Codes 171 and 174, noticed nipple sticking out of the side of the intake

Tiny
MELISSA MEADE2
  • MEMBER
  • 2009 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
Well, I noticed a nipple sticking out of the side of the intake and it looks as if a hose should be on it but I don't know if it ever had one on it. Maybe it did maybe it didn't. I don't know what to do with it because if I turn on the truck it sucks and when I put a cap on it and it's not on tight you can hear it hissing. I do have codes 171 and 174 but I just didn't know if it's something that needs a hose and if so where's it go? If it's not important should I just try and cap it off? Not that mechanically inclined but pretty sure what I found on the internet it was the brake booster nipple.
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Sunday, December 22nd, 2019 AT 7:48 PM

4 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The codes you have indicate a lean fuel mixture. Since you have a vacuum leak, that is the most likely cause. However, I have no idea which hose you are referring to. If it goes to the power brake booster, it will be a larger hose, approximately one inch in diameter. Also, if it is for the brake booster, that means it is disconnected and you would have no power assist to the brakes. Is that the case?

If possible, could you upload a picture of what you found so I can see it? I may be able to determine what it is for. Also, let me know if there is assist for the brakes. I attached a picture of the brake booster and highlighted the vacuum supply hose to it. If you follow that hose, it should lead to a port in the intake.

Let me know.
Joe
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Sunday, December 22nd, 2019 AT 8:55 PM
Tiny
MELISSA MEADE2
  • MEMBER
Is brake assist the same thing as ABS, LOL? If it is I'm pretty sure I've seen that light on there before. I am getting the message about stable track or stability track. However the picture that you had posted above that doesn't look like what I'm looking at. The thing I'm looking at is above the fuel rail, pass. Side, above the 3 injector (from front view) right under the cover that goes on top of all of it. So I'll try putting a picture on now. Thanks for your help!
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Sunday, December 22nd, 2019 AT 9:28 PM
Tiny
MELISSA MEADE2
  • MEMBER
Joe did the pics and message go through?
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Monday, December 23rd, 2019 AT 5:23 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

I got them. I believe that is a port for the PCV system. See the attached picture to see if you see any of the hoses I highlighted.

As far as the traction control and ABS, that is most likely related to a wheel speed sensor issue. Also, if a sensor fails, you get both lights. And they are different than the booster. Have you ever pumped the brakes on the truck with the engine off? If not, try it. You will find that the pedal will get really hard to push. That is because there is no engine vacuum supplying the brake booster. The booster is nothing more than a component designed to make it easy for you to press the brake pedal and easier to actuate the brakes.

By the way, the vacuum leak you found is certainly the cause of the two lean mixture codes you indicated. The engine is drawing unmetered air through that opening and causing the codes to set.

Let me know if the picture helps.

Joe
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Monday, December 23rd, 2019 AT 10:41 PM

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