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Changed intake manifold gasket on my 03 Tahoe 5.3 z71 one…

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Changed intake manifold gasket on...
Changed intake manifold gasket on my 03 Tahoe 5.3 z71 one day while changing both knock sensors. Put everything back together and when driving feels like loss of engine power getting past 20 mph heard a whistling noise sounds like it's coming from the top center of the intake or possibly on the back where the booster nipple is. When i take the pcv valve out of grommet and put finger over the hole the noise stops Changed out the PCV valve hose and grommet that go into the valve cover, also changed Old 45 that went from the fuel pressure regulator to the intake manifold, changed out purge canister valve hose. Cleaned mas. Ran homemade smoke test and really couldn't see much maybe a wisp of smoke coming from booster nipple. Any ideas or suggestions for something to help fix the problem? Would the o rings on the fuel lines that hook onto the fuel rail cause a vacuum leak
Submitted: 1 month ago.Category: Chevy
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Customer reply replied 1 month ago
Also changed fuel filter bought an ODB code reader and was getting 171 and 174 but reset check engine light and haven't gotten any codes in about 100 miles
Answered in 59 minutes by:
1/7/2018
Chevy Mechanic: Chris (aka-Moose), Technician replied 1 month ago
Chris (aka-Moose)
Chris (aka-Moose), Technician
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Over this course of 100 miles, how many times has it cooled and been restarted and driven?

Do you have a scan tool that can monitor fuel trims?

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Customer reply replied 1 month ago
Drove it about 4 times to the store so cooled down about 8 times and started 8 times. No I do not have a scan tool that can monitor fuel trims should I get one sure would help right
Customer reply replied 1 month ago
I know I have a vacuum leak and engine is running too lean just can't find the vacuum leak why would the noise stop when I pull the PCV valve out of The Grommet and put my finger Over the Hole and take my finger off the hole the noise reappears
Chevy Mechanic: Chris (aka-Moose), Technician replied 1 month ago

Yes, a scan tool would help.

Have you tried the flammable spray like brake cleaner to find the leak?

When you unplug the PCV is the intake side of PCV side the one making the noise?

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Customer reply replied 1 month ago
Yea I've tried the cleaner no change in rpms at all. When I pull the PCV valve/hose out of The Grommet on the valve cover I put my finger Over the Hole on the bottom of the PCV valve and the noise goes away when I release my finger off the hole I hear the noise on the top center of the intake and at the bottom of the PCV valve
Chevy Mechanic: Chris (aka-Moose), Technician replied 1 month ago

While running, and the PCV removed, is there air blowing out of the valve cover where the PCV was or is there a vacuum?

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Customer reply replied 1 month ago
Blowing out i believe
Customer reply replied 1 month ago
I'd have to check again
Chevy Mechanic: Chris (aka-Moose), Technician replied 1 month ago

Can you do that now or tomorrow?

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Customer reply replied 1 month ago
Tomorrow morning should it blowing out or vacuum and why
Chevy Mechanic: Chris (aka-Moose), Technician replied 1 month ago

It should blow out but very little. I am wanting to make sure there is not a vacuum from the breather on the other valve cover not hooked up wrong.

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Customer reply replied 1 month ago
Ok when I was looking at it earlier today it was cold outside and there was a little steam and smoke billowing out of the gromet when I took the PCV valve out of it
Chevy Mechanic: Chris (aka-Moose), Technician replied 1 month ago

At this time we need a tool that can do more than just reading codes. We need to monitor sensors and computer inputs.

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Customer reply replied 1 month ago
Ok have any idea or to many possibilities
Chevy Mechanic: Chris (aka-Moose), Technician replied 1 month ago

As of right now, I could only guess, which is not really any form of a valuable answer. We need a way to diagnose.

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Customer reply replied 1 month ago
When I get off work I can go get what I need to figure it out
Chevy Mechanic: Chris (aka-Moose), Technician replied 1 month ago

That will be great

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Chevy Mechanic: Chris (aka-Moose), Technician replied 1 month ago

Hello, Chris here again,

I am checking in to make sure you got everything you expected from my answer. The option to rate my response or reply is still available. I want to make sure you were pleased with what you paid for.

Thanks Chris

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