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Old Jul 2, 2013 | 08:49 PM
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Default catch can issue

I have tried searching and have read various catch can threads but not seeing anything directly related to mine...i hooked up a norris catch can on my engine (ls1)and the hose from the front passenger side valve cover i put to the intake and not the throttle body like most of the diagrams..the one from the catch can with my pcv valve in it i put to the throttle body and not the intake like most diagrams...the issue im having is that i had the car tuned and it idles perfect on cold start but i was worried about the functioning of the catch can so i switched the hoses like all the diagrams and the car will start for a brief second and then surge and die..

anyone have any ideas if i should leave it like it is or what am i to do so i can get it to idle with the hoses in the correct locations like the diagrams?

I also have a breather where the oil cap is and my 2 rear ports on the valve covers are joined with a tee and come to the top of the catch can..

any ideas?
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Old Jul 3, 2013 | 07:11 AM
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So here is my assessment: youre doing it wrong, lol. I am no expert, but here is my understanding. The pcv system is designed to put the case under mild vacuum and trickle enough makeup air so that the vapors circulate and get sucked through the intake

In the OE system fresh air comes from the IAC valve to the front of the passenger VC. Oil vapor comes from the backs of the VCs and goes into your manifold. The way you have that works is *** backward + a breather. The reason it works is because the giant vacuum leak you introduce via the breather cap to the manifold can be accomodated by the IAC staying closed.

When you hook it up per the diagrams you no longer have a giant leak and the iac must now do its job...but it doesnt know how until it has time enough to learn. Fire it up with the throttle cracked open a bit. Then keep it alive with your foot for 30 seconds or so and you should be able to let it run on Iits own

All that said, the breather cap and TB to the front of the p side VC connection are redundant. Pick one and cap the other.

I think that should work for you if you dont have other problems.
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Old Jul 3, 2013 | 07:21 AM
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Originally Posted by therabidweasel
So here is my assessment: youre doing it wrong, lol. I am no expert, but here is my understanding. The pcv system is designed to put the case under mild vacuum and trickle enough makeup air so that the vapors circulate and get sucked through the intake

In the OE system fresh air comes from the IAC valve to the front of the passenger VC. Oil vapor comes from the backs of the VCs and goes into your manifold. The way you have that works is *** backward + a breather. The reason it works is because the giant vacuum leak you introduce via the breather cap to the manifold can be accomodated by the IAC staying closed.

When you hook it up per the diagrams you no longer have a giant leak and the iac must now do its job...but it doesnt know how until it has time enough to learn. Fire it up with the throttle cracked open a bit. Then keep it alive with your foot for 30 seconds or so and you should be able to let it run on Iits own

All that said, the breather cap and TB to the front of the p side VC connection are redundant. Pick one and cap the other.

I think that should work for you if you dont have other problems.
ok, i will remove the breather and hook the 2 lines up correct and try to keep it running...do you think i will need to retune the idle or will the iac relearn on its own? the car idles so nice now though lol... but thats no good if the PCV isnt working..
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Old Jul 3, 2013 | 09:05 AM
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IAC will relearn. . .it should only have problems for a minute or two, maybe 3-4 starts. If I'm right and you have no other issues it should be fine after that.
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