cat back exaust

if you have an exaust sensor what will happen if I put a strait pipe in? is it ok?

Reply to
Losen5004
Loading thread data ...

you'll throw engine codes, I'd suggest not removing the catalytic converter, since its pretty much already a straight through design, but if you must, you'll have to get an o2 sensor simulator.

Reply to
Paradox

could i put a performance cat. on it instead

Reply to
Losen5004

Yes, but depending on the how much you modify the exhaust it's probable the car will need to learn new fuel/air curves. However, contrary to what the previous poster suggested you DO NOT want to completely remove the catalytic converter if you plan to license the car for street use.

  1. The engine is designed to run with a certain amount of back pressure. Removing the cat reduces this back pressure and I've seen it where some idiot removed the cat and then complained the car ran like sh*t and kept backfiring.
  2. Removing the catalytic converter is against the law as is removing any piece of OEM smog control devices. A reputable shop will not give the car a passing inspection if the cat has been removed.
  3. A well designed exhaust system can accomedate (sp?) the catalytic converter and still give you both the performance and 'exhaust note' you desire.
Reply to
null

Reply to
null

Yeah he really SHOULDN'T take the cat off, backpressure doesn't really play that much into it, its more of a "don't pollute" factor. I wish he had said what kinda car he has, then exhaust options are a little easier to nail down.

Most of the newer cars have a good honeycomb designed catalyst, I was gonna put a magnaflow high flow cat on my monte, but after checking more into the stock exhaust, Its not really needed. However on all the new W-body cars, it seems some engineering genius decided that putting in a really tight U-bend would be an excellent thing to put in the exhaust, as to give the O2 sensor a nice shielded place to sit. I've been meaning to cut it out and put in a straight section there with an O2 sensor bung, but have been pretty damn lazy lately to finish that little project. Besides the exhaust manifold, thats really the only bad part of the design, and the manifold is excusable at least since GM engineers arn't going to develop tuned headers for every vehicle they make.

From what I've been able to understand, backpressure becomes a problem when the exhaust is so open, that the flow velocity of the gasses slows down to where its getting in its own way, like putting a 3" pipe on a geo metro, there isn't enough flow there to justify it, so that it slow down in the pipe and ends up not flowing easily, thus suctioning the next exhaust charge out of the last firing cylinder. If you keep it in its sweet spot tightness zone, then

Reply to
Paradox

with an aftermarket exhaust, you will get a service engine light for the O2. Mine took about 6 months. I installed the O2 simulator to take care of it. What car are you talking about anyway?

Reply to
Nascar24Rulz

What pray-tell is an O2 simulator ??

Rich...

Reply to
Guess

the simulator sends a "factory" signal back to the pcm to prevent the service engine soon light from coming on. it is necessary bc the higher flow exhaust sets the light in turn making your engine run really rich which burns gas

Reply to
Nascar24Rulz

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.