how to bypass o2 on the cat 2001r/t

I gutted the cat out and now my check engine light is on. WHAT DO I DO

What is the point, the Cat on the R/T doesn't take away hardly any HP anyway?
Replace it with a Catco Low Restriction Cat.
Unless you are using the Car for racing, off road use only, it is illegal for you to gut your CAT, if someone assists you in defeating the OBDII system, they would be an accessory to your Federal crime.

It's for racing. We don't have those laws in AL. Thank you

It's for racing. We don't have those laws in AL. Thank youThen take the cat off. I don't know how to bypass the O2 sensor other than maybe going with an aftermarket PCM.

thanks!

If it is for racing on an unlicensed vehicle (BTW, Emissions is Federal and applies in all states), you can put a resister in place of the 2nd O2 sensor, you will have to find out what the resistance is of your O2 sensor is when it is happy and install a resister with that same value.

What is the point, the Cat on the R/T doesn't take away hardly any HP anyway?
Replace it with a Catco Low Restriction Cat.
Unless you are using the Car for racing, off road use only, it is illegal for you to gut your CAT, if someone assists you in defeating the OBDII system, they would be an accessory to your Federal crime.

are you a federal employee or something??? maybe a frustated cop? or a "peace-man" that never got over the '60s? let people make their own choices.
I'm plenty sure he knows about OBDII rules.

Found this on the .org


Removing the downstream oxygen sensor on a Neon

First, a little bit of background information so that you fully understand
what you are doing, and the potential consequences that could occur if the correct actions are not taken.

The most important thing to understand is what the downstream oxygen sensor is used for. Many people think that it is only used is to check for a
functional catalytic converter; and that is simply not true for most Neons.
For 1995 Neons, which was not OBD-II compliant, the downstream oxygen sensor is there to check for a functional catalytic converter, but since the 1995 Neons were not OBD-II compliant, it does not necessarily light the check engine light (more on this later). For 1996 to 1999 Neons, it not only checks for a functional catalytic converter, it also modifies the fuel ratio in an effort to reduce emissions. The downstream oxygen sensor will not vary the fuel ratio enough to significantly affect your fuel mileage.

Now, if you want to remove your downstream oxygen sensor, read below.

IF, AND ONLY IF YOU HAVE A 1995 NEON:
You have a few options, which I will explain below.
1.) Simply remove the downstream oxygen sensor, and let the connector
dangle. This will work for some 1995 Neons. Since the 1995 Neons were not OBD-II compliant, you may not get a check engine light. One of the
requirements of OBD-II was to light the check engine light if the computer
did not detect a functional catalytic converter. Because the 1995 Neons
were not OBD-II compliant, the computer may or may not feel the need to light the check engine light.
2.) If you have tried unplugging the downstream oxygen sensor, and got a check engine light, you can try the "resistor trick." This involves
soldering a ¼ watt, 1 megaohm resistor into the black wire of the
downstream oxygen sensor. This will effectively fool the computer into
thinking there is still a catalytic converter in place, by changing the
output of the downstream oxygen sensor. The resistor trick will only work
if you leave the downstream oxygen sensor in the exhaust piping. You cannot remove the downstream oxygen sensor from the exhaust piping, coil it up, and use the resistor trick; it does not work. I have personally (along with about six of my friends) have tried to use the resistor trick without the downstream oxygen sensor in the exhaust pipe, it does not work that way. The downstream oxygen sensor MUST be in the exhaust pipe for the resistor trick to work.
3.) For 1995, Mopar Performance PCMs will ignore the downstream oxygen sensor, so you can safely remove the sensor without the check engine light popping up. AFX does not manufacture a computer for the 1995 year Neon.

IF YOU HAVE A 1996-1999 NEON:
1.) Go to www.casperselectronics.com, and purchase a MIL eliminator. This clever little device plugs into the engine wiring harness, and modifies the oxygen sensor heating circuit, and converts it into a signal tricking the
computer into thinking the downstream oxygen sensor is still in place. A
MIL PLUG IS NOT JUST A RESISTOR! I cannot stress this point enough, many "uneducated" people think this is just a 39-cent resistor, and they are ripping people off. I personally have one of these, and have used it for almost 20k miles, and I have yet to receive one oxygen sensor related code.
2.) You can try the resistor trick. This involves soldering a ¼ watt, 1
megaohm resistor into the black wire of the downstream oxygen sensor. This will effectively fool the computer into thinking there is still a catalytic
converter in place, by changing the output of the downstream oxygen sensor. The resistor trick will only work if you leave the downstream oxygen sensor in the exhaust piping. You cannot remove the downstream oxygen sensor from the exhaust piping, coil it up, and use the resistor trick; it does not work. I have personally (along with about six of my friends) have tried to use the resistor trick without the downstream oxygen sensor in the exhaust pipe, it does not work that way. The downstream oxygen sensor MUST be in the exhaust pipe for the resistor trick to work.
3.) Purchase an AFX RACE PCM. For 1996-1999, AFX PCM will ignore the downstream oxygen sensor, and you can safely remove it without fear of the check engine light popping on. Yes, it is expensive. Yes, it works. 1996-1999 MOPAR PERFORMACE PCM DOES NOT IGNORE THE dOWNSTREAM OXYGEN SENSOR; YOU WILL GET A CHECK ENGINE LIGHT IF YOU REMOVE THE DOWNSTREAM OXYGEN SENSOR WITH A MOPAR PERFORMACE PCM.

IF YOU HAVE A SECOND GEN NEON
sllywhtboy wrote:
2000 PCMs were just-about the same as 96-99 so it should have the same effect as a 1st gen. 2001-2002 PCMs are different. 2003 PCM is different again (NGC). 2004 is supposed to be different even more. (next rev, NGC)

02ACR wrote:
I called Caspers a while back and the guy on the phone said that they make a sim that will work, but you have to hardwire it in because Mopar has propriatory rights to the *technology* used in the the plug, and there is no other source to get them from. Hardwiring is easy, but I have my doubts about it working..........and spending $50 to find out the sim doesn't work would kinda' suck. I'd just weld a bung in the piping right past the header.

Jackrabbit wrote:
My sensor worked for about a week (Casper, but I hear it's exactly the same as the Afx unit)... well I didn't throw any codes for a week at least. Than it proceded to kill my upstream sensor, running too rich I'd wager. BTW my car is a 2K1 with 2K2 magnum motor and PCM in case that matters. My advice is to just run a downstream sensor. Weld in a bung if you have to, lengthen the wires, whatever. The sims are not woth the headache in 2nd gens. You will spend more money in the long run trouble shooting and replace sensors. www.oxygensensors.com is your friend!


Chris Barnett wrote:
The Casper's 02 simulators DO NOT work on 2002-2003 neons. The AFX sims are the same as the Caspers, even made by the same designer. Get rid of it, it is a useless piece of crap as far as your car is concerned. It will continue to run like crap until you toss it. The AFX computer ignores the downstream sensor, the Mopar doesn't AFAIK. But the problem is with second gens, at least 2002+, for which no aftermarket PCM exists yet.

Greg Smith wrote:
I don't have any personal experience with theDownstream O2 simulator, but I am quite familiar with how the SBEC III PCM's fuel control works. Additionally, I consulted with Jackrabbit when he was having his O2 sensor related problems. I suspect that the problem with the sim is that on the Chrysler SBEC III PCM, the downstream O2 sensor has some influence on fuel control in addition to its role for the cat monitor. On other brand vehicles, the only purpose of the downstream O2 sensor is to monitor catalyst efficiency. The puzzler for me is why the sim apparently works OK on 1996-99 neons -- the downstream O2 sensor has an effect on fuel control on those cars too.



FINALLY,
I do not recommend removing the downstream oxygen sensor without using a method to eliminate the check engine light. I have driven my car without the downstream oxygen sensor, with the check engine light lit, and the car ran lean.

I hope this has helped people make an informed decision on what route to take to remove their downstream oxygen sensor from their Neon. The ways I have listed will work, when followed properly. There are other ways to remove the downstream oxygen sensor, but they either have a small success rate, or they are not viable option.

Last edited by ErikJohnson on Thu May 29, 2003 3:11 pm; edited 1 time in total
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bemidjineon43
Neon Enthusiast


Joined: 23 Apr 2004
Location: minnesota
Posted: Fri May 28, 2004 10:18 am Post subject: Re: How To: Remove the Downstream Oxygen (O2) Sensor


1.) Go to www.casperselectronics.com, and purchase a MIL eliminator


www.casperselectronics.com
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future mods:
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Axles
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tcd04
Neon Enthusiast


Joined: 21 Feb 2004
Location: Midwest, Southern Minnesota
Posted: Fri Jun 04, 2004 11:59 pm Post subject:



Go to www.o2simulator.com buy one, wire it up, and forget about the downstream o2 sensor and the CAT with this baby. Although, this is for 1st Gens, the 2nd Gen guys are still out in the cold.
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All outgoing/incoming mail scanned by Norton AntiVirus 2005. Don't you just love the punks writing viruses? Well, it puts money in my pocket anyway!

1995 Dodge Neon, 2.0 SOHC ATX, waiting for some upgrades, hehehehe....

Car: $1300
Parts: Never Done...
Driving Enjoyment: Priceless



enjoy.................

(BTW, Emissions is Federal and applies in all states)But not every city tests for emissions during the car inspection! Here in Houston, we test for it, but up in Huntsville, they don't.

Most places don't test for it, I'm in an area that doesn't test.
However, when you do a title transfer there is a form that you initial (that most people don't read) that warns you that altering emmision control equipment is a Federal offence. For what it is worth I guess...Most people ignore it....It makes your vehicle worth $0 resale if you are trying to sell it to someone who has to pass testing to register the vehicle in their name.

Actually, I am a Government employee.
I like the challenge of modding my vehicles in a legal manner. It is easy to get more power by cheating the system; following the rules... now that is hard. Good luck on your project. It does seems like it would have been easier to replace your CAT with a CATCO low restriction unit, kept your car legal and didn't have to deal with the CEL. IMO A $100 CatCO would have been cheaper than a $300 engine controller that ignore the sensor you are trying to bypass.

IMO A $100 CatCO would have been cheaper than a $300 engine controller that ignore the sensor you are trying to bypass.True, but the PCM will add HP too! Not just get rid of the cell, again I don't know this for sure though.