What's the purpose of this pipe?

[civic_mods]

It just seems like sucking hot air from the header????
i try to remove the other end of the header side,
but once i removed it,the exhaust got black smoke coming out(running rich?)
i attacth it again,then the black smoke gone.........why:confused:
that pipe is sthing to do with idle,air/fuel ratio for carby??????

becos i want to remove that pipe and block it off for cold air

and if i change to aftermarket extractor,i can't keep that cover....
the newer model D/B series engine doesn't seems to have that pipe from the extractor cover....
this make me concern....

any help would be great!!!
thanks

p.s pictures credit and taken by forum member Petronas

http://i4.photobucket.com/albums/y136/ch_cky/img0031cz6.jpg

[muhhan]

I'm not 100% sure on this but my guess is that if black smoke is coming from the exhaust when this hose is removed it would indicate that not everything is being burned. Perhaps the exhaust is actually sucking fresh air from the intake (venturi effect) and the fresh air helps the exhaust fumes to fully oxidise or the catalytic converter to do its thing.

[Eclipsor]

I'm fairly sure it is part of the choke mechanism. You'll notice just above it on the cold air intake is a valve that opens and closes. It opens when you first start up so that you are getting hot air to help everything to warm up

[ECU-MAN]

as above

its an old skool emmisions thing

[civic_mods]

so for carby,i can't change those stainless CAI or aftermarket extractor either???

[Eclipsor]

Why would you need to convert it to a mechanical choke? Choke is controlled by coolant tempurature isn't it? Just block off the vac tube going to the hot air bypass. If you wanted to change to extractors I reackon just get rid of the hose. You should be able to muck around blocking things off etc to see how badly your cold start would be effected.

[Rasputin]

My brother's swift had the same hose disconnected, I noticed when I was giving the bay a look over. His mechanic hadn't even noticed.
It also has a hole in it, so I'll tell you if I see any difference when I replace the pipe in a day or two. But all I can say is, it's been running without noticeable issue without it being disconnected.
Keep in mind that this is a car he's just bought, and so has not had it through cold winter starts etc.

[civic_mods]

so should i just keep that hose for cold start
or
take it off for more Cold air?

[yourfather]

... if its stock, leave it stock.

[Rasputin]

It sounds like it's supposed to 'kick in' with exhaust heat when it's meant to.

I don't think putting cold air into a system based on benefiting from hot air would be a wise thing. But, that being said, will have to see if there's a difference when i repair my brother's pipe. I agree with yourfather.

[Eclipsor]

If by take it off for more cold air you mean for performance increase purposes then I wouldn't bother. Just leave it to do it's job.

[civic_mods]

haha....thanks for all the help

i reckon i will just leave it there.......

my car is slow anyway....lol....won't benefit much by remove the hot air pipe.......

[CRXTC-4]

yeap have a fun time starting the thing without it :P