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Old 02-06-2009   #1
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Breather pipe help

Hi Guys,

I've traced a fuelling issue down to the small breather pipe going into the throttle body, if I blank both connections the car idles normally. If I fit the pipe it doesn't and the pipe isn't perished or split. Is there suppose to be a restrictor or one way valve in this pipe as mmine has nothing in it and i'm sure it wont vent from the throttle body to the larger breather all of the time.

Thanks from Ross
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Old 02-06-2009   #2
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Re: Breather pipe help

there is meant to be a little bit of coiled wire to act as a flame trap, but that is it.

blocking this pipe is curing the symptons but not the problem, there must be another leak somewhere - and blocking this just happens to lower the airflow enough to get it to idle correctly.

did you try blocking the ICV with your thumb to see if it stalls?

is the inlet manifold loose at all?
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Old 03-06-2009   #3
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Re: Breather pipe help

When you say block the ICV do you mean with the ICV removed from the TB as I cant see how to block it with it on the TB. Do you suspect the ICV to be broke or the seal to be leaking in outside air?
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Old 03-06-2009   #4
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Re: Breather pipe help

WHen I took the ICV off to clean it I put sealant around the seal so I doubt it leaking in air. Before I blanked off the breather hose you could see the injector going at full chatt, as soon as I blocked that pipe the flow slowed right down.
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Old 03-06-2009   #5
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Re: Breather pipe help

injector sertainly shouldnt be going at full chat at idle.
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Old 03-06-2009   #6
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Re: Breather pipe help

Ok i've cracked this one now, ARC's reply really got me thinking what the hell could be wrong and why blocking the connection the breather went to solved the problem. So I began to trawl through the history and just before things like lambda's started to be fitted the throttle body was changed. Turns out the two vacuum hoses on the back of the TB were the wrong way round. The hose from the breather was on the top connection, the hose from the EVAP was on the lower connection. Swapped them round and hey presto smooth idle at 900rpm. Can't test on the road right now as i've had a drink but i'll let you know if there is any difference.

Cheers from Ross
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Old 03-06-2009   #7
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Re: Breather pipe help

Quote Originally Posted by Boostjunky View Post
Turns out the two vacuum hoses on the back of the TB were the wrong way round. The hose from the breather was on the top connection, the hose from the EVAP was on the lower connection.
aye, that'll do it!

what i meant re blocking the ICV inlet, that was purely to eliminate a faulty ICV. If the ICV wasn't work properly, and allowing the car to idle at 1300rpm - blocking it would stall the engine. If it did not stall then it would've been a fair assumpetion that it was working fine, and that there is an air leak elsewhere.

i dont have a photo showing the top half of the TB with injector etc on it, but if you look at this photo, the bit circled in yellow is the air channel for the ICV and is that that i was suggesting you block off to test.
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