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question about intake manifold vacuum leak

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Old 03-12-2009, 10:01 PM
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Default question about intake manifold vacuum leak

I noticed today that my intake has a slight vacuum leak by the 4 and 6 cylinders, when I spray carb cleaner between the head and intake manifold the rpm rises slightly. Hasn't thrown any codes, doesn't miss, I found it by accident when I was spraying carb cleaner to remove some oil.

Should I worry about it?
Old 03-12-2009, 10:08 PM
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I actually just fixed a vacuum leak a few days ago. I hooked up my scanner and the LTFTs were maxing out. I check the TB and everything past the MAF first and all was good. So I pulled the intake and replaced gaskets. Its not good to have leaks, theyll make it do funky things. It was pretty easy to do, took a couple hours. Also it gives you a chance to clean the intake out really good inside and out.
Old 03-12-2009, 10:17 PM
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What are LTFT's ? Did you have a miss? Or other issues?
Old 03-12-2009, 10:21 PM
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Long term fuel trims. His engine was compesating with as much fuel as it could to make up for the leaking air.

You need to fix it.
Old 03-12-2009, 10:25 PM
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Long term fuel trims.

Basically the o2 sensors are detecting a lean mixture from air that is entering the combustion chamber that is not going through the MAF first. So the PCM adds fuel to compensate(LTFT). It can compensate about 25% of what it should be by either adding or subtracting fuel.
It did develop a miss, thats why I hooked up the scanner to see what was up.




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