounds much better without the front cat and seems to have just a touch more mid-top power... it pulls my 17 foot fiberglass bassboat a bit better anyway :)

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