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Old 04-20-2013, 10:05 PM   #1
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Default NA Post Turbo install vacuum leak

Hello guys,

I THINK I might still be suffering from an air leak or something causing my car to run lean idling.

The car is a 92 NA 1.6L, pieced together turbo with intercooler, AEM UEGO air fuel meter, RX7 460CC injectors, Megasquirt PnP.

I had a vacuum leak I found which was a nipple under the throttle body hidden behind a bracket which I think goes straight to the intake manifold.

I seems like all intake manifold side leaks are plugged, I can't hear or see any, yet my AFR at idle is still high with injector specific required fuel settings (18-20:1).

So now I am turning my attention to the valve cover breather, I have the PCV on one side and slapped a basic small air filter on the exhaust side breather, will this be the source of an air leak? My turbo kit doesn't have anywhere I can route the valve cover breather back into via a tube :(.

I'm just trying to found the source of my high AFR, my idle is some what smooth, I hover right around 900-950rpm which I think is an acceptable fluctuation, I haven't driven the car in a while so I don't remember.

BTW I haven't put the car on the street yet, I was trying to straighten out this idle issue and make sure I am 100% fluid leaks free.
Thanks for reading, and any help.
f575gtc is offline   Reply With Quote
Old 04-20-2013, 10:44 PM   #2
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What would make you believe it's vacuum related and not the tune that is the problem. Idle is one of the trickier things to tune out for the first time.
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Old 04-20-2013, 10:54 PM   #3
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it might not be a vacuum leak at all, but I want to make sure I cover all my bases.

There was a vacuum leak I over looked which I fixed, but I am curious is the breather on the valve cover can cause a vacuum leak on the 1.6.
If it can't then I know I have all my leaks squared away and I will start playing with the fuel tables and adding more fuel around the idle kpa.

I think I can still hear a leak because I hear a faint hissing noise, but I dunno if it's from the spinning belts, or something else.
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Old 04-24-2013, 11:48 PM   #4
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having the valve cover breather open like that will not cause a vacuum leak. do you have a boost vac gauge? i pull 20inmg at idle
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Old 05-01-2013, 03:57 PM   #5
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did you do any tuning when there was a leak?
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Old 05-01-2013, 05:39 PM   #6
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I did, but once I noticed I did have an air leak, I stopped tuning, fixed all air leaks, and reloaded the base map again to start from square one.


I don't have anymore air leaks now, am pulling about 18 psi in vacuum (I think my gauge reads vacuum in psi as well).

and I started retuning with no leaks.
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