Engine Sounds Like 2-Stroke

GaryC

Well-Known Member
Joined
Sep 21, 2006
Messages
4,001
Location
Adelaide
Car(s)
'90 Miata, '12 Octavia RS
I've got this problem recently where the car exhaust sounds like an old fishing boat's 2-stroke engine. It only has the sound when I'm accelerating; lift off and constant speed doesn't have the sound.

Here's a video from about 1 week ago, I've sinced replaced the headers as I thought they were cracked, but that didn't fix it. I'm thinking it's the cat converter, but I'm hoping you guys can correct me if I'm wrong!

 
I'm thinking that's an exhaust leak. Do you have an oil leak somewhere? It looks like you're burning oil.
 
Sounds like an exhaust leak to me too. If you just replaced the headers, check to see if it's leaking at the manifold/head, because chances are it didn't seal properly.
 
it sounds like he replaced the headers because he thought they were the problem, which didn't go away when he replaced them.
 
I asked the problem on the Miata.net forum and it was pointed to the header or the cat. I just replaced the cat last year with a MagnaFlow Hi-Flow one, so I thought it probably wouldn't be the cat. (Though maybe that's why it is the cat...)

I've been wanting to replace the headers anyway, so I just moved that plan ahead. The smoke you see on the old headers was just yucky grease that was on my gloves from handling the headers. I don't have any oil leaks and I've used exhaust cement on the joint between the headers and the cat.
 
Take a section of hose (garden hose or otherwise) and listen through it at different locations along the exhaust system. Pay special attention to any bolted connections. This an easy way to really determine where the noise is coming from.
 
What do I particularly listen for?
 
It will sound like air escaping through the exhaust, kind of like the sound a steam engine makes, only much faster (chuh-chuh-chuh). There will be a very noticeable difference in noise between the leaking area and the non-leaking areas.
 
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