Will very low exhaust BP cause a CEL

jimsiggy · March 19, 2006

2001 5.3 Z71 I had the muff shop replace my muffler with a straight piece of pipe. They installed a pipe with a smaller than stock diamater. I asked them why and they said I would get a check engine light if there were not some BP. He said the install slightly smaller pipe than stock so this won't happen. I think the guy just grabbed the wrong size of pipe and just made it fit. It sounds good and is not too loud at all, but i did this as a poor mans cat back system, and I'm looking for a better flowing system. They said they would replace it with larger pipe, but that it would cause the trouble code. Is this just BS?

ZZebes · March 19, 2006

It is true that these vortec engines NEED Back pressure for any kind of low end torque but it depends what you want

Mr. Smith · March 19, 2006

2001 5.3 Z71 I had the muff shop replace my muffler with a straight piece of pipe. They installed a pipe with a smaller than stock diamater. I asked them why and they said I would get a check engine light if there were not some BP. He said the install slightly smaller pipe than stock so this won't happen. I think the guy just grabbed the wrong size of pipe and just made it fit. It sounds good and is not too loud at all, but i did this as a poor mans cat back system, and I'm looking for a better flowing system. They said they would replace it with larger pipe, but that it would cause the trouble code. Is this just BS?

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Why would you put a straight pipe on and remove the muffler? That is stupid as hell and does nothing more than case folks to get their elected officials to enact stupid ass sound abatement rules.

2004GMC1500CC · March 19, 2006

2001 5.3 Z71 I had the muff shop replace my muffler with a straight piece of pipe. They installed a pipe with a smaller than stock diamater. I asked them why and they said I would get a check engine light if there were not some BP. He said the install slightly smaller pipe than stock so this won't happen. I think the guy just grabbed the wrong size of pipe and just made it fit. It sounds good and is not too loud at all, but i did this as a poor mans cat back system, and I'm looking for a better flowing system. They said they would replace it with larger pipe, but that it would cause the trouble code. Is this just BS?

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Will it pass inspections without a muffler?

jimsiggy · March 19, 2006

2001 5.3 Z71 I had the muff shop replace my muffler with a straight piece of pipe. They installed a pipe with a smaller than stock diamater. I asked them why and they said I would get a check engine light if there were not some BP. He said the install slightly smaller pipe than stock so this won't happen. I think the guy just grabbed the wrong size of pipe and just made it fit. It sounds good and is not too loud at all, but i did this as a poor mans cat back system, and I'm looking for a better flowing system. They said they would replace it with larger pipe, but that it would cause the trouble code. Is this just BS?

<{POST_SNAPBACK}>

Why would you put a straight pipe on and remove the muffler? That is stupid as hell and does nothing more than case folks to get their elected officials to enact stupid ass sound abatement rules.

<{POST_SNAPBACK}>

I beg to differ, my truck is not obnoxious at all. In fact it is no louder than some of my buddy’s trucks and cars with high dollar cat-backs. You see I’m no kid and this aint my first rodeo. This is a trick I learned several years ago from a ford dealership. They were cutting the stock mufflers off new trucks and replacing them with pipe. Since the cats were still in place, sound was mild, but noticeable, and gleaned a few more MPG. With the Cats in place and 10-12 feet or so of exhaust pipe the sound is mellow; unnoticeable at idle and has a nice growl on the road (nothing like open headers!). I have no inspection to deal with where I live. What I think is "stupid as hell" someone giving a negative opinion without any real knowledge on this subject. Mr. Smith have you ever heard my truck? Look I am with you about stupid laws and I don't want a loud vehicle, and don't have a loud vehicle. I have modified many cars and trucks and motorcycles in my time, and you don't always have to spend big bucks on after-market parts to gain performance. I simply do not have the OBD-II knowledge, with regard to my question, so I choose this forum to ask.

Siggy

Butch 02 Denali · March 19, 2006

If the cats are left in place Siggy, I have never seen any cat-back exhaust with any size pipe set a code, even with no muffler. Look at the Magnaflow mufflers, absolutly straight thru with no restriction and 0 backpressure. Never seen one of those set a code!

jimsiggy · March 20, 2006

If the cats are left in place Siggy, I have never seen any cat-back exhaust with any size pipe set a code, even with no muffler. Look at the Magnaflow mufflers, absolutly straight thru with no restriction and 0 backpressure. Never seen one of those set a code!

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Butch, thanks for answering my question.

Siggy

Mr. Smith · March 20, 2006

2001 5.3 Z71 I had the muff shop replace my muffler with a straight piece of pipe. They installed a pipe with a smaller than stock diamater. I asked them why and they said I would get a check engine light if there were not some BP. He said the install slightly smaller pipe than stock so this won't happen. I think the guy just grabbed the wrong size of pipe and just made it fit. It sounds good and is not too loud at all, but i did this as a poor mans cat back system, and I'm looking for a better flowing system. They said they would replace it with larger pipe, but that it would cause the trouble code. Is this just BS?

<{POST_SNAPBACK}>

Why would you put a straight pipe on and remove the muffler? That is stupid as hell and does nothing more than case folks to get their elected officials to enact stupid ass sound abatement rules.

<{POST_SNAPBACK}>

I beg to differ, my truck is not obnoxious at all. In fact it is no louder than some of my buddy’s trucks and cars with high dollar cat-backs. You see I’m no kid and this aint my first rodeo. This is a trick I learned several years ago from a ford dealership. They were cutting the stock mufflers off new trucks and replacing them with pipe. Since the cats were still in place, sound was mild, but noticeable, and gleaned a few more MPG. With the Cats in place and 10-12 feet or so of exhaust pipe the sound is mellow; unnoticeable at idle and has a nice growl on the road (nothing like open headers!). I have no inspection to deal with where I live. What I think is "stupid as hell" someone giving a negative opinion without any real knowledge on this subject. Mr. Smith have you ever heard my truck? Look I am with you about stupid laws and I don't want a loud vehicle, and don't have a loud vehicle. I have modified many cars and trucks and motorcycles in my time, and you don't always have to spend big bucks on after-market parts to gain performance. I simply do not have the OBD-II knowledge, with regard to my question, so I choose this forum to ask.

Siggy

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O..K I can react in the manner of MY choosing as I see alot of truck owners rig crap up and I have no choice at a stoplight but put up with it. Call it what you like but I don't have to condone it period. This is a rig job plain and simple.

Have a nice day.

jimsiggy · March 20, 2006

O..K I can react in the manner of MY choosing as I see alot of truck owners rig crap up and I have no choice at a stoplight but put up with it. Call it what you like but I don't have to condone it period. This is a rig job plain and simple.

Have a nice day.

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Feel free to express your opinion. I do and I choose to use tact when doing so. I don’t expect others to necessarily agree to it, so they shouldn’t expect me to agree with theirs. In the end, whether it’s a “rig job” or a cheap trick; whether you “condone” or disagree, I see it as doing now, what I can, with what I have.

Siggy