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ok I will start by saying, i am no expert nor do I pretend to be. I own a 2004 3.8 v6 I'm getting check engine code, my cat is bad. I want louder sound plus im on a budget. so I'm wanting to have my friend who works at a muffler shop cut off all 4 and straight pipe. how do i go about "retunin
g" so I will not have the code plus get maximum gain from this mod. should I get a chip or take it to a shop or what?? my main concern is the car not running well, not the hp, which I know will not be a dramatic difference. btw no emissions where i live


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Correct me if I'm wrong but, removing the cats would mess up your oxygen sensors. So yes you would need one. You can buy a Bama tune cheap, and you can turn of the O2 sensors.


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Thanks so bama tune does offer an option to retune your car with out cats and removes the code? Iv never done a tune and just want to make sure i dont mess anything up, im a worry wart

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Yes, american muscle is about the best place to get a can tune. To be 110% you can always go to their site and ask them. Also it makes a great first mod. Just make sure when their writing your tune to say I want my 02 sensors turned off. Note( make sure your state has no emission laws.) if they do have laws like the state of California you could get fined big time for breaking emission laws )


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Correct me if I'm wrong but, removing the cats would mess up your oxygen sensors. So yes you would need one. You can buy a Bama tune cheap, and you can turn of the O2 sensors.


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It doesn't mess up your O2 sensors, they just read that there's no cats there and throw a CEL for catalytic efficiency low
 

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ok I will start by saying, i am no expert nor do I pretend to be. I own a 2004 3.8 v6 I'm getting check engine code, my cat is bad. I want louder sound plus im on a budget. so I'm wanting to have my friend who works at a muffler shop cut off all 4 and straight pipe. how do i go about "retunin
g" so I will not have the code plus get maximum gain from this mod. should I get a chip or take it to a shop or what?? my main concern is the car not running well, not the hp, which I know will not be a dramatic difference. btw no emissions where i live


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Since joining this site, I have seen much discussion regarding cat deletes, tuning, etc. much of which the discussion is based upon false PR advertising/promoted documents. So this is what you need to know.....

The OBDII systems is an extremely advanced, highly effective engine management system that can be slightly modified to give you a little more of what you may want....the OEM's set thing for "middle of the road so to speak"... whereas an individual may want more power or mpg....which is where most all of the new vehicles have a "selector switch" to choose what ya like! Now let's talk about cat deletes and defeating the downstream O2 sensors on your type of vehicle..... unless you change out the ecm to an aftermarket system you are looking for "trouble" in many ways.....

Now let me talk just for a minute of the issue of defeating the downstream O2 sensors- is just, not smart! Let me explain to you...

Production calibrations have an “inferred catalyst temperature protection model” which constantly calculates the temperature in the hottest part of the hottest catalyst. This calculated temperature is based on many PCM parameters, such as engine speed, load, ingested air mass, time, inlet air temperature, EGR flow rate and many others. When the catalyst model calculates that the catalyst temperature is about to exceed a level that is safe for the catalyst (generally around 1650 deg F), the PCM will richen the A/F mixture as necessary to lower the exhaust gas temperature and cool the catalyst. This richened A/F ratio will decrease power output, but is absolutely necessary to keep the catalyst from being permanently damaged and without the downstream sensors, the PCM can easily, consistently and once too many times over or under richen the A/F mix...making what a software engineer would call, "An erroneous conclusion"...

Now for those who are sooo smart to think that they can drop the cats & downstream O2 sensors and they are "fine"...this is equally NOT SMART. Ya see, there is also a "model" (please excuse the common terminology) for oxygen sensor protection and exhaust valve protection that when not taken into account can and will cause internal damage to the exhaust valves and because of the "wild" air/fuel mixture swings, this can induce cylinder washing because of the excess fuel. With regards to the valves, it is called "Tuliping" and happens over time resulting in catastrophic engine damage that any machinist can explain or show this to you and can even damage the remaining O2 sensors....and yes, this does pull HP away from the engine only for component safeguarding.

None of this happens immediately.......

Hope this helps................
 
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Beechkid
Can I use o2 spacers for cat delete?
IMHO, you're going to have problems because you are going to be getting voltage readings from the upstream location that are showing correct readings and the downstream sensor will be showing the same or very close to it instead of what it would suppose to show... i.e. the ecm is going to think that something is wrong with the fuel mixture and try to adjust to fix it....... just a very bad idea.
 
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