Wolf Warrior

I'm planning on putting on a set of pace setter LT's, with the y pipe. I want to chop off my cats (they're pretty much clogged). Does that mean I want to order the headers without the A.I.R. and EGR? Will I have any problems doing this (other than upsetting "atmosphere friendly" people)?

Buttercup

You could keep AIR and EGR with or without the cats, or get rid of them. Keeping the AIR system would be kind of stupid without cats because its primary purpose is to light the cats off quicker.

If you get rid of the cats, AIR, and EGR you will have to make the necessary changes to the PCM programming.

Other than it being illegal, louder, dirtier, and smellier this won't cause any problems... unless you've got (or will have) emissions testing.

TUFF LT1

Don't forget that you'll need O2 sims if you do anything to your cats...for off road use.

Buttercup

Nah, if you're removing the EGR and AIR systems than you need to reprogram the PCM. The catalyst monitors can be disabled as well. If you're not touching the PCM, then yeah you need some sims.

Wolf Warrior

Buttercup, louder is the idea . And I would rather not send the PCM away (its my daily driver, and don't wanna live without a car).

Both of you, what are o2 sims, what are they for, and how to you install them? (Im guessing they're exactly what they say, it simulates an o2 sensor rather than actually having one?)

Buttercup

Maybe at the ripe old age of 26 I can't stand loud Of course, I didn't have much room or money for anything more than the bullet mufflers on my exhaust.

Your PCM does a function test of both the EGR and AIR systems. If you remove them the PCM will eventually notice and light up that wonderful SES light on the dash. Unless of course you reprogram it.

Sims can be used to run "offroad pipes" in place of the cats. The PCM normally monitors the O2 sensors after the catalysts to determine their efficiency. If you remove the cats, the PCM sees it as malfunctioning catalysts. "Sims" duplicate a "clean" signal for the rear O2 sensors. Replacing the rear O2 sensors with these sims allows you to remove the cats without the PCM knowing it.

TUFF LT1

Like he said, if you can reprogram your PCM using Autotap or something ( I have a 95 so I use Tunercat, don't know what's best for you ) that would probably be the best bet. If you don't want to deal with that for whatever reason use the O2 sims.

Wolf Warrior

Right. Where can I buy these (u only need one?)? And how do you actually install them? Do you replace the o2 sensor, or do you put them somewhere else?

Buttercup

All kinds of places sell them for "offroad use", I would check with the supporting vendors

They replace the rear O2 sensors. Your car has four O2 sensors, one in front and one behind each cat. The front sensor is used by the PCM for closed loop fueling. The rear O2 sensor is only used to determine catalyst efficiency. If you wanted to run !cat you would buy two sims, remove the rear O2 sensors, and plug the sims into the wiring harness where the rear O2 sensors were once connected.

Wolf Warrior

Ok. And if I don't do either (send the PCM away, or replace the o2 sensors), all thatll happen is the SES light will come on? The car won't run like crap?

Wolf Warrior

And also, it won't matter if i just put the front o2 sensors back on even without a cat?

2000GTP

You can buy the sims. at several of the online stores, Summit, Jegs, Thunderracing, Speed-Eng., ect. They will run about 80-90 bucks for the pair. They are easy to install as they simply plug into the harness that is supposed to plug into the rear 02 sensor.

2000GTP

If you chopped off the EGR, AIR, and have the rear 02s disabled without a tune or sims. then yes your SES light will illuminate but the car will still run normally.

2000GTP

You will need the front 02s with or without a cat. The presence of the cat has nothing to do with what the front 02s do. The rear 02 sensors are the ones responsible for monitoring the catalytic converters efficiency so naturally if you have no cats. then you will not need the rear 02s.

Wolf Warrior

Awesome. Thanks for all the help guys!