bad vibes?

[stolibears]

seems that when I start moving in 1st at about 2000rpms the engine does just a little bit of work I get a really low loud vibration for just a second, comming either from the header or the cat (at least that is where is sounds like it is comming from). I think it only happens on a cold startup also. If the engine gets warmed up and I startup in traffic, no bad vibes.

I've double checked to make sure there is no exhaust leaks, and that all bolts are tight.

should i be concerened? is there a fix?

I just installed the DC sports header.

Injen CAI
DC sports 421 header
Powercore Hi-Flow Cat
Apexi WS exhaust

 

[kellog]

this happends on my brothers accord alot, his ruber hangers are close to shot and doesnt want to replace, so the exhaust will slip out of the hanger on one side and mike a loud vibrate noise. might wanna crawl under your car and check out the exhaust and make thing is all bolted tight...agian.

 

[baby99si]

It is most likely from your cat area did you put a collector on with the header?

 

[banzai]

did you forget to install the donut looking gasket at the end of the header? This might be the problem...

 

[stolibears]

I'll check the bolts on the cat back, this I haven't checked yet.

Donut is on the new header, but I did notice that the spring bolts I re-used that connect the cat to the header are as tight as they can be and it may not be tight enough(if that makes sense). The bolts only have threads on maybe the first inch of the bolt so you can only tighten it so far.

baby99si It is most likely from your cat area did you put a collector on with the header?

umm don't know about the collector. I just assumed it was built into the header. What am i looking for?

Theory: I'm am sure now that the sound disappears when the engine is warm. i'm thinking it may be the space inbetween the header and the car, and the donut has something to do with it. Something in the mix expands when heated, thus closing that gap that makes the vibes go away. When these peices are cold the gap is there, and the flow is slow so the exahaust gases find their way out at the connection of the header and the cat, thus making the noise.

I'm not going to find out for a while. It is nasty rainy here in C'ville till tomorrow. I'll have to check later in the week. Thanks for the suggestions though.

 

[T!mmy]

If I'm right...it's in your cat. My car does the same thing. Really annoying, On my car the cat is uhh breaking up I suppose on the inside so I guess I'm about to go with a high-flow cat or something.