Underpowered Possible vacuum leak

Angelo217 · Aug 31, 2024

2006 Chevrolet Tahoe 230k miles 5.3
Feels really sluggish and slow compared to my other 06 Tahoe with the same motor, feels like it has 50 less horsepower.

I hear a hissing noise when I give it a slight rev and let off it’ll hiss like it’s releasing pressure like a vacuum leak. I had my brother rev it up how I do and check under the hood.

The hissing noise sounds like it’s coming directly from the alternator, not sure if there are vacuum lines underneath that area hidden or not.

But if y’all could give me some pointers on why it might be so underpowered or maybe another place to look thanks

Scottydoggs · Aug 31, 2024

with all them miles a clogged cat is a possibility.

at idle you can spray some carb cleaner, flammable brake cleaner or the likes at the vac lines intake gasket areas, if the idle jumps up when you spray something, you found the leak area.

normally with a large vac leak that you can hear, the idle would be all choppy and kinda sound like you just put a huge cam in it with a 500 rpm surge.

you can also take the belt off, fire it up and see if the sound is gone as well. could be the alt is locking up, water pump, or even the ac compressor clutch ring is worn and making the noise. check the idler pulleys too. make sure they spin freely and smoothly with very little side to side play.

Angelo217 · Aug 31, 2024

Scottydoggs said:
with all them miles a clogged cat is a possibility.

at idle you can spray some carb cleaner, flammable brake cleaner or the likes at the vac lines intake gasket areas, if the idle jumps up when you spray something, you found the leak area.

normally with a large vac leak that you can hear, the idle would be all choppy and kinda sound like you just put a huge cam in it with a 500 rpm surge.

you can also take the belt off, fire it up and see if the sound is gone as well. could be the alt is locking up, water pump, or even the ac compressor clutch ring is worn and making the noise. check the idler pulleys too. make sure they spin freely and smoothly with very little side to side play.

My other Tahoe had 70k more miles than mine, and she’s got the OG cats on it. I’ll try taking the belt off and using some carb cleaner when it cools down a little thanks!

Angelo217 · Aug 31, 2024

here’s the vid of the noise it’s making.

Doubeleive · Aug 31, 2024

Angelo217 said:
here’s the vid of the noise it’s making.

rig up a backpressure test and see what psi it has, just because it has more or less mileage than another does mean anything, mine has 170k and was clogged
you just need a gauge and a hose with a nozzle of some form attached to fit in the 02 sensor bung
you could probably just use a pipe fitting, hose, gauge, couple clamps.

https://www.napaonline.com/en/p/BK_7012005?cid=paidsearch_shopping_dcoe_google&campaign=GSC-Catch-All&campaign_id=6478877959&adgroup_id=79272987338&adtype=pla_with_promotion&gclid=Cj0KCQjw_sq2BhCUARIsAIVqmQtGqTcPWAvBVYr9qp9vXQG4prKjo1PHXrD9gDxuNPRjJluD57VTY9IaAj-nEALw_wcB&gclsrc=aw.ds&gad_source=1

Fless · Aug 31, 2024

That whine is not normal, and sounds like a pulley or tensioner issue with one of the belt paths. Power steering have enough fluid in it?

Angelo217 · Aug 31, 2024

Doubeleive said:
rig up a backpressure test and see what psi it has, just because it has more or less mileage than another does mean anything, mine has 170k and was clogged
you just need a gauge and a hose with a nozzle of some form attached to fit in the 02 sensor bung
you could probably just use a pipe fitting, hose, gauge, couple clamps.

https://www.napaonline.com/en/p/BK_7012005?cid=paidsearch_shopping_dcoe_google&campaign=GSC-Catch-All&campaign_id=6478877959&adgroup_id=79272987338&adtype=pla_with_promotion&gclid=Cj0KCQjw_sq2BhCUARIsAIVqmQtGqTcPWAvBVYr9qp9vXQG4prKjo1PHXrD9gDxuNPRjJluD57VTY9IaAj-nEALw_wcB&gclsrc=aw.ds&gad_source=1

Where would I hook that gauge up to and what would this tell me/ what psi reading should suggest normal range

Angelo217 · Aug 31, 2024

Fless said:
That whine is not normal, and sounds like a pulley or tensioner issue with one of the belt paths. Power steering have enough fluid in it?

Nah the whine is fine I know these all whine im just pointing out the sound of pressure/ air releasing escaping whistling noise when I let off the accelerator it’s most prominent. Like a vacuum leak. Thinking that has to do with why this thing feels so sluggish.

Angelo217 · Aug 31, 2024

Also will mention I get an intermittent code for a fuel tank pressure sensor which for some reason makes my ac act funny. Makes the compressor not kick on, and or it’ll be turning on and off every few minutes. Seems unrelated, just thought I should mention just incase but these are my codes
P0651 and a P0452

Fless · Aug 31, 2024

Angelo217 said:
Nah the whine is fine I know these all whine ...

Not so; a lot of them DON'T whine. Mine did a little (not as much as yours) before the power steering pump for the hydroboost was replaced. Now it doesn't.

Underpowered Possible vacuum leak

Angelo217

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Scottydoggs

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Angelo217

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Doubeleive

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