ok heres the run down. I parked my Civcic in the garage for about 2 months while the snow was coming down. When i parked the car it ran perfect, sounded perfect no problems at all. Every two weeks or so i'd go turn it on and let it run for awhile, still sounded normal, then acouple weeks ago i bought a new Megan 4-1 header and put it in. Now that i've took it out of the garage and drove it, it has a deep rumble like a damn Subaru WRX....Nothing on the motor was touched execpt the header. Why is it making this sound..It drove good for acouple blocks then it started to act like it was misfiring, and was lagging..then after a while it drove normal again but still sounds like a subi...
My swap is a bone stock B20B with B16 head. I drove it again today and it drives good and pulls hard like before but it still sounds weird, i doubt the header would make that much of a diff in sound, what could it be?? someone please help...

 

a header can make ur exhaust sound diffrent

 

is the gas thats in old could of got water in your tank causing it to misfire from the fuel bieng old gummed up and water. just a thought

 

Bump

 

thats what i thought about the weird misfire, but that subi rumble doesnt sound normal to me, it sounds pretty kool, but i don't want nothing to get messed up..

 

check header gasket for leaks and where the collector meets secondary pipe.

 

i will, i suspect that the bolts prolly got a little loose after i ran it for awhile..Ill go back and tighten them up later, because its raining right now. Thanks

 

Please keep us posted, as I'm having a similar problem with my car. I just bought it, it came with a shitty Ractive header on it, so I'm not sure if that's the culprit. I've checked distributor, changed plugs and wires, and a bunch of other stuff. I found my intake manifold gasket leaking, so I'm waiting for it to show up so I can swap it. Let me know if you figure it out, I'll drop something in here and let you know if I figure mine out.

 

sounds good dude, I'm not going to be able to work on my car for awhile Because im going back to college for the week, Ill get to the bottom of it next weekend when i have time to check it all out. Lemme know if u figure it out before i do..

 

k so was able to re-tighten the all the bolts, and it still has that rumble, no exhaust leak so now i suspect that the dizzy is going bad and might be causing the rumble. or else a bad injector. I've read on other forums that a misfire caused by bad dizzy, spark plug wire, or injector would make my car sound like a subi, only problem is i don't know how to check if a dizzy or injector is bad or going bad..could someone help me out??
the cars idle is fine, nothing outta the normal, spark plugs are all good.

 

check all the spark plug wires to make sure they're making a connection with the spark plug and that you have spark. also check all your spark plugs and check the gaps. same thing happened to my teg awhile back it was bogging like hell until i lookod at my car and one of my wires was off and one cylinder wasn't firing because of that.

just make sure everything is tight. if not, maybe check you're timing, it could have skipped a tooth.

 

i recently removed the New Megan 4-1 header and installed my old 4-2-1 too see what would happen. and it sounds perfect the way a civic should sound. So this tells me my dizzy is good, I have good spark, good injectors, and good compression. Because it drives great sounds good and pulls hard. So just today i re-installed the New Megan header using the old gaskets, cuz the new ones that came with my header were no good..And the car sounds like a Subi again WTF. i drove it and it feels good and strong, just really loud and rumbles alot.

Any ideas why? U guys think adding a Hi-flow Cat would help? or re-tune?
My current set up is the Megan 4-1 then pretty much straight pipe to a skunk2 tip..
any ideas or suggestions would help..Thanks in advance.

 

from the sound of it thats just how that header's gonna roll...

 

that's what im starting to think. but u think a good Cat would help tone it down? because i don't like the sound it makes

 

maybe. if its like coming from the exhaust and not just it rumbling inside of it.
a resonator may work also. if you just wanna cut out the loudness.

 

well my set up has a resonator but its a short one.

 

anyone else have any input..also i noticed that the CEL came on after about a half hour of driving. i shut the car off and started it back up and it went away. then about 10 mins later it came back on. again shut it off and it went away..The CEL never came on with the old Header..

 

Put the goddamned old header back on.

 

dude thats what i feel like doing so i dont have to bust my head to figure it out, but i dont want to cuz I like my new one and also i gave the old one to my bro so its not mine anymore..

 

Did you over flow your oil? Is there smoke coming out your exhaust? Most likely just a bad gasket or loose bolts. Lets not hope you didn't drown your motor with oil...

 

I didn't get to read your post about a shorter resonator. It could be leaking through that...

 

check the nuts where header meets head, then where header meets down pipe, then where down pipe meets cat. you'll fine the problem. usually, after market headers come loose a week or so after. thats probably why it sounds like a subby.

 

oil is fine, not overfilled. No smoke, and ive had the header for awhile and its old bolted up tight. what ima do is borrow my friends 4-1 header to see if if sounds the same as mine if so then its just the way it is, if it sounds diff then something wrong with my new header. i know that theres no other exhaust leak because with my old header everything sounds perfect ..
im also thinking that the springs on the bolts connected to the down pipe might be too big thus not letting the gasket seal when i tighten them..cuz the springs are compacted all the way when i tighten the bolts

ive been busy with skool and work so i dont get to many chances to work on it or check stuff out..as long as it drives good in not too worried i just dont want that damn subi rumble

 

Check your header for any cracks?

 

Does it sound anything like this?

http://www.youtube.com/watch?v=CD3LAk_ifaw

This is my car, I've checked plugs, wires, distributor, timing.

It is bouncing off the 2-step limiter in the vid when revved and the vid quality sucks because it was taken with my Blackberry, but my car came with some shitty looking Ractive header on it. I believe it's 4-1 as well. Maybe this is the culprit?

*EDIT*

I just hit youtube and searched for Civic 4-1 Header
Listen to the results!!!

http://www.youtube.com/watch?v=6ZdR6...eature=related

http://www.youtube.com/watch?v=yCotMPiHi-o

http://www.youtube.com/watch?v=AWWp91GzzaI

I am thinking that is what is going on with both of our cars! The fact that you switched your header to your old one and the exhaust didn't have this same effect almost confirms it for me.